Bedbug Biology and Control
The common bed bug (Cimex lectularius) is the main species that is currently found infesting buildings and homes throughout the United States. There are a number of other species of bed bugs found around the world. These are more frequently associated with birds and bats and have been found on occasion in homes when these animals have been nesting on orwithin a structure. The tropical bed bug, Cimex hemipterus occurs throughout tropical areas of the world, thus preferring higher temperatures and humidity than Cimex lectularius. In Europe and the United States (U.S.), well-established infestations of this species are quite rare; in the Western Hemisphere, it is seldom found north of Puerto Rico and Mexico, or south of Brazil and Peru. Occasional limited populations have been found in Chile and Florida. Other species of bedbugs, including swallow bugs, bat bugs, and other bird-feeding bedbugs species occur in various temperate parts of the world. On occasion they may bite humans and are found sporadically in or around structures and homes.
Cimex hemipterus occurs primarily in more tropical areas, but has been found in temperate areas of the U.S. This is especially so when people have engaged in international travel. Bed bugs have been known by a variety of names including mahogany flat, wall louse, crimson rambler, chinch, heavy dragoon and redcoat.
Bedbug with piercing sucking mouthparts inserted into host (human) and sucking blood. Image courtesy of Center for Disease Control (CDC).
Piercing sucking mouthparts of bedbug. Image courtesy of Center for Disease Control (CDC).
Identification , Adult are reddish-brown, flattened critters that are about 3/16 inch long and up to 1/8 inch wide. After feeding on blood, bed bugs increase considerably in size and are swollen and dull red in color. Their eyes are deeply pigmented and the sides of the flattened collar-like pronotum curves somewhat around the head. The immatures (nymphs) vary considerably in size and are basically colorless (unless recently fed); the first instar nymphs are about the size of a period in this article. Bedbug eggs are white, oval and about 1 millimeter long (very difficult to see with the naked eye). Adult tropical bed bugs are approximately 1/4 inch larger than the common bed bug.
Bedbug History. It is thought that bedbugs were originally ectoparasites of bats and lived in caves, but subsequently changed hosts to include humans (cavemen) occupying in the same habitat. These pests are mentioned in medieval European texts and in classical Greek writings back to the time of Aristotle. It is believed that these bugs were originally imported into the U. S. by early Europeans. There are colonial records of the early 18th century where passengers were prohibited from bringing bedding material on ships. During the early 1900s, bedbug infestations were quite common in American homes. At that time, they were rated among the top structural pests with an estimated 1/3 of all residences infested at some point in time. However, with the discovery and use dichlorodiphenyltrichloroethane (DDT) and other insecticides in and around homes, these pests quickly disappeared. The effectiveness of these chemicals was mainly due to their long residual activity. As invariably occurs, with the overuse of pesticides, bedbugs developed resistance to DDT after a few years, but other chlorinated hydrocarbons (such DDT and lindane) and organophosphates (malathion) were used to keep these pests at a low level. The main factor why these chemicals were more effective in controlling bedbugs than modern chemicals is persistence. For example, DDT when sprayed on a bed remains active for up to 1 year. On a wall, this chemical can remains active even longer. With this residual activity, a bedbug that came to feed on a sleeping person was eliminated, and since they need to feed at one time or another, the infestation was eventually eliminated.
In many undeveloped countries, bedbugs remained and still remain important pests. In the past 10 to 15 years, bedbugs have made a huge comeback in many areas of the world including all 50 states, as well as Puerto Rico, Guam, American Samoa, Australia, Canada, parts of Europe and Africa.
In the U. S., many of major cities are presently experiencing considerable bedbug infestations. These include Los Angeles, San Diego, San Francisco and New York. Some cases have escalated to extreme levels resulting residents to label the infestations "house herpes". In California, one of the large companies that utilize bedbug dogs to detect infestations reported that they had a mere 12 searches 10 years ago. A couple of years later, the same company reported 33,000 searches. The National Pest Management Association recorded a 71% increase in bed bug calls between 2000 and 2005. Twenty five percent of the North Carolina 700 plus hotels surveyed between 2002 and 2006 required bedbug treatment. These statistics remain similar today.
Reasons for Increased Infestation. There are several possibilities why this major increase has occurred. One possible reason is a tremendous increase in worldwide travel. Nowadays, people commonly travel to and from all parts of the world. This includes many countries and areas where bed bugs are common. Also included are leisure and business travelers who commonly move between continents. In addition, countries are increasingly multicultural with residents traveling back and forth from their homelands. Of course, bed bugs are great hitchhikers and easily travel in luggage, cars, busses, cruise ships, airplanes and trains.
Another possible reason is the significant increase in illegal aliens and other temporary workers coming in from Mexico and Central America (countries where bedbug populations have remained fairly static.) They (especially temporary workers) commonly shift in and out of group residences and in low-income apartments. It is fairly common for these individuals to readily change or leave residences for new jobs or for them to return to their home country. These conditions can quickly lead to importation and movement of bedbugs.
Thrift shops, secondhand stores, swapmeets, antique stores, flea markets, and Goodwill stores are on an increase in the U.S. This is especially true with the present economic crisis. Any used item is a possible source of a new infestation. Very frequently residents will throw out furniture in attempts to rid their home or apartment of these pests. A nice sofa, chair or even new looking bed is far too attractive to some to let the trash man carry these away.
There apparently are geographic hot spots of these pests. Reportedly, there were at one point 3 apparent U.S. epicenters at poultry facilities in Texas, Arkansas, and Delaware. In these cases, workers in these farms were spreading bed bugs and unknowingly transporting them from the facilities to their residences and elsewhere.
Also changes in pest control techniques and the development of resistance to commonly used pesticides (pyrethroids) has certainly added to the reestablishment of this pest in the U.S. In the past, cockroaches were controlled by crack and crevice treatment in homes, hotel rooms, low income housing and other indoor locations. As a result, bed bugs were simultaneously controlled with these pesticides. However, during the mid-1990s there were major changes in these practices. Treatments of baseboards in motels, hotels, apartments and homes were replaced with the use of baits for ants and cockroaches. Obviously bed bugs don't feed on baits as they are blood suckers. In this absence, bedbugs were able to travel safely from the luggage or other locations--hence the beginning of the problem. It is of importance to note that once the bed bug problem developed, there were few effective pesticides available that had the residual activity needed to control these pests. Many professionals point out the dramatic rise in activity of this pest occurred approximately 10 years after applicators stopped spraying for cockroaches and instead used gel baits.
Biology.Since the common bedbug in the U.S. feeds on human blood at night (between midnight and 5:00 am), it follows that they most commonly occur around or on beds as this is where the food is, namely us. Bed bugs are attracted to CO2 produced by the victim's breath and body heat. However, they are only able to detect these host cues over short distances. This distance is about 3 feet away for CO2 and even less for heat. It is not well understood how they are capable of finding a person in a bed when initially located in a closet or other distant locations. Even though they have a very flat body (definitely not streamline) and relatively short legs, they are able to move relatively quickly; it is thought that they randomly wander in search of food. In most cases, the majority of an infestation is found on the bed. However, this is not always the case in heavy infestations. In such cases, many ultimately seek refuge at distances several yards from the host.
Bedbugs exhibit gradual metamorphosis. That is they pass through 3 stages during the life cycle, namely egg, nymph and adult. The nymphs are very similar in appearance to the adults except they are smaller but gradually increase in size with progressive molts. There are 5 nymphal instars or sizes. The eggs of these insects are tiny, white, and somewhat difficult to detect on most surfaces (individual eggs are about the size of a speck of dust or period on this page). When first deposited, they are sticky and readily adhere to surfaces thus making them difficult to remove. Under favorable conditions, each female lays 100 to 500 eggs at a rate of between 1 to 7 per day for about 10 days. She will then have to feed again to produce more eggs and is capable of producing between 5 to 25 eggs from a single blood meal. Maximum egg deposition occurs when the temperature is above 70°F and typically ceases when temperatures drop below 50°F. Eggs and their shells are found singly or in clusters and in or near crevices where bedbugs hide. At temperatures above 70°F), eggs hatch in about 10 days. At lower temperatures hatching may take as long as 28 days.
Under ideal conditions, the survival rate of bedbug eggs is approximately 97%. Even under optimum conditions, some nymphs will die prior to reaching the adult stage. This is especially true with the first instars. They are particularly vulnerable due to their small size and relatively large surface area. Newly hatched nymphs are exceptionally tiny and cannot travel great distances to locate a host. If an egg is laid too far from a host, the first instars nymph may die of dehydration before ever taking its first blood meal. However, laboratory studies have found that overall bed bug survivorship is good under favorable conditions, and more than 80 % of all eggs survive to reach adulthood. Due to the large number of eggs that female can produce under optimal conditions, bedbug populations can double every 16 days.
Without a source of food, bedbugs can enter a dormant condition and reportedly can live for 18 months while well-fed specimens typically live 6 to 9 months. However, a recent laboratory study indicates that starvation has a negative impact on bedbug survival. This modern study contradicts European studies conducted in the 1930s and 40s, when it was determined that starved bed bugs could survive periods lasting more than 1 year. This may have been true for individual bed bugs in the UK living at very low temperatures, typically below 40° F due to the presence of central heating and cold climate; modern bedbugs from homes in the United States do not live that long. On average, starved bedbugs (at any life stage) held at room temperature will die within 70 days. Most likely these bedbugs are dying of dehydration rather than starving to death. Bedbugs have no source of hydration other than their blood meal.
The unfed first instar nymph is almost translucent in color, but subsequent nymphs progressively darken in coloration. Recently fed nymphs are blood red in coloration. Bedbugs are cold blooded, like all insects. This means they take on the temperature of their surrounding environment. Correspondingly, the cooler the surrounding environment, the longer it takes them to complete their development.
Bedbugs will travel 5 to 20 feet from an established harborage to feed on a host. Nymphs and adults are gregarious (found together in groups). This grouping or “nesting” behavior is a result of 2 distinct pheromones. These are an airborne aggregation pheromone that attracts the bed bugs to the location, and an arresting pheromone that causes them to settle. Although they normally feed in the early morning hours, they occasionally feed at other times, if given the opportunity or are really "hungry". Typically, only when bedbugs are starved, will they feed during daylight hours. However, there are many well-documented cases of bed bugs feeding during daylight hours. In some cases, they have become established in movie theaters (especially older theaters with leather seats). Apparently, during the day they come out of the seats to feed when the lights are turned off. They can gain access to their host by crawling up the legs of a bed or they have even been observed crawling across and dropping from the ceiling to float down to their host.
Aggregation of Bed Bugs. Image Courtesy w.en. User Rogesoss. CC BY-SA 3.0
Mating.The mating behavior of bed bugs is at times quite competitive and strange. Males inject their sperm into the female by puncturing (penetrating) the body wall, as the female lacks a natural opening for reception of his sperm. The sperm then swim throughout the female’s body cavity eventually finding and fertilizing her eggs. Apparently, this is not limited to females. Occasionally, males are found with copulation scars where other males have penetrated their body wall. This probably happens when a male penetrates another male that is copulating with a female and subsequently injects his sperm into the mounted male. In this case, some of his sperm likely finds its way into the sperm ducts of the mounted male, which in turn is injected into the female upon ejaculation.
Bedbugs in traumatic insemination. Image courtesy of Richarde Ignell, Sweedish University of Agricultural Sciences (Wikimedia Commons)
Bites: Symptoms and Treatment
Since bed bugs are so secretive, one of the first signs of their presence (especially in an initial small infestation) frequently comes by their feeding on the occupants. The bug pierces the skin with 2 hollow feeding tubes. One of the tubes injects saliva that contains anticoagulants and anesthetics, and the other tube withdraws the blood from the host. The anticoagulant serves to prevent blood from coagulating in the tiny tube-like mouthparts, and the anesthetic serves to numb the area and prevent detection of their presence. These injected chemicals are protein based and the body reacts to their presence by producing antibodies. This frequently results in an antigen-antibody reaction, meaning that your system has become allergic to the chemicals.
The first indication of a bed bug bite usually occurs from the desire to scratch the bite area and may take minutes, hours or even weeks to occur. In most cases, the take a day or less. It is not unusual to have been bitten many times before symptoms occur. For this reason plus their secretive behavior, an initial infestation may not be detected for some time. One estimate is that it will frequently take 3 months for an initial infestation to develop to the point where it is detected by the victim. In many cases, repeated exposure to bedbug bites leads to more severe skin reactions. There are no typical skin reactions to bedbugs feeding on a person. The symptoms may vary considerably due to numerous factors. These include (but not limited to) the number of bedbugs present, duration of the infestation, previous exposure, individual physiological reaction, the species of bed bug, and the skin type of the person bitten.
There are 5 established reactions:
- no reaction (due to no or few antibodies produced);
- delayed reaction;
- delayed plus immediate reaction;
- immediate reaction only; and,
- no visible reaction.
Most human reactions to bed bug feeding consist of a raised red or flat welt which is often accompanied by very intense itching that can last for several days.
Top image: immediate reaction to bed bug feeding after 30 minutes. Bottom image: reaction after 48 hours
It is important to recognize that there are many potential causes of itching and irritation other than bedbugs. As a result, the mere present of welts, itching or other skin abnormalities are not a reliable symptom of the presence of these pests. Even dermatologists do not possess the ability to diagnose a bedbug bite. This is of significant importance considering the current frenzy and paranoia about bedbugs in the United States. It is quite probable that pest control companies receive many “false alarms” about bedbug infestations. Cosmetics, allergies, medications, drugs and environmental contaminants all can produce reactions similar to insect bites.
There are 4 general categories of conditions that can cause skin irritations:
- biting arthropods (e.g., insects or mites);
- environmental factors;
- health related conditions; and,
- personal use products.
Arthropod Bites Confused with those of Bed Bugs
Mosquitoes. The typical symptoms of bedbug bites are quite similar to that of mosquitoes but in the case of the former, the welts tends to last longer than that of the latter. Mosquito bites (at least those occurring while sleeping) are typically found on the face or other areas not covered when sleeping, while those of bedbugs can occur all over the body. Bedbug bites may not become immediately visible and can take up to 9 days or more to appear while those of mosquitoes are typically immediate.
Fleas. Typically, bedbug bites do not have a red dot in the center that is commonly characteristic of flea bites. The red dot is merely due to the fact that fleas have larger mouthparts than bedbugs. A trait shared with flea bites is a tendency towards the pattern of sequential bites often aligned in rows of 3 of more. It is thought that this may be caused by the bedbug being disturbed while feeding and relocating half an inch or so farther along the skin before resuming feeding. Alternatively, the arrangement of bites may be caused by the bedbug repeatedly searching for a blood capillary. Fleas usually bite people around the ankles, producing a small, red, hardened, and slightly raised welt. In addition fleas are most often associated with pets, although the presence of mice, rats, squirrels, skunks, or raccoons can also result in fleas infesting a home. Finally, fleas most often bite humans when their preferred hosts (pets, etc.) are removed from the premise. As long as a dog or cat is present in the house, hatching fleas will bite a dog or cat rather than humans. Obviously, timing as to when bites occur is an important consideration. If someone goes to bed and has multiple bite marks the next morning when they wake up, the likely culprit is bedbugs.
Spiders. Spider bites are a common complaint. Actuality, spiders rarely bite humans. I am 70+ years old and have never been bitten by a spider. Regardless, spider bites are characterized by 2 tiny puncture marks on the skin that correspond to their paired fangs. Spider bites almost never occur in large number on any one individual. Also, the fangs of most spiders are not large enough to bite humans.
When the brown recluse bites, it is often painless — then skin reddens, turns white, develops a red "bull's–eye," blisters, and becomes painful. Subsequently there is a degree of necrosis or rotting of the tissue. On occasion this spider does not inject venom with a bite resulting in very minimal symptoms.
Mites. Mites are very tiny arthropods which occasionally infest structures and bite people. In most cases, the infestation can be traced to birds nesting in an attic or on a window ledge. Biting mites are also found on mice or rats. When a bird or rodent dies (or the young leave the nest), hundreds of parasitic mites can migrate indoors and bite humans. Biting mites are tiny but visible to the human eye. The human itch (scabies) mite burrows into the skin and causes intense itching and irritation. Skin between the fingers, the bend of the elbow or knee, and the shoulder blades are areas most often affected by the presence of scabies. The intense itching is accompanied by a linear reddish rash.
Of course, there are 3 types of lice that infest and bite humans. Generally speaking, the only louse that may be commonly encountered in the West Coast are head lice. As indicated by their name, these lice occur on the head and cause itching. The nits (or eggs) of these pests are glued to the base of the head hairs. The eggs (see below) are similar in appearance to dandruff but remain attached to the hair. When touched, dandruff moves and lice eggs do not.
Chiggers. Chiggers also bite people and generally the biting stage (larval stage) is almost too small to be seen without magnification. Chiggers live outdoors in tall weeds and grass. They crawl onto people and move upward until they encounter a point of constriction between skin and clothing, such as around the ankles, beltline, behind the knee, or at the waistline. Chigger bites produce a hardened, red welt which begins to itch intensely within 24 to 48 hours after exposure to the mite. Consequently, victims may not associate the irritation with the fact that they were bitten while walking outdoors a day or two before. Most frequently the bites occur around the ankles or lower legs.
Household Products and Other Irritants. There are hundreds of products that can cause itching and irritation which are much more common than similar reactions caused by various arthropod bites. A few of the more common products resulting in these symptoms are phosphate detergents, cosmetics, soaps, ammonia-based cleaning agents, hair products, medications, and printing inks. Some types of clothing, especially those containing fire retardants are common sources.
Physical and Chemical Irritants. If 2 or more individuals experience the same irritation (especially in the absence of biting insects), the cause is typically environmental conditions or contaminants dispersed in the air. The most typically encountered are minute fragments of paper, fabric, or insulation. If these contact the skin, they can produce a variety of types of symptoms including a “crawling sensation” severe itching with a rash, bite like welts, and open sores. These type symptoms are commonly located in areas of the body such as arms, legs, neck, and head. Irritation as a result of exposure to paper fragments occurs in offices where large quantities of paper are processed daily. The continuous-feed paper from computers and multi-page forms generate large amounts of fragments.
Synthetic carpet, drapes, or upholstery (newly installed or in less than good condition) may shed fibers which can irritate skin. Other sources are insulation fibers released into the air by heating/cooling systems in need of repair and sound-deadening fibers embedded into drop-ceiling tiles. These are especially suspect when there have been problems with the air conditioning system or recent repair work on the ceiling.
Irritation is aggravated as a result of static electricity which attracts tiny charged fibers to skin. Static electricity may cause hair to move thus giving the feeling or thought of insects crawling over the skin.
Low humidity, electronic equipment, and fibers of nylon increase levels of static electricity. Exposure to dry air causes skin to lose moisture and can result in irritation and thus produce a condition known as “winter itch.” In addition changes in temperature tend to make skin more sensitive and cause irritation. A skin moisturizer may be or use in such situations.
Air pollution in homes as the chemical air contaminants increases, people may experience dizziness, headaches, and eye, nose, or throat irritation and in certain situations produce rashes and skin irritation similar to insect bites. In this case, these chemicals most often include ammonia-based cleaning agents, formaldehyde emitted from wall and floor coverings, tobacco, smoke, and solvents and resins contained in paints, glues, and adhesives.
Itching and skin irritation are common during pregnancy (especially during the last trimester) and may also occur in conjunction with diabetes, liver, kidney, and thyroid disease, and herpes zoster (shingles). Food allergies are another common cause of itching and irritation.
An increasing possible common cause of the sense of itching skin is associated with the use of meth, the drug of choice in many areas of the U.S. Individuals that are hooked on this drug sense itching or irritation of the skin and continually pick at their skin. I recently was contacted by a homeowner who thought she had bed bugs. Wanting to know more about this pest, I agreed to come over and check out the situation. On arrival she showed me the so-called bedbug bites. She had been to a dermatologist who suggested bedbugs were the probable cause of the same. After close inspection, no bedbugs were found. I did notice that her pupils were quite dilated and her boyfriend indicated that she continually picked at the areas of the bites-enough said.
Delusory Parasitosis-Entomophobia. Again considering the current notoriety that the American public has been experiencing in the past several years, a large number of individuals are afraid or paranoid about the possible presence of bedbugs in their homes. These 2 distinct phenomena are both based on the fear of small creepy creatures.
Entomophobia. As the name implies, entomophobia is the fear of insects. Based on a national survey, the fear of insects is ranked third in adults—closely behind the fear of public speaking and death. The fear of cockroaches is frequently ranked number one in the insect world. I would imagine that the fear of bedbugs has recently surpassed that of cockroaches.
Delusory Parasitosis. This can defined as a paranoia, or irrational fear, of small creepy non-existent creatures. Because mites are so small, in many cases this condition is diagnosed as a mite infestation. Even more commonly with the notoriety of bedbugs, the pest control operator who is called in for inspection of a possible bedbug infestation may need to deal with this phenomenon. Delusory parasitosis is more common than one might expect. Frequently, people who are inflicted with this malady are quite normal in all other phases of life and lead productive lives.
I was quite unaware of this phenomenon until one day a man in his mid 40's walked into my office and indicated that the UCLA Medical Center had referred him to me. He indicated that he and his home were infested with small 'bugs' that he could not eradicate. After a short discussion, he reached out into the air and indicated I had them in my office also. I responded that he must have brought them with him. He further stated that he had captured some and placed them on a piece of scotch tape. He related collecting each ‘critter.’ The first had bitten him on the leg and then disappeared under his skin, but he dug it out with a sewing needle. The second was on his pants cuff and bit him on the ankle. The third was found swimming around in his toothpaste. After considerable discussion, we examined each 'critter' with a microscope. Needless to say, none resembled an insect or mite. Indeed, they were small grains of sand, pieces of lint and so on. However, even after this close inspection and working with him over a several-week-period, he could not be persuaded that the attacking creatures were imaginary. The situation became so bad that he convinced his wife that she was also infested. They had arguments over who had the most. They couldn't get them out of their home, even though several exterminators were called. Because of the infestation, the home was eventually sold at a considerable loss. Eventually, partly because of the turmoil, their marriage ended in divorce.
There have been many similar situations since then. One of the most unusual occurred a few years ago when a city official from Mission Viejo (Orange County) called me and indicated that he had a whole neighborhood infested with scabies mites (see below). Scabies are parasitic mites that commonly infest humans. At the time this didn’t seem questionable because a number of the people had been to medical doctors and had been treated for this mite. These treatments didn’t seem to solve the problem, so I was brought in as a consultant. The main problem was centered on one particular resident. This woman apparently had convinced much of the neighborhood of the widespread infestation. She was using very drastic measures to try to eliminate these mites from her house and family. She would use lye to scrub down the beds on a weekly basis. On several occasions she washed her kids down with gasoline. Of course, upon hearing this, I began to realize that the whole situation was more than a little irrational. The final clincher was when she indicated that the whole problem started when she brought a potted plant back from Arizona and, while it was sitting in her bathroom, a pod grew out of it and blew these tiny critters all over the neighborhood.
Probably the most severe and possibly dangerous was a recent case where a tenant was suing his landlord for an infestation of a number of household pests. According to him, the apartment he rented was infested with cockroaches, bedbugs, housedust mites (in the attic), cats, rats, mice and even scabies mites. According to him, he became so paranoid about the whole situation he stopped taking his HIV medication and subsequently developed AIDs. He called in a pest control company that treated mainly for cockroaches but could not find any bedbugs, rat or mice. He indicated that the company told him that the attic was full of housedust mites that were biting him and causing a severe rash. He went to an emergency center that routinely prescribes 5% permethrin cream for scabies mites. This material is quite effective and it typically takes one treatment for successfully eradication even though there is enough in one tube for 3 treatments. Needless to say he treated himself on 3 separate occasions with the material. However since the rash remained, he went to another doctor (this time through his medical insurance) and was prescribe an additional tube of the material. Needless to say he also went to his AIDs doctor for another prescription. In the end he received 3 separate prescriptions from each of the 3 doctors and treated himself 9 times over a few month periods.
If that wasn’t enough, he decided to treat for cockroaches and bedbugs (even though 2 separate pest control companies were brought in for the same purpose with the second finding no roaches or bedbugs). He initially tried several different chemicals that he sprayed with apparently no acceptable results. He then tried using aerosol bombs lighting several per room on 3 occasions. He was lucky he didn’t blow the places up since with overuse combustion is possible, especially with the older products that were available at that time. Finally on the initial visit to the emergency room, the doctor checked for head lice but didn’t find any. Of course that wasn’t enough for the tenant so he routinely treated for head lice with an over the counter pesticide cream. The amazing thing is, besides that he didn’t kill himself with all the pesticides, he received a $20,000 settlement in the lawsuit.
A colleague from NCSU, Mike Waldvogel, reports similar experiences. He states he has received a variety of imaginary critters in vacuum cleaner bags, pillows cases, panty hose, skin samples, glue boards (like the one you use for catching mice) and (the one he described as the ultimate) a bottle (formerly a pint gin bottle) that was labeled "after douching." Needless to say that one wasn’t opened! Neither were the vacuum cleaner bags, as they usually contain pesticide-laden dust from over treated carpets for these so called pests.
All of these cases have had several symptoms in common. The 'critters' typically fly through the air, crawl on the skin, frequently appear and disappear in the skin, make clicking noises and can be found in soap and toothpaste. Generally, inflicted individuals have gone to several medical doctors to no avail and can almost never be persuaded that the pests are imaginary.
Treatment of Bites. Systemic corticosteroids for treating the itching and burning often associated with bedbug bites in many cases are less than effective. Antihistamines can reduce itching in some cases, but typically do not affect the appearance and duration of the lesions. Topical corticosteroids, such as hydrocortisone, reportedly are effective in reducing lesions and decreasing the associated itching.
Application of heat (blow-dryer, hot washcloth, hot water) can be effective in relieving itching and inflammation for several hours. The water temperature should be about 50 °C (120 °F), or this procedure may aggravate the symptoms. To avoid scalding the skin, this treatment should only be self-administered. Conventional insect repellents, like those containing DEET used to deter ticks and mosquitoes, do not appear to be effective against bedbugs. Attempting to avoid being bitten by applying insect repellent at bedtime is not recommended. Sleeping with the lights on is not likely to deter hungry bedbugs either.
Means of Infestations. Multi-unit buildings ((e.g. apartment buildings) can be very difficult to eliminate bed bugs. These pests infest a new residence by traveling between multi-unit housing such as condominiums, dormitories, and apartment buildings. This spread between adjacent home sites and nearby units is not only dependent, in part, upon the degree of infestation at the source, but also upon the building material used to partition units and the material used to seal connecting pipes, vents, wires, etc. Further potential to spread is also directly related to the manner in which infested items are disposed of—such as whether or not contaminated furniture is dragged through common areas while being removed.
Infestations can result from bringing infested furniture or contaminated, used clothing into a home. One of the worst things a person can do is pick up and use furniture that has been discarded. It is not uncommon for someone to discard a perfectly good piece of furniture that has a bedbug infestation. Furniture does not necessarily have to have been previously owned or discarded—as even brand new furniture can be exposed to bedbugs during storage or in delivery vehicles.
A big problem is delivery trucks. A good example would be someone buys a new bed. It is delivered by a delivery system that in turn picks up the old bed in the same truck. What are the chances of that old bed having bedbugs or at least some of the hundreds of mattresses that truck has picked up having bed bugs? Sooner or later that truck is going to be infested with bedbugs. It only takes one impregnated female which is capable of depositing 200 or more eggs to start a new infestation. Back in the 40’s it was not uncommon to treat such vehicle for bedbugs. I am not sure the industry is at that point yet.
In locations that are severely infested, bed bugs may crawl onto a person's clothes and hitched-hiked from location to location. It is also not uncommon for these pests to occur in clothing that is typically not frequently used and subsequently spread when such items are stored publicly with other apparel (as in locker rooms and on coat racks). Otherwise, these pests are not typically carried from location to location by individuals on the clothing they are currently wearing. General machine washing and drying on high heat will kill all stages of these pests.
The size of a bedbug infestation can range from a few to several thousands. A single female bedbug that is introduced into a structure can quickly produce geometrically resulting in a significant infestation. In any case, bedbugs have a tremendous reproductive capacity and it is not unusual to encounter thousands of these pests a single mattress. Sometimes people are not aware of the insects and do not initially notice the bites. The visible bed bug infestation rarely if ever represent the overall infestation, as there may be large numbers elsewhere in a home and the sighting of one bed bug typically means that there may be many more in hiding. However, the insects do have a tendency to stay close to their hosts (on the bed), consequently the name 'bed bugs'.
Steps to Minimize the Chances of Bringing Bed bugs into a Structure. The initial step is to be aware of where bedbug infestation may occur. Commonly infested areas included locations with a high turnover of individuals spending the night—multiunit residences, hostels, hotels near airports and amusement parks, and resorts are typically most at risk. There are many more that could be listed such as barracks, buses, cabins, churches, community centers, cruise ships, dormitories, dressing rooms, health clubs, homes, hospitals, jets, Laundromats, motels, motor homes, moving vans, nursing homes, office buildings, resorts, restaurants, schools, subways, theaters, trains and used furniture outlets. Bed bugs don’t prefer locations based on sanitation or people’s hygiene. The critical component for their survival is food, or put more simply our blood.
Most stay near where individuals sleep with the most common locations being beds, but certain include couches or armchairs (if that’s where you snooze)—even cribs and playpens. Their flat body allows these pests to hide in cracks and crevices and anywhere in a room and in furniture joints. Hiding sites include mattress seams, bed frames, nearby furniture, or baseboards. Clutter offers more places to hide and makes it harder to get rid of them. Bedbugs can be found alone but more often congregate in groups. They’re not social insects and don’t build nests
Traveling greatly increases the chances of bringing bedbugs home. Therefore wise travelers should be aware how to avoid this possibility. The first set of moving into a hotel is to inspect before settling into any room. It is worthwhile to pack a flashlight (even the keychain LED model) and gloves to help in your inspection. The inspection should focus on the bed, starting with the headboard. After checking the headboard, search for blood spots and feces on the pillow and sheets. It is worthwhile to note that in hotel rooms that are commonly used, the bedbugs may be in highest number behind the headboard, as constant changing of the sheets may drive most of them off the bed. Next, pull back the sheets and check the piping of the mattress and box spring. Finally, look in and under the drawer of the bedside table.
If you find evidence, but no live bedbugs, the evidence may be old and doesn’t mean that the hotel has an infestation. These pests are a nightmare for the hotel and motel industry. If you run to a competitor (who’s just as likely to have bed bugs), it makes it less likely that the industry will become more open about this issue. Communication is key. Ideally hotels and motels would pride themselves on their bed bug programs and show customers how to inspect to keep all parties bedbug free.
It is best not to unpack clothing into drawers and place closed luggage on a luggage rack that is pulled away from the wall. Do not place luggage on a bed and it should be kept closed especially at night. It follows to not leave clothes around the room at night. A good place to keep a suitcase is in a bathtub. The chances of bedbugs finding your luggage in that location is very slim.
Clothes should be laundered prior to or as soon as they are brought back into your house. If you found these pests after moving into a hotel room, it wouldn’t hurt to ask the hotel to pay for laundering and for steam-cleaning the luggage. The hotel may refuse, but it’s worth asking but many will do so. Regardless, once home you should unpack on a floor that will allow you to see bed bugs—stay off carpets! Unpack directly into plastic bags for taking clothes to the laundry. Suitcases should be carefully inspected and vacuumed.
Bedbugs and Disease. Bed bugs appear to possess all of the necessary criteria for transmitting diseases, but there have been no known cases of these pests vectoring or transmitting any disease. Bed bugs have been found naturally infected with at least 30 human pathogens but have never been proven to transmit any of them biologically or mechanically. There are some indications that bed bugs may be a vector for hepatitis B and in endemic areas, for American trypanosomiasis (Chagas disease). Of note, reports have indicated the risk of insect transmission of HIV, if any, is extremely low and likely nonexistent. Therefore from a disease transmission standpoint, bedbugs are considered less dangerous than some more common insects such as the flea.
Inspection-Detection. Inspecting for Bed bugs. Controlled Study-Dogs. The bedbug is difficult to visually detect because of its cryptic nature. Detector dogs are useful for locating these pests because of their tremendous sense of small. Dog’s sense of smell is 250 times as effective as that of humans. Dogs can be trained to detect these pests, as few as one adult male or female and their eggs by using a food and verbal reward system. Their efficacy was tested with bedbugs and viable bedbug eggs placed in vented polyvinyl chloride containers. Dogs can discriminate these pests from carpenter ants, German cockroaches and drywood termites with a 97.5% positive indication rate and 0% false positives (incorrect indication of bed bugs when not present). In addition they discriminate live bed bugs and viable bedbug eggs from dead bed bugs, cast skins, and feces, with a 95% positive indication rate and a 3% false positive rate on bedbug the latter. In a controlled experiment in hotel rooms, they reportedly were 98% accurate in locating live bedbugs.
Inspecting for a bed bug infestation can be quite simple to quite time consuming depending of course of the extent of the infestation. Customer cooperation is a valuable tool in this process. Client involvement is important when battling bed bugs. Especially important are instructions pertaining to preparation before treatment. Providing access for inspection and treatment is essential and in some cases, infested items will need to be discarded. Clutter is a particular problem in homes and apartments, obstructing treatment and affording additional places for bed bugs to hide. In uncluttered situations, industry surveys indicate that 2 or 3 treatments are normally needed to get infestations under control, whereas in cluttered situations 4 or more treatments are often necessary. Items must be removed from floors, and furnishings moved away from walls.
Bedding and clothing should be bagged and laundered, although this may not be totally possible and judgment should be used as to what is most vulnerable. Reportedly a standard wash cycle using hot water effectively kills all life stages, including eggs and clothing placed into clothes dryer at high heat (80°C) for as little as 5 minutes achieves the same result. Reportedly clothing placed in a cold water wash, about 1/3 of bedbug adults survived as did most eggs. It is generally considered poor taste to take bed bug-infested items to professional drycleaners to avoid the risk of the establishment being infested.
An Engorged Female Bed Bug in a Screw Hole of a Wooden Bed Frame. Image Courtesy CDC,
Bedbugs are relatively small insects with a flat body. As a result they have a relatively large area where water can evaporate from their body and subsequently are quite susceptible to dehydration. It follows that they hide in cracks and crevices and are frequently found in congregations to minimize this potentially deadly possibility. Cracks or crevices the width of a credit card or smaller is ideal. Keeping in mind that the first instars nymphs are no larger than a speck of dust. The size of these hiding locations (cracks or crevices) can be quite small.
Use of a crevice tool to reach into small spaces as well as the use of a magnifying glass and/or flashlight can assist in the successful detection of bedbugs and their symptoms. A crevice tool, however, can be improvised but—very importantly—should consist of a non-conductive material such as plastic or wood if it is to be used to probe walls, baseboards, and/or electronics, etc. (to prevent electric shock).
Bedbugs travel easily and quickly along pipes and boards, but typically do not travel more than 100 feet from their host (us). As a result the most common place to find them is the bed. Bedbugs often hide within seams, tufts and crevices of the mattress, box spring, frame and headboard.
A successful inspection requires dismantling the bed, and standing the components on edge so that upper and lower surfaces can be examined. As previously discussed, signs of an infestation include bugs themselves, light-brown cast nymphal skins and less commonly blood spot from crushed bedbugs. Bed bugs frequently defecate where they feed or rest leaving dark spots of dried bedbug excrement. Obviously their feces contain a high component of dried blood. If no sure a moist rage applied to this material will reveal the redness of the blood. The feces are frequently found along mattress seams or wherever the bugs have resided. Box springs are a common harborage, especially underneath where the fabric is stapled to the wooden frame. Frequently the underlying gauze dust cover must be removed to gain access for inspection and possible treatment. Cracks and crevices of bed frames should be examined, especially if the frame is wood. (Bed bugs have an affinity for wood and fabric more so than metal or plastic). Headboards that are attached to walls should also be removed and inspected. In hotels and motels, the area behind the headboard is often the first place that the bugs become established. Bedbugs also hide among items close to bed, especially those stored under beds.
As infestations increase in size, a small percentage of the bedbugs move to locations always from the bed. The larger the infestation becomes, the higher the overall percentage and increased spread through the structure becomes. Upholstered chairs and sofas should be examined above and beneath, especially seams, tufts, skirts and crevices. Sofas can be major bed bug hotspots, especially when used for sleeping. Like beds, they can be difficult to treat and may need to be discarded. Nightstands and dressers should be emptied and examined inside and out, then tipped over to inspect the woodwork underneath. Oftentimes the bugs will be hiding in cracks, corners, and recesses. Other common places to find bedbugs include: along and under the edge of wall-to-wall carpeting (especially behind beds and furniture); cracks in wood molding; ceiling-wall junctures; behind wall-mounted picture frames, mirrors, switch plates and outlets; under loose wallpaper; amongst clothing and clutter stored in closets; and inside clocks, phones, televisions and smoke detectors. Even though bedbugs possess scent glands and produce a sweet musty, such odor is not a key to detect their hiding places (possibly with the exception of dogs).
Bedbugs tend to congregate in certain areas, but it is common to find a single bug or some eggs scattered here and there. Persistence and a bright flashlight are requisites for success. A thorough inspection and treatment may take up to several hours. Some companies are beginning to use dogs for detecting hard-to-find infestations. When properly trained, the dogs can be very effective. However at this time, very few companies are using them due to the expense of training and maintaining such animals.
The presence of bedbug feces will be one of the primary signs of an infestation. Bed bug droppings are black or nearly black in color and often will often appear as dots or specks that are similar in appearance to a dried drop of ink. The feces is digested blood. These small pitch-black droppings will vary in size (ranging from tiny and difficult to see up to the size of the bugs themselves), but can be distinguished from other dark debris in that it will readily smear (or bleed red) if exposed to water. Rubbing the black fecal spots with a wet wipe will work well. The deposits may also be found, not as circular dots, but as dark pinstripe-like markings that are small and streaked in appearance. Feces will occur anywhere bed bugs may be harbored but might also be found or along routes back to a nesting location --- i.e. which might be on the pillowcase or, mattress, sheets, bed frame, curtains, in baseboards, in crevices, in seams, under the couch, under chairs, etc. Successful detection of bedbug feces might require a considerable degree of extra vigilance and careful searching in light cases of infestation.
The presence of cast skins is another indication that bedbugs are present but well hidden. Bed bugs will shed their skins throughout multiple instars of their lives and the discarded outer-shells (which will vary in size according to the instart and can be extremely small) might be found near any of the various locations where they have harbored. The sloughed off skins appear as clear, empty exoskeletons of the bugs themselves. And the actual living bugs may or may not be nearby the discarded shells.
The presence of bedbugs may also be confirmed through direct discovery and identification of the insects collected or by a pattern of bites. Though bites can occur singularly, they often follow a distinctive linear pattern marking the paths of blood vessels running close to the surface of the skin. It should also be noted that confirmed bedbugs may vary slightly (or even markedly) in appearance, color, or shape and depending on the insect's current size, stage in life, and whether or not they have recently fed.
A technique for catching bed bugs in the act is to have a light source quickly accessible from your bed and to turn it on at about an hour before dawn, which is usually the time when bedbugs are most active. A flashlight is recommended instead of room lights, as the act of getting out of bed will cause any bedbugs present to scatter before you can catch them. Bed bugs are fairly fast in their movements, about equal to the speed of ants. They may be slowed down if they have engorged on their food source. When the bedroom light is switched on, it may temporarily startle them allowing time for you to get a dust pan and brush kept next to the bed and sweep the bugs into the pan then immediately sweep them into a cup or mug full of water where the bugs drown quickly.
Correct diagnosis of a bedbug problem is important. As indicated older established infestations are fairly easy to detect; but in the early stages, they can be much more subtle. As people become more aware of this pest, all manner of welts and itches may be attributed to bed bugs though they are often caused by other factors. One reason bedbug elimination is so challenging is that they can hide almost anywhere. Most aggregations reside near a sleeping host, but as infestations persist, others are found in various locations within several meters of the bed. Based on an industry survey, the most common areas for finding bed bugs were beds (mentioned by 85% of respondents), bedding (mentioned by 52%), baseboards/carpet edges (37%), furniture such as nightstands and dressers (26%), couches and chairs (25%), walls and ceilings (14%), and clothing (6%). Bedbug counts in 13 infested apartments in Ohio revealed a similar distribution pattern, with 70% of all bugs associated with beds. When inspecting multi-occupancy dwellings such as hotels and apartments, most survey respondents (91%) said they routinely recommend inspecting surrounding units adjacent to infested units. This seems prudent considering other industry surveys have found adjoining units to be infested much of the time.
The following is a reasonable approach for inspecting a facility for bedbugs.
- Furniture, particularly bedroom furniture must be inspected carefully. Bed bugs may crawl 10-20 feet; so don't limit search only to the bed.
- When feasible beds should be dismantled for easier inspection and possible treatment. Inspect the mattress and box spring thoroughly. Be sure to check the holes or slots where sections such as the sides, head and foot boards attach.
- Check under and behind other pieces of furniture, such as chairs, couches, dressers, nightstands, etc.
- Pull out dressers drawers, inspect them carefully and check the interior of the dresser before reinserting the drawers.
- Check the undersides of lamps, clocks, radio, phones and other objects that might be on nightstands.
- Pull back the dust covers on the undersides of chairs and couches and check particularly around the legs and frame.
- Remove and inspect objects, such as pictures, mirrors, curtains, etc., that are hung or mounted on walls.
- Check obvious cracks and crevices along baseboards.
- Remove the covers on electrical outlets and switches and inspect the boxes for signs of bedbugs.
- Inspect torn or loose wallpaper and decorative borders.
- Check all clothing and other items stored in areas where bed bugs have been found.
- If you have traveled in the last few months, inspect your luggage as well as the entire closet/storage area (and its contents) where you store your luggage.
Bed Bug Monitoring Devices. In the past few years there have been a number of devices designed to monitor low levels of bedbug infestations. They vary tremendously in price ranging from approximately $1 to $1,000. There appears to be very little scientific testing comparing (at least based on nonbiased organizations) the relative effectiveness of each. Some are passive, meaning there are no attractants drawing the bedbugs to the trap and other utilized either or a combination of heat, CO2, and attractants (pheromones) to draw the insects to the trap. The projected purpose of these traps is to monitor the presence of possible bed bug infestations in a structure. However, since many insect traps in general catch a moderate number of insects that are attracted to them, it logically follows their use will not significantly reduced or eliminate an existing infestation. The relative effectiveness of the various devices has not been compared.
Bedbug Mattress Covers. A number of companies have developed special covers that can be used to encase all size of mattresses (and pillows) for bedbug control. These can serve 2 functions. If a bed is suspected of harboring bedbugs, they can be used to encase a mattress, thus effectively preventing a potential infestation from escaping and biting. More importantly the covers when properly fitted eliminate the seams, crevices and other preferred bedbug hiding locations on the mattress. This makes it much easier to find and control an infestation on a bed.
An important issue in managing bedbugs is what to do with the bed. Beds offer perfect harborage in the immediate vicinity of the host. While frames and headboards are rather easy to service, mattresses and box springs are not and are often main reservoirs of infestation. If there are holes and tears in the fabric, bugs and eggs may be inside as well as outside. This is especially true of box springs, which have plenty of places for bedbugs to enter and hide. Some companies insist that all infested beds be discarded or fumigated, whereas others advise against getting rid of beds, rationalizing that a new one will also become infested if the infestation has not yet been eliminated. Such decisions are usually based on the condition of the bed, severity of infestation, and nature of the client. Hotels, for example, may want to discard anything that is potentially infested whereas renters on a budget may not.
A majority of U.S. pest control firms (59%) indicate they routinely recommend that infested beds be discarded, whereas 52% said they routinely utilize bed encasements. Encasing both the mattress and box spring denies bedbugs access to inner, hard-to-reach areas and entombs any bugs already inside. A tight-fitting smooth outer cover also makes it easier to detect and destroy any bedbugs reappearing on subsequent inspections.
Heat. One main battle for survival insects have in general and especially small insects is the loss of water or desiccation. A small flat insect such as a bedbug has a relatively large body surface area (where water can evaporate from) compared to their total volume for storing water. Their eggs and early instar nymphs are especially vulnerable to desiccation and therefore high heat. Since at least the early 1900s, bedbugs have been controlled by heating infested rooms or whole buildings to temperatures at least 113F, the thermal death point for the common bedbugs. For heat treatment to be effective, it is critical that high temperature and low relative humidity be attained for a minimum length of time (generally several hours). A more comprehensive way of using heat to control bed bugs was adapted from methods developed long ago to de-infest granaries and flour mills.
In the early 1900s, investigators determined that it was possible to destroy bed bugs in buildings ranging in size from a two-story house to a 350-room dormitory on a college campus. Steam boilers and furnaces were used to elevate the temperature in bed bug infested rooms to between 110˚F and 130˚F over a period ranging from several hours to a few days — a process known as “superheating.” In the first edition of the “Handbook of Pest Control,” Arnold Mallis also mentioned using superheating to successfully de-bug an animal rearing laboratory. He reported that after 8 hours of heating, “the mortality was so terrific, that a carpet of bedbugs covered the floor, and a slight draft through the room piled up windrows of the bugs against several objects on the floor.” Efforts to control bedbugs with heat diminished in the 1940s, due to the ease, economy and effectiveness of DDT. Interest was rekindled in the late-1980s when Drs. Walter Ebeling and Charles Forbes demonstrated the utility of structural heating against drywood termites, wood-boring beetles and cockroaches.
This type of treatment has several pros and cons. Heat treatment provides no residual effect, and bedbugs can re-occupy any treated site immediately after temperatures return to suitable levels. There is the possibility of damages to structures and their contents. Of greatest concern is the possibility of fire. However the latter is becoming of less concern with the development of a numbers of commercially available safe heat generators. It should be mentioned that initial cost of these heat generators can be quite costly but on the positive side the utilization of heat for bed bug control can be cost effective and if properly applied can result in total control of these pests including their eggs. The latter is significant since few of the currently available pesticides will kill their eggs.
Heat can be an extremely valuable tool in removing (killing) all stages of this pest from clothing, sheets, blankets and other linen. Laundering infested items in hot water with detergent, followed by at least 20 minutes in typical clothes dryer on low heat should kill all life stages of bedbugs. A number of pest control companies have now incorporated heat as part of their pest management scheme for controlling these pests. On a commercial basis, the use of heat is especially attractive for smaller structures or units such as college dorms, hotel rooms and the like.
Customers do not want to be burdened with the invasiveness of a chemical treatment. Homeowners frequently have to spend hours cleaning out a room before a remediation treatment can take place, throwing away belongings and taking time to preserve precious items somewhere safe from the treatment. Heat remediation offers a form of treatment where owners only need to remove the items that will be adversely affected by the heat.
Reportedly there is typically no follow up treatment needed for a heat remediation. Depending on the extent of the infestation with pesticides, several follow up treatments may be needed to ensure that all the hidden bugs and eggs have been destroyed. Another big selling point is the turn-around time, and this is especially true for commercial clients such as hotels. Heat remediation only requires that the premises be vacated during the treatment and for a long enough time for the heat to disperse, generally 24 hours. For a hotel operator, this is a selling point. They can turn the room around in 24 hours and not lose nearly the amount of revenue as they would if they had to undergo a chemical treatment. The most important difference is the effectiveness of heat remediation. Heat remediation kills all the bugs and eggs in a room typically on first treatment. It is even effective through the walls into the surrounding wall voids of a room. Another plus, one that sells especially well these days, is that heat remediation is Green. Once the treatment is over, the heat dissipates. With chemical treatments, there are all manner of chemical residues left behind after the treatment. Not to mention the industrial processes required to create the chemicals in the first place.
Generally there are 2 types of heat remediation devices, namely propane powered and electrical powered. Propane powered equipment involves bulky ductwork, leaves residual fumes, and presents a potential fire hazard that can give pause to not only the customer, but also PCO’s. Electrical devices on the other hand have traditionally been overly large and cumbersome, requiring more than several people to assist in set-up and operation. One of the keys to operating these devices is the ability to slowly warm up a treated room. If a room is heated too rapidly, some of the bedbug may escape or be driven from the room.
It follows that any heating system should have the ability to monitor the rate of heating up of a location.
Cold. The use of cold for bedbug control is generally not that effective and as cost effective as the use of heat. Bedbugs can tolerate 5 degrees Fahrenheit for short periods and, if acclimated, they can survive at or below freezing continuously for several days. Cold treatments of rooms or buildings to control bedbugs have not been well studied or often employed, but freezing furniture or other items within containers or chambers, e.g., below 0oF (-19oC) for at least 4 days, may be a practical alternative for limited infestations or to augment other control measures.
Steam. Steam treatments have been used effectively by some PMPs to quickly eliminate live bugs and their eggs from the seams of mattresses and other cloth items. However, this technique requires training, practice and care. Manufacturers’ instructions must be followed concerning the steam generating devices’ operation, maintenance and safety precautions. The steam emission tip must usually be about 2.5 to 3.8 cm from the surface being steamed. If the tip is too far away, the steam may not be hot enough to kill all the bedbugs and eggs that it contacts. If the tip is too close, excess moisture may be injected into the treated material, which may lead to other problems like facilitating dust mite population survival and increase and growth of surface molds.
Monitors. Sticky traps are a simple way to monitor many crawling insects, and have been used to augment other techniques for control of spiders and cockroaches. Although bedbugs will often get caught on such monitors, many recent reports from PMPs in North America have indicated that they are not very effective at detecting small to moderate populations of bedbugs, even when infestation signs are obvious, bugs are easily observed, and people are being bitten routinely.
Pesticide Applications-Residual Applications. Currently, non-chemical products and techniques are incapable of efficiently or quickly controlling or eliminating extensive or well-established bedbug populations. Precise placement of a suitably labeled, registered and formulated residual chemical insecticide is still the most commonly used bedbug control. Effective control consists of applying interior sprays or dusts to surfaces that the bedbugs contact and to cracks and crevices where they rest and hide. When using residual insecticides, care should be taken to select the least-toxic active ingredients and formulations and following an IPM approach. Microencapsulated and dust formulations have a longer residual effect than others. Synergized pyrethrins are often lethal to bed bugs, and some may cause a flushing effect, allowing faster analysis of the infested area. If the product label permits, addition of pyrethrins at 0.1-0.2% to organophosphate, or carbamate (where these active ingredients are legal and labeled for this use), or other microencapsulated insecticide formulations may increase efficacy by irritating the bugs, exciting them, and causing them to leave their hiding places, thus increasing their potential exposure to the freshly deposited insecticide.
Inorganic Materials. Silica gel, boric acid, and diatomaceous earth will provide long-term control, provided they are used in an environment with low humidity. These inorganic materials have very low repellency, a long residual life, and can provide good control if thoroughly applied to cracks and crevices. However, they are typically white in color and may leave the surface of items with an undesirable film unless they are carefully applied.
Inset Growth Regulators. This group of insecticides mimics the activity of the naturally occurring insect hormones that control the process of molting and growth. There are 3 hormones that control these processes but because of difficulties in molecular complexity, isolating and producing 2 of these (namely ecdysone and the brain hormone) the insecticide mimics are based on the juvenile hormone. They are referred to as mimics since they are not the exact molecular structure of juvenile hormones but similar enough in structure that they have the same effect on insects. Juvenile hormone regulates what an insect will molt into. If there is a high level in the blood at the time of molting, the insect will stay in a juvenile stage (e.g. larva molts into larval stage, nymph to nymph). If there is a low level of this hormone, the insect will advance in stage (e.g. larva into pupa, nymph into adult). It follows that when abnormal amounts of the mimics (higher than what occurs in nature) are applied to these insects, abnormal molts occur making the insect unable to function normally and typically killing them. Since applications of these chemicals are much higher than those occurring in nature, the results are the same. Applications of Insect Growth Regulators typically prevent eggs from hatching and result in abnormally nonfunctioning nymphs. There are some advantages and to using these materials. They reportedly have a relatively long residual activity (up to 7 months indoors) and due to their mode of action and low concentration in sprays, they are one of the “safer” pesticides. One drawback is that they have little if any effect on the adults stage. As a result it is strongly suggested that they be used in conjunction with an adulticide.
Some of these Insect Growth Regulators are currently being used with an adulticides for bedbug control. Suggested applications include directly to areas such as crevices, baseboards, floors, ceilings, or walls. Make spot treatments to areas such as storage areas, closets, around water pipes, doors, windows, and behind and under appliances/equipment, furniture and beds. According to one of the representatives from one of the manufacturers, the IGRs are relatively ineffective for bedbug control.
Best Yet Cedar Oil. Recently there has been a tremendous amount of advertisements touting cedar oil as a “green” source for controlling bed bugs. Although not generally adopted by the pest control industry due to the vast amount of advertisement, it is apparently finding considerable use by the general public. Cedar chests have been used for hundreds of year as a means of protecting its contents (e.g. wool, etc. from fabric feeding insects). The effectiveness of this is due to cedar oil which is documented to have repellency to these insects. . The following is the results of a study performed by Changlu Wang at Rutgers University (funded by bed central). This study was intended to test the effect of Best Yet cedar oil when sprayed directly on bedbugs and their eggs, as well as its residual effect when bedbugs were forced to remain confined to a treated surface for a 14-day period.
The results demonstrated that when bedbugs and their eggs were sprayed directly with Best Yet cedar oil there was 100% mortality of bedbugs within 1 minute and within 17 days none of the eggs hatched. When untreated bugs were moved to a treated surface that was allowed to dry for 24 hours prior to exposure, the bugs started to show mortality 3 days after exposure and after 14 days about 67% of the bugs had died, compared to less than 20% mortality in the untreated control. It is significant to consider that the residual test was a forced exposure which may not mimic the actual field behavior of the bugs (i.e. most researchers believe that most bedbugs, when in a home, will not remain on a surface treated with a repellent chemical for long periods of time). In addition, it is also worth noting that the product did show some repellent properties with bed bugs, which may further reduce the likelihood of bed bugs remaining on treated surfaces long enough to achieve mortality in field settings.
These promising results stimulated Dr. Wang to look further into what part of Best Yet is causing the insect mortality. According to the label on Best Yet, the product contains 10% cedar oil and 90% latex. When 10% cedar oil was applied to bed bugs, it did not cause any mortality of bed bugs. A conversation with the manufacturers of Best Yet indicated that they were aware that “over-the-counter” cedar oil would not cause bed bug mortality and that they manufacture their cedar oil in a way that gives it insecticidal properties. Also, latex has a physical property consistent with that of household paint but Best Yet is a clear, not nearly as viscous as paint. When an applicable form of latex was applied to bedbugs the bugs did not demonstrate any mortality, but what “latex” is can be interpreted many different ways.
Looking further into the latex situation, the label on Best Yet states that 90% of the product consists of latex but the MSDS sheet states that the product consists of silicon. Some professionals do consider silicon a type of latex but either way, more research needs to be done to determine what gives Best Yet its insecticidal properties.
Botanical Insecticides. Insecticides containing natural pyrethrins will repel insects and can “knock down” bed bugs for a period of time, but natural pyrethrins quickly deteriorate and does not provide the necessary residual action of some other materials. Finishes on furniture and other wood items may be damaged from the petroleum carriers contained in aerosol pyrethrins. In addition these chemicals tend to be relatively expensive. Fogging is generally considered ineffective for bedbug control due to the inability of content to reach deeper seated infestations,
Dessicants. Inorganic materials such as silica gel, boric acid, and diatomaceous earth will provide long-term control, provided they are used in an environment with low humidity. These inorganic materials have very low repellency, a long residual life, and can provide good degree of control, if thoroughly applied to cracks and crevices. However, they are typically white in color and may leave the surface of items with an undesirable film, unless they are carefully applied. These materials work primarily as desiccants. As previously mentioned, one of the main battles insect have is loss of water. Being small they have a relatively large surface area where water can evaporate from and a comparative small body volume to store the same. In order to minimize water evaporation, the outside of their body is coated with a thin waxy layer. Of course the various desiccants work primarily by abrading this wax form their exoskeleton. It would seem like these material would be effective in controlling bed bugs due to their extremely small size (as far as insect go) and their flat body (thus decreasing their body volume).
Synthetic Pyrethroids. Some synthetic pyrethroids can provide good control, if they are carefully and thoroughly applied to suspected bed bug harborages. Many are relatively long-lived residuals and will not damage materials that are not harmed by water. Consideration should be given to the fact that people typically spend in excess of 8 hours per day in the bedroom. If the insecticides are properly applied, there should be little risk of exposure. Recent studies have demonstrated that some populations of bedbugs are exhibiting resistance/tolerance to several of the more commonly used synthetic pyrethroid insecticides. Considering the current resistance to these products, when available, it is advisable to consult experts as to the degree of current resistance to a pyrethroid based product.
Fumigation. Fumigation of furniture, clothing, or other personal items can kill all bedbug stages. However, such treatments will not prevent re-infestation immediately after the fumigant dissipates. Fumigation of an entire building would be equally effective but, again, would not prevent re-infestation, and would seldom be necessary, practical, or affordable. Many companies recommend tent fumigation with Vikane.
Contamination of SoiI and Movement to Water Table. Movement of pesticides in the soil and contamination of underlying water tables is always a consideration with the use of pesticides, especially in a pest management program. None of the above discussed pesticide presents a problem from that aspect. However pryrethroids (Suspend SC, Bedlam, Onslaught, Demand SC, Phantom) are all toxic to fish and aquatic invertebrate and should not be applied to water (streams, lakes) or near water if this possibility exists. Considering the fact that as used for bedbug control (e.g. indoor applications), this is not considered a potential problem. Fumigation with Vikane is also not also considered a problem from this aspect as the chemical quickly breaks down to non toxic materials and is confined to inside a structure. The inorganics discussed above are natural components of soil and again are confined to inside a structure when use for bedbug control. Finally pyrethrin has a very short residual and presents no problem as far as this aspect is concerned.
Ultra Low Volume (ULV), Aerosols, and Foggers. Insecticides currently labeled for ULV, aerosols and foggers have little or no residual effects on bed bugs. Most will seldom penetrate cryptic bed bug harborages. If directly injected into harborages, these products may stimulate some bedbugs to become active and move out into the open, allowing them to be more readily seen. Otherwise, bed bugs are seldom killed, even by prolonged or repeated exposure to such products as those currently EPA-labeled in the bedbug, bat bug and related species of the family Cimicidae.
True/False Accreditation Questions,
1. It is thought that bed bugs were originally ectoparasites of bats in caves, but then changed hosts to include humans (cavemen) once they were found in the same habitat.
2. During the early 1900s, bed bugs infestations were quite common in American homes. They were rated among the top structural pests at that time with an estimated 1/3 of all residences having infestations at one time or another.
3. Based on modern studies, on average starved bed bugs (at any life stage) held at room temperature will die within 100 days.
4.The mere presence of welts, itching or other skin abnormalities is not a reliable symptom of the presence of bed bugs.
5. With fairly large percentage of people, the bite of bed bugs cannot be felt until minutes, hours or even later with the first indication of a bite usually occurring from the desire to scratch the area.
6. The aggregation behavior of bedbugs is a result of 2 distinct pheromones, namely an air-born aggregation pheromone that attracts the bed bugs to the location and an arresting pheromone that causes them to settle.
7. Although bedbugs normally venture out to feed in the early morning hours, they occasionally feed at other times if given the opportunity and have been observed active during all periods of the day. Typically only when bed bugs are starved will they feed during daylight hours.
8. Bed bugs are considered an important vector of several diseases of human.
9. Bed bugs are capable of detecting the presence of host cues over considerable distance (about 15 feet away for CO2 and for heat).
10. Bed bug droppings are black or nearly black in color and often will often appear as dots or specks that are similar in appearance to a dried drop of ink. The feces are digested blood.
11. One of the possible reasons for the current increase in bed bug problems in the U.S. is the change from using residual insecticides for cockroach control to the use of baits.
12. One estimate is that on an average it will take only 2 weeks from an initial infestation to develop to the point where it is detected by the resident.
13. Once bedbugs become established, any control effort that does not include concurrent inspection of all units in a multiunit facility, together with a coordinated program of treatment and occupant education is usually doomed to fail.
14. A common complaint is spider bites. In actuality spiders biting humans is very rare. Regardless spider bites are characterized by 2 tiny puncture marks on the skin corresponding to their paired fangs.
15. . In an infested structure, less than 10% of the bedbugs are typically found on the bed.
16. . Bed bugs are relatively small and flat and as a result they have a relatively large area where water can evaporate from their body and subsequently are quite susceptible to dehydration.
17. Silica gel, boric acid, and diatomaceous earth will provide long-term control, provided they are used in an environment with low humidity.and have very low repellency, a long residual life, and can provide good control if thoroughly applied to cracks and crevices. However, they are typically white in color and may leave the surface of items with an undesirable film unless they are carefully applied.
18. Insecticides currently labeled for ULV, aerosols and foggers have little or no residual effects on bedbugs. Most will seldom penetrate cryptic bed bug harborages. If directly injected into harborages, these products may stimulate some bedbugs to become active and move out into the open, allowing them to be more readily seen.
19. Bed bugs will commonly travel 20 to 40 feet from an established harborage to feed on a host.
20. Bed bugs are quite susceptible to heat and can be killed on clothing placed in clothes drier.
21. Bed bug mattress covers are an effective means of controlling an infestation of these pests in a structure.
22. Insecticides containing natural pyrethrins will repel insects and can “knock down” bed bugs for a period of time, but natural pyrethrins quickly deteriorate and does not provide the necessary residual action of some other materials.
23. Bed bugs have been found naturally infected with at least 30 human pathogens but have never been proven to transmit any of them biologically or mechanically. There are some indications that bed bugs may be a vector for hepatitis B and Chagas Disease.
24.Tent funigation with Vikane is recommended by a number of companies for bedbug control. Many feel if used as recommenmded, it should give 100% control.
Flea Biology and Control
By Dr. Richard and Patricia Kaae
Adult fleas are small, wingless critters with backward projecting spines on their flattened highly sclerotized (hard) body. All these characteristics are well suited for their ectoparasitic way of life. Of course, there would be no advantage in being large as the host could easily remove such a creature. Insect wings are generally most useful in either finding a mate, food or seeking a favorable environment and all these factors seem to be readily available on the flea’s host. The backwards-projecting spines make it more difficult for the host to scratch-out or remove an adult flea because the spines can readily lodge in hair or feathers. Of course, forward projecting spines would hinder the flea’s movement through the forest of hair of many hosts. The adult flea is flattened from side to side thus allowing it to easily move through the host. Finally, a heavy sclerotized or thick exoskeleton makes it more difficult for the host to kill adult fleas by scratching or biting.
Fleas have a limited sense of smell with small antennae concealed in grooves. However, they can readily detect carbon dioxide thus possibly explaining why fleas get so excited and jump wildly when coming in contact with breath. Depending on the species, fleas may or may not have eyes but even in the case of the former they are thought to have a poor sense of vision, which is limited to detecting changing pattern of light and shadows. Their bodies are covered by a variety of sensory hairs and spines that can detect the vibrations of other animals. As a result of these various structures fleas are well adapted for detecting a host using smell (CO2), vibrations and shadows. This ability was recently illustrated by an experiment conducted on rabbit fleas. Two hundred and seventy-five adult fleas were marked and randomly released in an 18,000 square foot enclosed field. Then three rabbits were released in the field. After a few days over half of the released fleas were found on the rabbit.
Worldwide there are over 1,600 species of fleas while in the US there are a few hundred. Most species are somewhat host specific and this alone can be used to a degree for identification (rabbit fleas occur mainly on rabbits, mice fleas occur primarily on mice, etc.). Regardless of this large number some species are much more commonly encountered and of more economic importance than others. The following is meant to be a beginning source for the identification of some of the more common economic species. The main criteria that are used for species identification in fleas are the presence or absence and shape of the pronotal and genal combs (Figure 1), length of the labial palps, shape of the head and a few other minor morphological characteristics.
Figure 1. The head and thorax of a cat flea illustrating the teeth of the genal and pronotal combs. Images courtesy of Department of Parasitology, University of Sao Paulo, Brazil.
Based on structural differences the fleas that are commonly encountered in the US fall into 3 groups, mainly those which possess a genal and pronotal comb, those that only have a pronotal comb and those that lack both types of combs. The following key can be used to identify many of the common fleas found in the US.
Fleas with a Genal and Pronotal Comb
The cat flea (Ctenocephalides felis) and the dog flea (Ctenocephalides canis) obviously belong to the same genus and are very similar in appearance. They can be distinguished from other common fleas by the presence of both genal and pronotal combs. The mouse flea and rabbit fleas share this characteristic and can be distinguished from the cat and dog flea later. The main characteristic that is used to distinguish a cat flea from dog fleas is that in the dog flea the first tooth on the genal comb is distinctly shorter than the second while in the cat fleas they are of equal length. (Figure 2).
Cat Flea Dog Flea
Figure 2. A comparison of the cat and dog fleas. Note in the cat flea the first and second teeth on the genal combs are of equal length, while in the dog flea the first is significantly shorter than the second. Images courtesy of Department of Parasitology, University of Sao Paulo, Brazil.
As previously mentioned the rabbit and mouse fleas also possess a genal and pronotal comb. The mouse flea can be distinguish from the above 2 fleas and the rabbit flea by the fact that it lacks eyes (Figure 3).
Figure 4. A mouse flea (Leptopsylla segnis). Distinguished by the presence of a genal and pronotal comb and absence of an eye.
As with the above 3 species, the rabbit flea possesses a genal and pronotal comb but the distinguishing characteristic is that the genal comb is almost vertical in the rabbit flea (Figure 54) as opposed to a horizontal position in the other 3 species. The teeth on the comb are blunt in the rabbit flea.
Figure 4. Rabbit flea with blunt teeth on a nearly vertical genal comb.
Common Fleas with Only a Pronotal Comb
The northern rat flea (Figure 5) and the ground squirrel flea possess only a pronotal comb. No image is available for the ground squirrel flea.
Figure 5. The northern rat flea, Nosopsyllus fasciatus, is distinguished by lacking a genal comb.
Common Fleas Lacking Both a Genal and Pronotal Comb.
The stick tight flea (Figure 6) is characterized by the absence of a genal and pronotal comb and presence of an angular head and contracted thoracic area.
Figure 6. Stick tight flea. Image courtesy of Department of Parasitology, University of Sao Paulo, Brazil.
The Oriental rat flea, Xenopsylla chelopis, (Figure 7) is characterized by the absence of a genal and pronotal comb, and the mesonotum is divided by a thickening and the ocular bristle inserted in front of the eyes.
Figure 7. Oriental rat flea. Image courtesy of Department of Parasitology, University of Sao Paulo, Brazil.
The human flea, Pulex irritant (Figure 8) is characterized by a lack of genal and pronotal combs, and no mesonotum division and the ocular bristle located below the eye.
Figure 8. Human flea. Image courtesy of Department of Parasitology, University of Sao Paulo, Brazil.
FLEA BIOLOGY. Fleas are often found on birds and mammals with over 2,000-3,000 species occurring worldwide. Based on feeding habits, there are 3 main types of fleas. The first type does not attach to the host while feeding. These fleas are easily transmitted from one host to another and most belong in this category. The second type includes stationary females that are anchored by their mouthparts while feeding on the host. The third includes gravid females that develop under the host's skin and maintain a breathing pore to the outside.
The life cycles of most common fleas found in the US are somewhat similar. The following is based on the most common flea found on pets, namely the cat flea, Ctenocephalides felis (Figure 2). As with most fleas in temperate areas of the world cat fleas infestations tend to be seasonal reaching peak population in the summer months and in the colder areas dropping to almost non-existent in the winter months. As with all insects the length of the life cycle and therefore rate of reproduction is directly proportional to prevailing temperatures. To a point the warmer the temperature the faster an insect completes its life cycle. Also outdoors colder temperatures and rain greatly increase the mortality rate of fleas. Of course if pets are confined to indoor conditions or someone live in warmer tropical areas flea season can be year around.
The flea spends most of its adult stage on the host. As with most fleas the cat flea has preferred hosts (dog and cats) but in the absence of these will find and feed on other warm-blooded animals, including humans.
The mouthparts of adult fleas are adapted for slicing the skin and siphoning blood. In order to produce eggs a female flea must have a daily blood meal. Once fed she typically deposit her eggs on the host but most will drop off, as they are relative dry. The eggs are relatively large for such small insects, about the size of a grain of salt or approximately 1/12th the size of the adult flee. They are oval and rounded on both ends. A female flea deposits several eggs a day but since they are long lived she is capable of producing 300 to 400 eggs during her lifetime. When an infested pet (such as a cat during fleas season) sleeps on a table or other surface and leaves, it almost looks as if someone has taken salt and pepper and sprinkled it on this surface. This is called the salt and pepper effect. Of course the salt is the fleas’ eggs and the pepper is the feces of the adult fleas.
Once deposited the eggs hatch in 2 to 12 days depending on prevailing temperatures. As previously discussed the warmer the prevailing temperature (to a point) the faster the eggs hatch. Optimum development for fleas typically occurs in locations protected from rainfall and sunlight with a relative humidity of at least 75% and temperatures between 70 to 90 F.
The flea larva is elongated, legless with a well-developed head capsule and elongated sparse hairs on the body. When disturbed they will characteristically flip in circles. The larval stage (Figure 9) is a scavenger feeding on any of a variety organic matter including dander, feces, food particles and other organic matter. One of main ingredients in their diet is the adult feces that is quite high in protein. Adult fleas bite and feed many more times than are needed to fulfill their nutritional requirements. As a result their feces is very high in partially or undigested blood. This is a very efficient system. As the host walks around it is not only dropping flea eggs into the environment but is also dropping the main ingredient of the larval diet.
Figure 9. The larval stage of a flea, a scavenger. Image courtesy of CDC Healthwise Photo Library.
The larval stage may be completed in as little as 9 days or under unfavorable conditions can be extended as long as 200. Larval development is normally restricted to protected places where there is at least 75% relative humidity. At the end of this active feeding stage after the larva has reached full growth, it spins a cocoon around its body and pupates. The pupal cocoon (Figure 10) typically is covered by bits of their environment including such materials as lint, hair, dirt and sand. Again the length development of the pupal stage is quit variable but at room temperature approaches 2 weeks.
Figure 10. The pupa in case (left). Pupa (right) removed from case. Image courtesy of Department of Parasitology, University of Sao Paulo, Brazil
Once fleas emerge from the pupae they remain in the silken cocoons until the presence of an approaching host trigger them out. Prior to emergence from the cocoon an adult flea can survive for an extended period of time (350 days or more). However, once emerged the adult must feed or it will die in a few days. If continuously fed some species can live for a year or more. The longest recorded life cycle of a flea is 996 days for Pulex irritans, the human flea.
FREQUENTLY ASKED QUESTIONS
A few occurrences or questions homeowners commonly encounter or ask can be explained by flea biology.
Scenario #1. Prior to taking their German Sheppard with them on a 4-week vacation, homeowners have a little problem with flea bites. They return to find dozens of fleas jumping all over their legs. Answer. Prior to leaving, most of the fleas that emerged from their pupae fed on the preferred host--the dog. While they were gone, many fleas completed their life cycle as the host presence was not necessary; the larvae are scavengers. Because no one was home, the adult fleas that emerged remained in their loose cocoons. Upon their return, the homeowners’ vibrations triggered the fleas out of their cocoons. Of course one solution would be to send the dog in first to collect all the waiting fleas (joke).
Scenario #2. Someone has a flea problem in their home but does not have any pets. In this case, there was probably a flea-ridden animal in or under the home at one time. Upon its departure the fleas were left to seek the only available host, the human. Possibly someone had spent a few days in the home with their pet dog or possibly there was a litter of kittens below the house. There may not be many fleas in the home with this type of situation, but those that are left will make their presence known and will bite the homeowner.
Question #1. I am frequently bitten by fleas and my wife is almost never attacked. Why? Answer. Blood feeding insects such as fleas and mosquitoes are attracted to their victim by chemicals such as those found in sweat and breath (CO2). People obviously smell different and are more or less attractive. Amazingly, there even seems to be a difference in attractiveness to individuals depending on the geographical area. We have noticed that mosquitoes are more attracted to my wife in Thailand but are more attracted to me in Central America. Individual sensitivity to bites is another factor, which can partially answer this dilemma. To some bites are extremely annoying while to others they are hardly noticed. The difference is due to an allergic reaction to the saliva that is injected when a flea feeds. There are different degrees of allergic reactions amongst different individuals. The function of the saliva is to keep blood flowing while the flea feeds. It contains an anticoagulant.
Question #2. I just moved into an apartment and there were hundreds of fleas. This is especially puzzling since it has been vacant for 2 months and it was treated for fleas when the previous tenant moved. Answer. The people who lived there before you probably had pets. The adult fleas you are seeing are those that have not emerged from their cocoons. Remember adult fleas can remain alive in this condition for up to 12 months or so. If the house was previously treated, treatment probably did not penetrate the carpet where these larvae and pupae were developing.
Question #3. I have bombed my house three times this month and still have a problem with fleas. Why? Insecticide bombs do not to penetrate and would not reach developing flea larvae and pupae deep in the rugs. If you did not treat your yard it is possible that new adult fleas could be coming into your house on you or your pet.
Questions #4. Why do fleas seem to be more of a problem in my beach house as opposed to my home in the inland valley? Answer. First of all part of the answer may be due to differences in climate. Temperatures at the beach tend to be milder and therefore favorable for flea development and survival than those in inland areas. Beach areas tend to also have a higher humidity, which is also favorable for flea development and survival. Finally people frequently confuse sand fleas with true fleas.
Question #5. What are sand fleas? "Sand fleas" or "beach fleas" are common names for small orange crustaceans called amphipods found along the beach. They are distant non-insect relatives of true fleas, and do not even bite. Also, some people may refer to fleas that just happen to be developing in sandy areas as "sand fleas".
FLEA DISEASE AND OTHER MALADIES.
Fleas are common vectors of some very notorious diseases. The most well known worldwide disease is the Bubonic Plague (Figure 11). In the sixth and fourteenth century this disease swept the earth with hundred year plagues killing approximately 1/4 the population of Europe. The most recent epidemic of this disease was in Northern China at the turn of the 20th century. The plague is still present today and is mostly harbored in rodent populations (Sylvatic plague).
Figure 11. Worldwide distribution of plague. Image Courtesy of the Center for Disease Control and Prevention.
New Mexico has the highest incidence of the disease in the United States, especially in American Indian reservations. There are locations in California where plaque is known to periodically occur in the rodent populations. Some of these locations include Diamond Bar, Anaheim Hills, Griffith Park and Angeles Crest. The rodents in these areas (ground squirrels and voles) are closely monitored by the Health Department during the summer months for any signs of plaque. If found the situation is quickly corrected by rodent eradication and flea control. Through these efforts plague is kept in check in California and other states. Annually we average less than one human case of this disease in California (Figure 12).
Figure 12. Distribution of plague in the Western US by County. Image courtesy of The Center for Disease Control and Prevention.
The symptoms of the disease include a rapid onset, with an incubation period of only 2 to 10 days, a fever reaching up to 104oF, and flu-like nausea. In some cases, buboes (hence the name bubonic plague) form from swollen lymph nodes in the pelvic area, groin, armpits, and back of neck. The buboes form on the second day after symptoms appear and are very tender and sore. The disease can then progress to the blood (septicemia plague) system where the spleen and liver are affected. In the third stage, which is 90% lethal, the disease progresses to the respiratory tract (pneumonic plague)? This is an extremely contagious stage and can be transmitted through coughing. Handling of any wild animals should not be undertaken unless absolutely necessary. Veterinarians appear to be the group most at risk for contracting this disease.
Both male and female fleas transmit the disease while feeding. This occurs due to a plague bacterial buildup in the gut of the insect and subsequent regurgitation of the blockage by the flea into the host while feeding. Plague season typically occurs during the summer months. Apparently higher temperatures are necessary for a bacterial blockage to occur in the flea’s gut. Because of the blockage, the flea does not "feel" full and jumps from host to host in order to feed more. This, of course, spreads the disease even further. There is a vaccine available, but it is not recommended because of severe side effects. Currently, only military personnel are given this vaccine.
Murine Typhus (Rickettsia typhi) is another disease that fleas transmit and is usually found in rural areas. The fleas responsible for this disease are the same as those that vector plague. Antibiotics are effective when given at the first onset of symptoms.
Feeding Effect. With very heavy prolonged flea infestations pets can develop anemia. In extreme cases a pet may harbor an infestation of several hundred fleas. In such cases the animal’s immune system can be severely damaged resulting in death. Heavy infestations are more common in kittens and puppies as they are less proficient than adults in mechanically removing fleas by biting and scratching.
Pets may develop allergic reactions to flea bites. This is especially true in older pets, which have a long history of flea infestations. As with most allergic reactions the tendency to do so is genetically linked. It is not uncommon in households with many cats for a few to develop this type of allergies while others harboring approximately the same number of fleas are apparently unaffected. In cases of extreme allergic reactions the animal will lose large amounts of hair, especially around the rump and on the tail. One of our black cats (we call him old bald butt Bart) develops this condition every flea season. Once such an allergy develops the bite of a single flea can initiate the condition. In addition to hair lost the animal may develop reddened skin and small scabs over much of his or her body. The latter are partially due to the excessive scratching of the animal. Normally a veterinarian can be corrected allergic reactions by injection and oral administration of cortisones and flea control.
Fleas can serves as an intermediate host for dog and cat tapeworms. Fleas are typically infested with the cyst when the larvae feed on the feces of a tapeworm infested host. The cyst form is subsequently passed on to the adult flea. Consuming the adult flea can in turn infest a cat, dog or even small child. Once consumed the worm form emerges from the cyst and begins to feed in the digestive tract. Tapeworm feed by absorbing nutrients. This may result in loss of weight and a rundown condition in the host. An infestation is usually diagnosed by the presence of the crawling almost square worms that are about the size of a grain of rice in the feces of the host.
The Oriental rat flea, Xenopsylla cheopis (Figure 13), and northern rat flea, Nosopsyllus fasciatus are the primary vectors of the plague. These fleas attack the Norway rat, roof rat, and black rat, all of which are commonly associated with humans. They also are typically found on ground squirrels, wood rats, and prairie dogs.
Figure 13. The Oriental rat flea. Image courtesy of Department of Parasitology, University of Sao Paulo, Brazil.
The 2 major fleas that are of household concern are the dog flea, Ctenocephalides canis, and the cat flea C. felis, respectively (Figure 2). Both of these are problematic for pets in the US, with some animals having severe allergic reactions. Typical symptoms of an allergic reaction to fleas in cats and dogs include a loss of hair, especially around the upper rump, flaky dry skin and many bumps and scratches due to the pet’s attempts to remove the fleas. Older animals are typically most susceptible. This is especially true if the animal has had a history of flea infestations. In some cases the bite of a single flea can result in these symptoms if the animal is highly allergic. Treatment for allergic reactions includes flea control and cortisone shots by a veterinarian.
Typically when these 2 species bite humans most bites occur around the lower legs (Figure 14). As with some other fleas when they bite they will feed many more than needed for nourishment. The bites shown on the above illustration are those from a few fleas (possibly one).
Figure 13. Typical cat flea bites occurring on lower legs. Image Courtesy of Vopak Inc.
The human flea, Pulex irritans (Figure 14), is found all over the world. Besides humans, it infests cats, dogs and many other animals, particularly pigs. It breeds profusely in pigsties, and people working in them can pick up large numbers of fleas and start infestations in their own homes. The human flea is usually the most important flea in farm areas; while the bite of cat fleas tends to be concentrated on the lower part of the legs, those of the human flea may be spread all over the body.
Figure 14. The human flea. Image courtesy of Department of Parasitology, University of Sao Paulo, Brazil.
The human flea is the species that was used in the 1800’s in European flea circuses. They were chosen for their exceptional ability to jump (over 6 inches high and 13 inches laterally) and supposed strength. They can pull over 400 time their own weight. They later fact is especially impressive since the average human cannot pull much over once their weight. In the circuses these fleas performed a variety of acrobatic stunts including pulling tiny carts through the streets of miniature villages. These circuses eventually became sideshows in fairs and informal outdoor markets. These events became known as flea markets, a term we are all familiar with today.
The sticktight flea, Echidnophaga gallinacea, is one of the smaller fleas with males measuring less than 1mm (Figure 15). The adult flea attaches itself on the head or neck of domestic fowl, sometimes causing ulcers. Females lay their eggs in the ulcers and the hatching larvae fall to the ground and feed on decaying plant material. Sticktight fleas can become quite abundant in poultry yards and adjacent building. Besides birds they can attack humans, rat, cats, dogs, and many other mammals. They are potential vectors of plague but their habit of remaining tightly to one host greatly reduces this possibility.
Figure 15. The adult of the sticktight flea, a poultry pest.
The chigoe, Tunga penetrans, (Figure 16) is also known as chiggers, jiggers, chique and sand fleas. Some of these latter names can be misleading, as these are neither true chiggers, which are of course mites nor true sand fleas, which are actually crustaceans. This is a tiny burrowing flea that is found in the tropical areas of North and South America, Africa and the West Indies. It is said to have inspired the sailor’s saying, “I’ll be jiggered”.
Figure 16. The adult chigoe, also known as a jigger or sand flea. Image courtesy of Department of Parasitology, University of Sao Paulo, Brazil.
An infestation of these fleas is referred to as tungiasis. Gonzalez Fernandez De Oviedo y Valdes noted the earliest report of tungiasis at the turn of the 16th Century when Spanish conquerors of the crew of the Santa Maria were shipwrecked on Haiti and became infested with the disease. A few years later, the Spanish conqueror Gonzalo Ximenes de Quesada reported an entire village in Colombia that had been abandoned by its inhabitants due to this disease. Consequently, his soldiers became so infected with the disease that they could barely walk. In the 17th Century, Aleixo de Abreu, a Portuguese physician working in the Brazilian government, provided the world with the first scientific description.
The sand flea is normally found in the sandy terrain of warm, dry climates. It prefers deserts, beaches, stables, stock farms, and the soil and dust close to farms. While both male and female sand fleas intermittently feed on their warm-blooded hosts, it is the pregnant female flea that burrows into the skin of the host and causes the cutaneous lesion. She does not have any specialized burrowing organs; rather, she simply attaches to the skin by her anchoring mouth and claws and burrows violently into the epidermis. Since this process is painless, it is thought that the flea may release some type of tissue dissolving enzymes. After penetrating the skin, she leaves her posterior (rear) end exposed (Figure 17). The "black dot" of the nodule is this posterior end of the flea sticking out. The opening provides the flea with air and an exit route for feces and eggs. With its head deep into the skin, the flea begins to feed on the host's blood and enlarges up to 1cm in diameter. Over the next two weeks, over 100 eggs are released through the exposed opening and fall to the ground. The flea then dies and is slowly sloughed by the host's skin. The eggs hatch on the ground in 3-4 days. In the next 3-4 weeks, they go through their larval and pupal stages and become adults. The complete life cycle of these fleas is about one month.
Figure 17. An adult chigoe buried into the skin. Image courtesy of Department of Parasitology, Sao Paulo, Brazil.
The first evidence of infestation by this sand flea is a tiny black dot on the skin at the point of penetration. Because the flea is a poor jumper, most lesions occur on the feet (Figure 18), often on the soles, the toe webs, and around or under the toenails. Among natives who frequently squat, however, the buttocks and scrotal sac can be involved. A small, inflammatory papule with a central black dot forms early. Within the next few weeks, the papule slowly enlarges into a white, pea-sized nodule with well-defined borders between 4-10mm in diameter. This lesion can range from asymptomatic to pruritic to extremely painful. Multiple/severe infestations may result in a cluster of nodules with a honeycomb appearance. Heavy infestations may lead to severe inflammation, ulceration, and fibrosis. Lymphangitis, gangrene, sepsis, the loss of toenails, autoamputation of the toes, and death may also occur. In most cases, however, this lesion heals without further complications. Nonetheless, the risk of secondary infection is high. Tetanus is a common secondary infection that has reported associations with death. People should avoid walking with bare feet where these fleas are known to occur. Of course dogs and other pets are frequently infected (Figure 19).
Figure 18. Ulcers on the feet due to burrowing chigoe fleas. Image courtesy of Department of Parasitology, Sao Paulo, Brazil.
Figure 19. Ulcer on dog legs due to feeding of chigoe flea. Image courtesy of Department of Parasitology, Sao Paulo Brazil.
The cat flea is the most common flea found feeding on hosts such as domestic pets, humans, rodents, raccoons, and other wild animals. Successful flea control begins with identification of the species involved, determining the source of infestation and understanding the flea life cycle.
The first step is to interviews the building occupants concerning household practices and recent animal visitors. This will alert the professional as to hot spots and potential sources of the infestation. Next a thorough interior inspection should be made to determine the presence of fleas, concentrating on where domestic animals sleep or common avenues of travel. This can be accomplished by using a vacuum device, a white-sock test or a light trap, as well as inspecting domestic animals thoroughly. Finally a thorough exterior inspection should be performed, especially where domestic animals frequent or wild animals nest, such as under porches, crawl spaces, perimeter fence areas, kennel areas, and overgrown vegetation (shrubbery).
Successful control typically encompasses eradication of the fleas on the pet, in the home and in outdoor locations. Control on the pet alone is typically futile since the eggs, larvae and pupae are found off the host thus continually providing a source of new adult fleas for reinfestation.
Treatment of Pets. There are an infinite number of products and devices available for control of fleas on pets. Although the pest control operator typically does not (and should not) become directly involved in this aspect of flea control, it is to his or her advantage to be aware of the various means that are available for this purpose.
Flea combs. These devices are not very effective and when used properly will only remove 10 to 60% of the adult fleas. This method is also very time-consuming.
Shampoos. These products tend to be a temporary solution to an on-going problem. One advantage is that they do not only kill adult fleas but also remove dried skin and fleas feces that eventually fall to the ground and serve as food for the flea larvae. Typically with flea shampoos the animal should be thoroughly lathered and rinsed after 15 minutes. There are a variety of products available containing different active ingredients. Pyrethrins are derived from Chrysanthemum flower heads. They kill adult fleas quickly but have essentially no residual activity or lasting effects. Pyrethroids are synthetically produced and have a longer residual activity. Carbaryl is a carbamate insecticide that has a long history in pest control. This material is somewhat toxic to cats so label instructions should be carefully followed. Citrus peel derivatives, such as D-limonene are used in some shampoo products, which are fairly mild making them useful for use on kittens and puppies as well as in household with new babies. However, in some cases cats may exhibit allergic reactions to these materials. Pennyroyal oil is another natural product used in pet shampoos. Pulegone, the active ingredient in this oil can be toxic to animals if misused resulting in any of a number of side effect including death due to liver failure. If used label directions should be followed carefully.
Topical Applications. Some of the newest products for flea control are imidactloprid (Advantage), fipronil (Frontline) and (Program). Advantage and Frontline are spot-on oils and are applies monthly as a small drop to the back of the neck to prevent removal by grooming. The products quickly spread over the body due to movement of the animal. They are nontoxic to mammals and kill most of the fleas on the animal within 24 hours. Advantage provides approximately 98% control for the first 3 week on dogs and cats. Control drops slightly during the 4 week. Frontline provides a somewhat longer residual activity with a 98% kill for up to 8 and 6 weeks on dogs and cats, respectively.
Lufenuron (Program) attacks the problem from a different perspective than Advantage or Frontline. The active ingredient in this product is a chitin inhibitor. Chitin is the main protein in the insect’s exoskeleton that gives it strength. As with the other above-mentioned products Program is usually applied on a monthly basis. It does not kill the adult fleas but once the fleas feed on the treated pet the active ingredient prevents chitin from forming in the flea’s eggs. As a result when the eggs are produced they break due to the lack of chitin in the shell. In order to be effective Program must be used immediately prior and during the entire flea season. The idea is to prevent the flea infestations from developing in the first place.
Flea collars. Most studies indicate that flea collars are relative ineffective when compared to many other available means of control. This is especially true when ultrasonic flea collars are concerned. These devices have been found to have no significant effect on fleas.
Control in the Home and Yard
It is worthwhile to discuss with family members the areas in and around the home where pets spend most of their time sleeping and resting. Hot spots of activity can be determined by placing white socks over shoes and walking throughout the residence. Hot spots in homes with dogs are usually areas where the animals go in and out of the home, eat, sleep and spend time with the family. Cats frequent similar areas but should include high areas including tops of refrigerators, cabinets and bookcases. There are commercially available flea traps (Happy Jack and pulvex), which can be useful for monitoring flea populations. Research indicates that the larva do not move far from the site of hatching, especially if food is available.
Sanitation. Sanitation is one of the first steps to effective flea management in the home. Vacuuming on a regular basis (a minimum of every other day) will remove many of the various stages, dried blood and other sources of larval food from the carpet or areas where the pets sleep. Prior to any pesticide application the carpet should be vacuumed thoroughly with a beater-bar type vacuum. This will open up the carpets nap to allow treatment to reach deeper into the carpet where much of the infestation occurs. Research indicates that approximately 83% of the larvae spend most of their time deep in the carpet at the base of the fiber. At pupation the larvae move up the carpet fiber spinning a camouflaging cocoon around itself. Vacuuming is especially important where lint and pet hairs accumulate along baseboards, around carpet edges, on ventilators, around floor heaters, in floor cracks and under and in furniture where pets sleep. After vacuuming, the vacuum bags should be discarded in an outdoor trash container. Thorough vacuuming can be an effective tool in a flea pest management system. All pet bedding should be thoroughly washed on a regular basis.
Trimming lawns and weeds will create a drier, less-ideal environment for flea larvae. It can also be beneficial to avoid piles of sand and gravel around the home. Dogs should be prevented from roaming freely in and outside the yard, especially in heavily weeded areas or other areas where they may encounter reinfesting fleas. Areas that are difficult to access such as crawl spaces or attics under a home should be sealed to prevent pet entry. A crawl space is an ideal location for fleas to breed. It is also important to eliminate possible infestations of wild animals such as raccoons, opossum rats and birds near the premises.
Chemical Control.Even though much of the above can useful in preventing and reducing flea infestations in the home chemical control is the ultimate weapon. There are dozens of chemicals registered for flea control and a discussion of all these are beyond the scope of this manuscript. We have tried to include those that are most commonly used and are not in the business of recommending any.
Before treating, the homeowner should remove all toys and pillows off the floor or carpet, from under beds and furniture and on closet floors. All areas frequented by pets (e.g. table tops, refrigerator tops, window sills, counter, etc.) should be thoroughly cleaned. All pets should be removed from the premises prior to treatment. This would include covering aquariums.
Insect Growth Regulators (IGRs). This is a relatively new group of chemicals with a totally different mode of action than the so called conventional insecticides. Although the growth regulators do eventually kill their primary function is to disrupt the growth and molting process. In most cases this results in malformed insects that cannot function properly. In order to understand how these products work a brief description of the function of the hormones that control growth and molting in insects is needed.
Hormones are chemical substances that are introduced into the blood and subsequently to other parts of the body where they produce some effect on physiological processes. In insects there are 3 glands that secrete hormones that regulate growth and molting. These are the brain hormone, ecdysone and the juvenile hormone.
The brain hormone, which is secreted by a gland at the base of the brain, plays an important role in molting by stimulating a pair of glands in the prothorax to produce a second hormone called ecdysone or the molting hormone. Ecdysone functions to control when molting occurs and the rate of growth of insects. The third hormone, juvenile hormone or JH is secreted by another gland in the brain and functions to determine what an insect will molt into. If there is a high level of juvenile hormone during the molting process the insect will stay in a juvenile stage-e.g.-larva to larva, nymph to nymph. If there is a low level the insect will advance in stage.
Scientists have chemically identified some of these hormones in key insects. Once the chemical structure of a hormone is known it can be synthetically produced in the laboratory. It turns out that if abnormal amounts of a synthetically produced hormone are applied to an insect then abnormal molts occur. In some cases monstrous, deformed insects occur (e.g.-half larva half pupa). There hasn’t been much done with the brain hormone. It typically has too complex of a molecule, which makes it too hard to identify or synthetically produce in the laboratory. Ecdysone typically has a steroid component to its molecule. Since humans also have steroids in their bodies this might makes it difficult to get these types of chemicals registered as a useable pesticide with the EPA.
The juvenile hormone is the main chemical that has been used as an insecticide. Actually the juvenile hormone mimics that are used do not have the same chemical structure as what occurs naturally in the insect’s body. The main reason is that a natural occurring chemical cannot be patented. As a consequence the chemical companies that produce these pesticides change the chemical structure a little when they synthetically produced them in order to patent the compound and protect their investments. As a group the juvenile hormone mimics are referred to as Insect Growth Regulators.
There are currently a few of these chemicals that are registered for flea control. One of the disadvantages of some of the IGRs (for outdoor use) is that they tend to breakdown when exposed to sunlight. However, a recent study using pyriproxfen (Nylar) reported it to be stable in sunlight when used outdoors for three weeks. In this study it gave 90% control of developing fleas. Methoprene (Precor) is reportedly another effective IGR for flea control.
A disadvantage of these types of chemical is that they do not kill adult insects which of course do not molt. As a consequence an adulticide is also mixed in the spray tank when using IGRs.
If the pets spend any time outdoor treatment of the yard is needed. When doing so the preferred breeding locations, areas where the animals spend most of their time and biology of the fleas should be considered. Again outdoors fleas typically breed in shaded, moist but not wet locations. Keeping this in mind it does little good and is a waste of time and money to treat the whole yard. Cats using sand boxes and dogs sleeping under shrubs or in crawls spaces or garages provide a reservoir for fleas. Animal pens, kennels, doghouses, sandy soil and gravel driveway are other important sources to consider. Clean and sweep porches, mow lawns and soak dry soil with water before treating to bring flea larvae up to the surface. Commonly used insecticides for outdoors treatment include fenvalerate, carbaryl, diazinon, popoxur, resmethrin, Knox Out and bendiocarb.
Questions for continuing education.
25. The “salt and pepper effect” refers to the eggs and feces of adult fleas.
26. The larval stage of a flea feeds on the host in various places, including loose skin.
27. The adult chigoe flea typically burrows beneath the toenails or between the toes causing considerable pain and sometimes even loss of the toes.
28. The dog flea is the most common species of flea found on dogs in Southern California.
29. Once emerges from their cocoon adult fleas can live several months without feeding.
30. Once the cat flea emerges from the pupae it remains in a loose cocoon until triggered out by a passing host.
31. The dog and cat flea are more attracted to dogs and cats than humans.
32. Plague when present in rodent populations is called Sylvatic plague.
33. Typical symptoms of a dog’s or cat’s allergic reaction to fleabites include dry flaky skin and loss of hair, especially around the rump area.
34. Fleas combs and flea collars are very effective tools for control of fleas on pet
35. Advantage works primarily by preventing the production of chitin in the eggs.
36. After they are deposited, most of the eggs of a cat flea drop remain on the host.
37. Bites from the human fleas typically occur around the ankles and lower legs.
38. IGRs are an effective means of killing adult fleas.
40. The backwards-projecting flea spines make it more difficult for the host to scratch-out or remove an adult flea because the spines can readily lodge in hair or feathers. Of course, forward projecting spines would hinder the flea’s movement through the forest of hair of many hosts.
41. The adult flea is flattened from side to side thus allowing it to easily move through the host. Finally, a heavy sclerotized or thick exoskeleton makes it more difficult for the host to kill adult fleas by scratching or biting.
Image Courtesy of L A County Agricultural Commissioner's Office.
All lice are ectoparasites; they live and feed on the outside of their host's body. Although lice can have detrimental effects on the host, an infestation is rarely lethal. All ectoparasites have a number of advantageous characteristics in common. Most are quite small, flattened, wingless and possess backward-projecting spines on their bodies. Their small size makes it more difficult for the host to detect their presence. Being flattened and possessing backward projecting spines that can lodge in hairs or feathers makes it more difficult to dislodge them from the host. Finally, because the host represents an unlimited source of food and typically is infested with many of these ectoparasites, there is no need for wings to find food or a mate.
ORDER: MALLOPHAGA (CHEWING LICE)
There are 2 orders of lice, namely the chewing lice (Mallophaga) and the sucking lice (Anoplura). Chewing lice mainly attack birds although a few species inhabit mammals. They feed on hair, skin debris, blood serum and other body secretions. Eggs (nits) typically are glued either to feathers or hair. The life cycle is generally completed quite rapidly with many species developing from egg to adult in as little as 30 days. Chewing lice rarely leave the host, and some have been collected from museum specimens long after the death of the animal. All are host specific with none living on humans. Heavy infestations of chewing lice on poultry will result in loss of weight, reduced eggs production, and a general rundown condition in an animal’s health.
Typical Chewing Louse with Wide Head and Chewing Type Mouthparts. Image Courtesy of Department of Parasitology, Sao Paulo, Brazil.
ORDER: ANOPLURA (SUCKING LICE). The sucking lice share the characteristics of all ectoparasites but differ from chewing lice by their mouthparts and width of their heads. The chewing lice have large, heavily sclerotized chewing type mandibles for gnawing on the host. Consequently, they possess large muscles to move the mandibles and a large head that is needed to house the muscles. Sucking lice have small needle-like mouthparts to suck the blood of their host, and correspondingly have smaller mouthpart muscles and a smaller head. With Mallophaga and Anoplura, the head is wider and narrower than the thorax, respectively.
Comparison of Head Width of a Sucking Louse and Chewing Louse. Image Dr. Kaae
Crab Lice. Sucking lice are chiefly found feeding on mammals. Almost all are host specific with 3 types attacking humans. These are the head, body and crab lice. Crab lice (Pthirus pubis) or pubic lice attack humans and a few species of gorillas. Their broad flat bodies, overly large claws on the middle and hind legs combined with a characteristic sluggish behavior have resulted in the pubic louse also commonly referred to as crab lice. Infestations typically are restricted to the groin and perianal area of adult humans; however, with very heavy infestations, these lice can occur all over the body. If a child who hasn't reached puberty is attacked, the lice frequently are found on the eyelashes. Unfortunately in some cases, this is a sign of sexual abuse. Apparently finding these lice on the eyelid are a result of a critical factor in crab louse environment- namely the proper distance between and thickness of individual hairs. This distance and coarseness in eyelashes is ideal and consequently is occupied in the absence of pubic or other body hair in children.
Crab Louse. Image Courtesy of Los Angeles County Agricultural Commissioner’s Office.
Females lay a relatively small (at least when compared to many other insects) numbers of eggs (100 to 150) on body hairs. Development is quite rapid with a single life cycle being (eggs, nymphs and adult) completed in 30 to 40 days. Crab lice are nearly immobile and typically attach to body hairs with their opposing claw-like tarsi and tibia while feeding. They frequently become buried in their own excrement and can only live for a short time when off the host.
Because of host dependency and relative immobility, these lice normally are acquired by sleeping with an infested person. It is possible (but not probable) that crabs could be contacted from situations such as using the same shower towel immediately after an infested individual, using a toilet seat immediately after use by a heavily infested individual or similar situations. As might be expected, there is a correlation between the degree of crab louse infestations in the general public in a given area or during a particular era and the degree of sexual promiscuity. For example, crab lice infestations in the United States during the 1960’s and 1970’s were more common than today. The 60’s and the 70’s were the decades of social unrest, sexual experimentation and "free love." Today, we are hopefully much more careful because our awareness of more serious repercussions (AIDS, for example) has risen.
Crab lice do not vector any disease but can cause a rash and corresponding itching. As do most blood sucking insects, crabs inject a saliva when they feed that contains both an anticoagulant to keep the host's blood flowing and an anesthetic to minimize detection of their presence. Prolonged infestations of this species can result in subcutaneous blue spots (essentially bruising) ranging in size from 1/16 to 1/2 inch in diameter. Of course, the blue spots are a result of the anticoagulant in the saliva which results in bruising.
There are several products available for control of head lice. However, historically Kwell shampoo was probably the most effective material available. It is formulated as a lotion that contains the insecticide lindane.This insecticide has a relatively long residual activity and readily penetrates the skin, qualities that are not found in other products. Most doctors are not prescribing Kwell anymore because of possible side effects. There are new medications used recently that approach Kwell in effectiveness but do not have the same side effects. Permethrin based shampoos are currently one of the doctor prescribed products for control of crab lice.
Head Lice. Pediculus humanus capitis and Pediculus humanus humanus are different subspecies of the same species. When placed side by side, they look almost exactly alike; however, they have quite different types of biology and are easily to distinguish from crab lice (see above). It is thought that primitive humans were infested with head lice, but as we became more civilized and began wearing clothing, this opened up a different ecological niche that was ultimately occupied by body lice (these are found on clothing). Because they are both the same species, they are capable of inter-mating, but their offspring all exhibit characteristics of head lice, thus possibly reverting to the ancestral form.
Head lice were called mechanized dandruff during World War II; typically they were found above the shoulders on scalp hair, mustaches, sideburns and beards. In addition their presence could have been confused with moving dandruff. Heavily infested individuals may have the lice on all hairy parts of their bodies. They normally are gray colored but tend to take on the color of the hair they are infesting.
Top. Relative Size of Head Llce Adults. Image Courtesy CDC. Bottom. Closeup of Head Louse. Courtesy Gilles San Martin-CC SA 2.0
Their eggs (also referred to as nits) typically are deposited on the base of hair immediately next to the scalp. Generally, they hatch by the time the hair has grown ¼ inch. Occasionally head lice will lay their eggs on long hair that is lying on the scalp so unhatched eggs can be found some distance from the base of the hair. Lice use a cement to attach their eggs to hair. This cement is impervious to normal influences such as shampoo; consequently, the egg shells remain attached to the hair long after hatching. The empty egg shells are also referred to as nits. Head lice are significantly more prolific than crab lice because a single female can deposit up to 200 eggs and development can be completed in as little as 30 days. It should be noted an infestation of head lice has no correlation to unsanitary conditions as these lice have no socio-economic barriers. The rich are as likely to be infested with these pests as are the poor.
Nits on Human Hair. Image Courtesy of CDC.
There does seem to be a correlation between the probability of being infested with head lice and hair length. This is possibly due to the fact that head lice are more difficult to control in longer hair. Also it is less common to find head louse infestations in African-Americans: however, in Africa these lice readily attack black individuals. Individuals infested with these pests typically harbor only 10 to 20 lice, but in heavy infestations the hair can become matted with nits, nymphs and adult lice. Typically, only the head or scalp of the host is infested; however, these pests can occur in other hairy parts of the body such as leg hairs. As with the other species of lice that attack people, head lice feed on human blood and itching from louse bites is a common symptom of an infestation. Treatment typically includes application of topical insecticides such as permethrin. A variety of folk remedies are also common, some of which can be dangerous. The use of gasoline or other flammable liquids can be especially dangerous. A distant acquaintance of ours grew up in Turkey and as a kid on occasion had head lice treated by rinsing his hair with kerosene. Unfortunately, on one occasion he got too close to a flame. Forty years later he is still blind due to the accident.
Head Louse Bite on Neck . Image Courtesy of CDC.
Head-louse infestations are widely endemic and a worldwide problem in children. Such infestations are of some concern in public health. This concern unquestionably is due to the fact that infestations are much more common worldwide than the other species of lice that infest humans; however, unlike human body lice, head lice are not carriers of infectious diseases. Infestations from head lice are most commonly found on children ages 3 to 10 and their families. Females typically get head lice more often than males (again possibly due to difference of hair length). Infestation in individuals of Afro-Caribbean or other black descent is rare because possibly due hair consistency.
Lice in general pass through 3 stages of development--egg, nymphs and adults. From each egg or "nit" hatches one nymph that will grow passing through several nymphal instars to grow reach the adult stage. Full-grown head lice are about the size of a small grain of rice. Lice feed on blood once or more a day by piercing the skin with their tiny needle-like mouthparts.
Life Cycle Head Lice. Body Lice Similar. Public Domain.
Diagnosis. Generally speaking it is not difficult to diagnosis the presence of head lice. They will generally let you know of their presence. If needed, the entire scalp can be combed repeatedly with a louse comb to check for their presence. One effective way to determine the presence of living lice in children, especially those with long and/or curly/frizzy hair, is to part it and examine the scalp at short intervals. With each of the above techniques, attention should be paid to the area near the nape of the neck and close to the ears. Both processes should be accomplished with precision as the early instars and eggs of the lice are tiny. A magnifying glass may help with either process. .
It is worth noting that nits may be empty shells of a previous louse infestation, and their presence alone is not necessarily an accurate symptom of an active infestation. However, individuals with nits on their hair have a 35-40% chance of harboring living lice. If lice are detected on a child or any individual, the entire family should be checked (especially children up to the age of 13 years) as head louse infestations are readily transferable, especially within a family unit. Only those who are infested with living lice should be treated: however, louse control products that are registered for use in the U.S. should be considered safe. Excessive use of any pesticide product, if not needed, is a poor practice. As long as no living lice are detected on a suspected individual, they should be considered not having a head louse infestation. Accordingly, a child should be treated with a pediculicide only when living lice are detected on his/her hair (not because he/she has louse eggs/nits on the hair and not because the scalp is itchy.
Louse Comb. Image Courtesy of http://www.pediculosis-gesellschaft.de/
As previously indicated, the most characteristic symptom of infestation is itching on the head. Once infested by head lice, the degree significantly intensifies by the 3rd or 4th week. The victim’s reaction to the bite is normally very mild and can be rarely seen between the hairs. However, these symptoms can be seen on the nape of the neck in those individuals with long hair. In rare cases, excessive scratching and itching from the bites can lead to secondary infection. Even more rare are swelling of the lymph nodes and fever. Unlike body lice, head lice are not known to transmit any disease causing organism to humans. Head lice only cause symptoms with mild itching. More severe results are due to the victim's reaction to those symptoms. In the absence of discomfort or skin lesions, an infestation is therefore only a cosmetic and possible psychological problem for the victim.
Worldwide the number of cases of head louse infestations (or pediculosis) has increased tremendously since the middle 1960s annually reaching hundreds of millions. There is no product, treatment or method which will assures 100% destruction of various stages of this louse with a single treatment. However, there are several treatments that are available which will work with varying degrees of success. These methods include use of chemicals, natural products, shaving the head, nit combs, hot air treatment, silicone-based lotions and nit picking.
These insects are the most common insect pests of children. Approximately 40% of the children attending primary or secondary schools in the United States will be infested with these insects at one time or another. Teachers are trained to watch for children constantly itching their heads in class. If this behavior is observed, the child is sent to the school nurse who inspects for nits, especially around the upper nape area. If lice are found, the child is sent home and it then becomes the responsibility of the parent to control the lice before the child can be readmitted to school.
The widespread occurrence of these pests in schools partially is due to the way lice are spread from person to person. The most common vehicles of distribution are trading hats and combs, a common practice of school children. Also in many classrooms, hats and jacket are stored on adjacent or common hangers when not being worn. This gives any lice that may be on these articles a chance to crawl from one item to the next. Also, school children love to "sleep over" at friend’s houses. All participants at one slumber party can carry home head lice to their siblings or parents. The possibilities are staggering!
https://upload.wikimedia.org/wikipedia/commons/d/df/Head_louse_crawling_on_hairbrush.webm<iframe width="854" height="480" src="https://www.youtube.com/embed/_Q9r_POy5VA" frameborder="0" allowfullscreen></iframe>
Video Courtesy Sage Rose-Creative Commons International.
For Information on Head Lice treatment and Prevention See-Head Lice Prevention and Treatment-Courtesy CDC
Body Lice. The behavior of body lice or cooties is totally different than that of head lice. Females lay more eggs than head lice (up to 300 eggs) and the life cycle can be completed in a shorter time than head lice (in as little as 25 days). The eggs are deposited on clothing and the nymphs and adults remain on clothing even while feeding. Body lice infestations are not common in California, but typically develop when a large number of people live closely together under poor sanitary conditions (war time). One individual can harbor a large colony of this species. Over 30,000 body lice have been removed from a single individual. Even though such an infestation is rare, these insects have such a rapid reproductive capacity that huge numbers can develop rapidly unless control is quickly initiated. Close contact with someone who is heavily infested can result in a transfer of several hundred lice.
As in the other 2 species of lice that attack humans, body lice cause dermatitis and considerable irritation. Scratching can result in secondary infection and sometimes blood poisoning. In long term infestations, a condition called vagabond’s disease may develop. In this case, the victim’s skin becomes thickened and deeply pigmented. This condition is not due to a microorganism but is due to the victim’s skin reacting to the long term feeding of the lice. Finally, individuals who are heavily infested with lice may develop a systemic or overall body effect. The following is taken from a report made by a scientist who recorded his symptoms after allowing 700 to 800 lice to feed on him two times a day. "I started feeding twice a day and almost immediately a general tired feeling was noticed in the calf of my legs and along the shin bones, while on the soles of my feet and underneath my toes the tired feeling was so intense as to often prevent sleep until late in the night. An irritable and pessimistic state of mind developed. An illness resulted with symptoms very similar to grippe and a rash similar to German measles was present, particularly over the shoulders and abdomen. Once the experiment was discontinued the symptoms disappeared within a few days."
Vagabonds Disease. Image Courtesy Univar Corp.
Body lice are capable of vectoring diseases; the most important is epidemic typhus. Based on actual human deaths, this is one of the top three insect-vectored diseases in the world. The etiological agent is Rickettsia prowazeki and the primary vector is the body louse. Body lice are the main louse transmitters; head lice are less mobile and they don’t reach the high populations on the body louse—therefore they are less frequently passed from person to person. Epidemics usually occur in the winter when people are huddled closely together and the lice migrate nightly from one pile of clothing to the next.
The rickettsias multiply in the epithelial cells of the louse intestine and are voided with the feces. After feeding, body lice defecate next to the bite; subsequently, the rickettsia can be scratched into the bite by the host. In addition, after a period of time the feces dries and the rickettsia become airborne resulting in transmission through inhalation.
Historically, this disease has been instrumental in the outcome of several wars. In some cases, it has killed more soldiers than fighting. Epidemic typhus was a major factor in Napoleon's withdrawal from Russia. During World War I this disease killed over 3 million Russians. Typhus was again threatening in the early years of World War II. During 1942 there were 83,000 cases in North Africa. When allied forces landed in Italy in l943, a typhus epidemic was well underway in Naples, Italy. There was congestion, unsanitary conditions, food scarcity and malnutrition. The death rate was around 81%, and it was quite likely that the entire city would have been annihilated, if not for a very effective louse control program initiated by the allies. The program consisted of applying 10% DDT dust to the clothing of the majority of the city’s inhabitants. The people were lined up for blocks. The DDT was applied from a backpack duster with an attached elongated tube. The tube was inserted into the shirt and/or pants of the individual to be treated and then the duster was turned on—as a result the dust was blown throughout the clothing.
Epidemic typhus is characterized by severe headache, high fever and a rash caused by small hemorrhages. Today the disease is kept in check by vaccines, modern antibiotics, and the use of pesticides to prevent the buildup of louse populations. According to the CDC, a body lice infestation is treated by improving the personal hygiene of the infested person and assuring a regular (at least weekly) change of clean clothes. Clothing, bedding, and towels used by the infested person should be laundered using hot water (at least 130°F) and machine dried using the hot cycle. Sometimes, the infested person also is treated with a pediculicide, a medicine that can kill lice; however, a pediculicide generally is not necessary if hygiene is maintained and items are laundered appropriately at least once a week. A pediculicide should be applied exactly as directed on the bottle or by your physician.
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Chapter 6 Questions- True/False
42. Body lice mainly lay their eggs on body hairs and can cause a condition referred to as Vagabonds’ disease.
43. One symptom of crab lice is blue spots on the skin.
41. Crab louse, Pthirus pubis, also known as pubic lice, attack humans and a few species of gorillas.
44. If a child who hasn't reacjed puberty is attacked by crablice, they will typically be found along the elelashes.,
45. Female crab lice deposit their eggs on body hairs. A single female can deposit over 500 eggs.
46. Crab Lice are not proven to vector ant disease to humans.
47. Head lice are epidemic throughout the world with infestation more common in weomen than men.
48. Body lice deposit their eggs on clothing with over 300 lice reported from one individual.