Wood Destroying Beetles, Carpenter Ants and Siricid Wasps



Wood Beetles

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Category: 2, 7B

Areas of high humidity and warm to hot climates are highly susceptible to the damage from wood boring beetle. In the western United States, California, Oregon and Washington are susceptible to a greater level of wood boring beetle infestations than is currently documented. As a result, further emphasis should be placed on examination of crawl spaces in homes of western states. This is of special importance in those structures in close proximity to the ocean and frequently experience high in humidity. 

As the U. S. population increases, in combination with the need for lumber, there has been an increase in the use of salvaged, second growth, and imported timber. As a consequence, more problems have developed from wood destroying insects. Salvaged timber typically has more insect problems, fungal damage and other pest infestations. When this type of lumber is used in structures, new challenges to the pest control operator develop. 

Second, growth timber is a result of replanting deforested areas and typically results in lumber that is unusually palatable to these organisms partially, due to high starch content.  The heavy importation of timber and products such as antiques, bamboo furniture, cabinet facings and other items undoubtedly results in new and challenging species of wood destroying beetles. 

Wood boring beetles fall into 2 broad categories--those that reinvest wood and wood products and those that do not. Generally speaking, beetles that do not reinvest wood require bark to be present for egg deposition. Those that reinvest can lay their eggs on wood with or without bark.

The following insects are commonly referred to as false powder post beetles:

  1. Bostrichidae/Bostrichinae is false powderpost beetles, twig borers.

  2. Anobiidae are false powerpost beetles.

  3. Bostrichidae /Lyctinae are true powderpost beetles.


This is a fairly large group of beetles, comprising of approximately 70 U.S. species that range in size from 1/8 inch to over 2 inches in length. Most are black in color, cylindrical in shape and have short-clubbed antennae with 3 to 4 terminal segments. When viewed from a dorsal angle, the head is almost totally hidden by the hood-like prothorax. The head is also inserted into the thorax and only partially visible from any angle. Most species possess pyramid shaped spines on the top of the prothorax (behind the head). These beetles typically infest dead wood in nature and are not considered pests. However, there are a few species that is a stored product pest and a few that are wood pests.

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The lesser grain borer is a stored grain pest. Image courtesy of Clemson University-USDA.

Bostrichid beetles differ from the other 2 families of beetles that commonly reinfest wood by the fact that the adults bore into wood forming tunnels for egg deposition. The other families lay their egg externally on the wood. With bostrichids, oviposition (egg laying) occurs in the wood pores leading to these tunnels. Once hatched, the larvae bore throughout the wood, thus forming tunnels of varying size. The larval stage of these beetles is typically C-shaped with a well-developed head capsule and no thoracic legs. Also the thoracic area is somewhat swollen. Pupation occurs near the surface and emerging adults eat their way to the surface leaving circular holes in the wood. These beetles are most abundant in the tropics and typically are not as important (as a group) of wood pests as are the other 2 families in this category

Lead Cable Borer-Scobicia.
This species is endemic to North America and most common in the western states but undoubtedly has been shipped around the nation via transportation in wood and wood products. It is common along the Pacific Coast, particularly in Northern California and Southern Oregon.

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Lead cable borer. Forestry Images

Adult beetles are small, shiny black and about 0.2 inches in length. There are a few other species of beetles in the genus in the U.S. that are similar in appearance, including the red-shouldered shot hole borer: this shot hole borer is common in the eastern U.S and attacks hickory, persimmon, and many other deciduous hardwoods. Lead cable borers have the typical appearance of many bostricid beetles; adults are cylindrically shaped, black, short and have a head that hangs below the prothorax and is not visible from a dorsal angle. The front half of the prothorax is covered with shot sharp spines. The short antennae are capitate with a 3 serrate terminal segments. Damage from this species appears as narrow feeding channels that are tightly packed with stringy feces.

This is one of the more interesting of the bostrichid beetles. It normally infests dead and seasoned oak and less commonly attacks acacia, California laurel, eucalyptus, maple, and other hardwoods. Adult beetles commonly reinfest wood from which they emerge or other sources of nearby wood.  They are also attracted to cork in wine bottles. There is only 1 generation per year, and adults typically emerge in the summer months.

One of the more interesting facets of their biology is that this insect also bores into lead sheathing. Actually a number species of beetles and other insects bore into lead, but this is the more common and notorious of the lot. We are not sure why this occurs, but one author reports that the lead cable borer is greatly stimulated by heat. As a result, they are drawn to the heat absorbed by lead and even asphalt roofs. The main damage due to this activity occurs in the lead sheathing of telephone wires. The 2 mm diameter holes produced by this activity allow moisture to enter and short-circuit the lines. Another common name is the short circuit beetles. Periodic inspection of telephone lines is frequent, especially in those areas of the Pacific Northwest that receive heavy rainfall. .

This species typically exhibit a single generation annually, with larvae reaching full maturity to 9 months. The beetles have been known to cause severe damage to wine casks, hardwood paneling and floors, and sheetrock which they emerge through from the wall members within the wall voids. They appear to be attracted to freshly painted buildings.  

Wood and small wood products that are heavily infested with lead cable borers should be discarded. Valuable infested wood objects or those that are not removable may require fumigation or some alternative treatment that will penetrate wood to kill larvae and adult. Infested wood can be removed and replaced.

Bamboo Borer


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Bamboo borer. Image Public Domain.

This bostricide beetle is cylindrical, reddish-brown and approximately 1/8 inches in length. The anterior dorsal half of the prothorax bears concentric rows of stout spines. This beetle is endemic to Asia but has been shipped all over the world within its primary host bamboo. In parts of Asia, this beetle causes considerable damage to cut bamboo, one of the major materials used in home and furniture construction. It also is a stored product pest infesting drugs, grain, flour, and spices. Even though it has undoubtedly been shipped to the U.S. in bamboo furniture an undetectable number of times, it has not becomes well-established here and typically is not a major problem.

An additional problem with this insect in much of Asia is associated with the fine powdery frass that is expelled from the bamboo as the beetle larvae feed. The frass contains small bamboo fibers that are quite abrasive. Because bamboo is commonly used in roofing construction, these fibers filter down onto inhabitants and cause considerable itching. Considering the number of people living in Asia and the extent that bamboo is used in home construction, this may be one of the most common human maladies of the world. Actually on one of our trips Indonesia, I developed a rather sever rash on my legs. Upon a quick visit to a local hospital, I was told it was due to this very problem. It is amazing what you learn and experience in foreign exotic travel.

Black Polycaon-Polycaon stouti. This is a jet black cylindrically-shaped beetle that is ½ to 1 inch in length. Its shape is atypical for bostrichid beetles in that he head points forward and is not hooded by the prothorax As a result, the head is clearly visible when viewed from above.  In addition, its round prothorax is smooth as opposed to having many stout spines, as occurs in other bostricid beetles.



Adult of a black polycaon, an atypically appearing bostrichid. Image courtesy of Urban Entomology, Ebling.

This beetle occurs in the Pacific Coast States, British Columbia and Arizona. As with other types of wood infesting beetles, the black polycan has been transported to areas where it normally does not occur.  It readily attacks both hard and soft woods. As a pest, it is most commonly found attacking the 3-ply paneling used in making desks and other furniture. The larvae bore in the inner ply of soft wood and are not detected until the adults emerge eating their ways through the outer layer of hardwood. In doing so, they leave circular emergence holes that are approximately 7 mm in diameter. They do not reinfest finished wood, so in these cases initial infestations typically occurred prior to manufacturing the furniture. The entire life cycle takes about 1 year. Stacked plywood is also occasionally attacked. There are reports of this beetle exhibiting extended lengths of its normal 1 year life cycle. These include developmental period ranging for 8 to 22 years.

Horned Powder post Beetles - Heterobostrychus Sp. This is a genus of bostricihid beetles that are commonly named the horned powder post beetles. Like other beetles of this family, these live in wood, often inflicting significant damage on timber and other wood products. This genus can also be found in crop plants such as cassava, potato, coffee, oilseeds, and pulse crops.

Heterobostrychus aequalis, known commonly as the black borer, lesser auger beetle and kapok borer, is a notorious pest of many wood products. It has been found in plywood, furniture, wooden toys, wooden clogs, and carvings.

These beetles have been introduced to other areas on timber shipments and various wood products. Several species have easily established in new areas, particularly those with warm climates, as they do not tolerate cold. H. aequalis is now found on 6 continents in regions within 40° of the Equator. The lesser auger beetle is found in India, Asia, the Middle East and South Africa. Detections in the U.S. have been associated with imported timber. The damage caused by this beetle and other species in this genus occurs entirely below the surface; this damage is not usually discovered until the wood disintegrates. However, the presence of the tiny adult exit holes is useful for early detection. The lesser auger beetle usually infests unfinished floors, window sills and furniture. Bamboo is the most common host.

Spider Beetles.
The appearance of these beetles depends on the species.  Common species include the American spider beetle, brown spider beetle, hairy spider beetle, white marked spider beetle, and the Australian spider beetle. While all species are slightly different, they have many common characteristics.  Spider beetles are oval in shape, have a large globe-like abdomen, long legs, and a head that is usually not visible when viewed from above.  Spider beetles generally range in length from 1/16 to 3/16 inches, and most are brownish-black in color. The larvae are typically C-shaped, cream colored and have light brown heads. Tiny exit holes are produced by the adults when they emerge from wood tunnels leaving sawdust-like material on the surface.

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Spider Beetle.  Right Image Courtesy Gunther Tschuch. CC BY-SAS 3.0. Left Image Courtesy Sarefo  CC BY-SA 3.0.

These beetles used to be placed in the family Ptinidae but have subsequently been reclassified as a subfamily of Anobiidae. Although certain species of this subfamily are considered wood pests, most attack dried animal or plant matter. When found in structures, their larvae may be found in stored products such as flour, wool, and similar materials. Mature larvae may tunnel into wood to prepare for pupation. In the case of heavy infestation this damage can create problem in cabinets, shelf and other storage areas of homes. Since this beetle can continue to develop in their hosts, including production of new egg laying adult, they are capable of reinfesting wood.

Anobiidae. False Powder Post Beetles

Almost all anobiids are small measuring 5/16 inch or less in body length. Their shape is quite variable but can be distinguished from the bostrichids in that the head is not pulled into the thorax and is readily visible; but as with the bostrichids, their head cannot be viewed from a dorsal angle, as it is hooded by the thorax. Their antennal shape is quite variable but with most species that attack wood, the last 3 segments are elongated. As with the bostricids, the larval body is C-shaped, but unlike bostrichids, the larvae bear 3 well-developed thoracic legs.

Deathwatch Beetles. There are a number of species of deathwatch beetles around the world. They get their name from the method of attracting the opposite sex. When sexually mature, either sex will tap its head against any available surface. This makes a faint ticking sound (like a watch) which alerts and attracts the opposite sex. An old English superstition is that this faint ticking is a sign of impending death. This sound was most frequently heard in rooms where someone was very sick and consequently where little noise was made to drown out the ticking.

The California deathwatch beetle is the most common species along the Pacific Coast. The adults range in size from 2.5 to 5.5 mm in length; they have striated elytra and are humpback in appearance. This is the most destructive of the false powder post beetles in the U.S. As with other species of anobiids, it prefers old wood and does most of it damage in crawl spaces with high humidity.


Deathwatch Beetle. Image Courtesy Forestry Images. Pest and Disease Library.

This species is most commonly occurs along the western coast of North America where it mainly attacks barns, outbuildings, damp timber crawl spaces and barns. It infests a wide variety of hard and softwood but seem to prefer Douglas fir, the most common used structural timber. This species is very similar in appearance to the eastern deathwatch beetle except. The antennae are 11 segmented and the pronotum is distinctly narrower than the base of the elytra. Adults are light to dark brown and occasionally reddish brown. This species can be distinguished from most other anobiids in the Pacific Northwest by its pointed thoracic dorsum.

Adult beetle emerge primarily in the summer months, when females deposit up to 100 or more eggs in deep cracks in wood. Hatching larvae feed for 3 to 6 years within damp timber in crawl spaces and outhouses. Infestation can exist for over 30 years, before being discovered. Larvae of this species feed mainly in sapwood with a 13 to 16 % moisture content; they will consume heartwood, if the sapwood is depleted or if the heartwood has a moisture content of 17%. These beetles will readily reinfest and can reduce timber to a powdery mass. The beetles require 2 to 6 years to complete development. The larvae do not survive more than 18 months when wood moisture content is 10 to 11 % and survival drops even further at 19%. Levels above 19 % reportedly enhance the possibility of fungal growth which is detrimental to egg and larval survival. Lowering wood moisture content to 12% or lower will reduce the number of this species found in timber. Proper placement of vents or removal of vegetation that blocks vents to the outside will lower the degree of infestation of these beetles. In addition, a plastic vapor placed on the soil will lower wood moisture.

 In the U.S., this beetle is widely distributed, but it has not nearly reached the status of its importance in Europe and New Zealand. For example, in Germany and New Zealand, it is reported to infest nearly every building over 15 years or older. It attacks structural timber, paneling, flooring and furniture. In these areas, it is a major part of the structural pest control industry. Infestations appear to be closely dictated by environmental conditions, since moderate temperatures are essential for its development. The furniture beetle only attacks well-seasoned wood and will not attack wood where the bark is still present. According to one source, it is rare for soft woods to be attacked until about 20 years and sapwood of oak until about 60 years after it has been cut.

Eastern Deathwatch-Hemicoleus carinatuse.  This species is 1/6 to ¼ inches in length and reddish brown to dark brown with 10 segmented filiform antennae. As its name implies, it is widely distributed in eastern North America. It primarily attacks elm, maple, ash and beech lumber, especially if damp. Infestations are primarily found in window sills, flooring, joists and structural beams. It consumes both hard and soft woods. Reportedly, the damage to hardwood due to the presence of these beetles is similar to that of powderpost beetles, except the emergence holes are large and the frass is coarser.


Eastern deathwatch beetles. Image Courtesy entomart.

Furniture Beetles. Anobium punctatum. This reddish brown beetle is 1/6 to 14 inches in length and bears longitudinal row of punctuations on the elytra. The terminal 3 antennal segments are swollen and elongated and longer than the combined first 8 segments. The gray to white larvae bear double rows of spines on the dorsum.  This species is a common pest in England and the U.S. Reportedly, 2,000 U.S. homes built since the 1970s were randomly surveyed for this pest and none were found. In this case, it was thought that the change in heating and ventilation contribute to the lack of these homes.

Adults typically emerge in the spring with female shortly laying 20 t0 60 eggs in bare wood or holes in finished wood. There is a reported preference for females to oviposite on rough surfaces.  Humidity below 60% impaired egg hatching. Full larval development typically requires about 1 year but may be delayed up top 6 year under unfavorable conditions. Pupation occurs close to the surface and lasts approximately 3 weeks. During mating, males and females return to their emergence hole. Once completed, the males return to the wood surface.

Anobium punctatum

Furniture beetle. Image Courtesy of entomart. 

Lyctinae -Powder Post Beetles

For years this group of wood boring beetles was placed in a family of its own, namely the Lyctidae. However, it now occurs as a subfamily (Lyctinae) in the Bostrichidae.  Powderpost beetles are relatively small (3 to 7 mm in length), dark brown to reddish-brown and possess elongated bodies. These beetles can readily be distinguished from the other families of beetles that reinfest wood by the presence of a 2-segmented antennal club. Powderpost beetle adults are small, ranging in size from 1/8 to ¼ inches in length. They are elongated, parallel sided and somewhat flattened. They are referred to as powderpost beetle because the produce a powdery, talc-like frass lacks pellets or grains. In the United States, true powderpost beetles are second to only termite in terms of causing damage to lumber and other wood products.

As with the other families of beetles that reinfest wood, lyctid larvae are C-shaped; however, unlike bostrichids and like anobiids, they possess well-developed legs. However, the latter 2 can be separated by the fact that the legs of anobiid larvae have 3-segments and no terminal claw, while those of a lyctid are 5-segmented with a terminal claw. An additional characteristic that can be used to distinguish powderpost beetles from other wood infesting beetles is that their last abdominal spiracle is approximately 6 times as larger than others.


Left. True Powder Post Beetle Belonging to the Genus Lyctus. Image courtesy of USDA Forest Service. Right. Larval stage of a true powder post beetles. Image courtesy of USDA Forest Service.

The larvae and adults of true powderpost beetle are not frequently available when inspecting an infestation. There are a few characteristics that can be of use in distinguishing the 4 types of wood boring beetle that reinfest. With true powderpost beetles, the powdery frass is loosely packed in round galleries and adult exit holes are 1/32 to 1/4 inches in diameter, In the case of anobiid beetles, the frass contains many round to oval pellets that are stuck together in clumps and are loosely packed in round galleries that measure 1/16 to 1/4 inches in diameter. On the other hand, in the case of other bostrichid beetle, the frass consists of fine to coarse powder with few to no pellets and is found in variable galleries that measure 1/4 to 3/8 inches in diameter.  Finally, with the old house borer there are round galleries with evident ridged marks that contain tightly packed coarse powder and pellets. The oval diameter of the exit holes measures 1/4 to 3/4 inches in diameter or better.

In the U.S., there are 10 species of true powder post beetles, and 6 of which are of economic concern. In the continental U.S., these pests are second only to the termites as far as insect destruction of lumbered wood but confine their damage to large pored hardwoods, such as oak, hickory, ash, and bamboo. These beetles attack any product made of these woods including hardwood flooring, furniture, toys, statues, gunstocks, axe handles, and similar objects. These beetles can readily be distinguished from the other 2 families of beetles that reinfest wood by the presence of a 2-segmented club forming the tip of the antennae. Unfortunately, signs of their damages are not visible until the adults emerge.

This type of information may also be use in identifying infestations of wood boring beetle that do not reinfest. In the case of adult longhorned beetles and round headed borers, the larval galleries are rounded and contain little, if any coarse to fibrous frass. The emergence holes are also rounded and measures 1/4th inches in diameter or larger. With metallic wood boring beetles, adults and flat headed borers, the oval galleries contain sawdust-like frass that is tightly packed. With ambrosia beetles, the round galleries are stained blue to black by fungus and contain no frass. Finally with scolytid beetles, the round galleries fan out in a definite pattern from a central tunnel. The frass is bark-colored and tightly packed.

As far as pest to wood and wood products, the 2 most significant species are Lyctus planicollus and Trogoxy parallelopipidum. Due to increased international trade, new exotic species of these beetles are frequently introduced in to the U.S. and other areas of the world.

Adults of powderpost beetles are nocturnal and fly to lights, a behavior that may be useful in detecting an infestation. Dead or living adults are frequently found on or near windows, when infestations occur indoors. Their eggs are deposited in the pores of hardwood, which are exposed when the wood is cut, or the female may open them herself. Finely sanded, painted, varnished, or other finished wood is not normally suited for egg laying. Upon hatching, the young larvae tunnel with the grain but eventual can take an irregular course. As they feed, they pack their tunnels with the very fine powdery frass.

The entire life cycle of powderpost beetles from deposition of the egg until emergence of the adult may be completed in as little as 6 months or less and may be extended to years under unfavorable conditions. Adults are most active in warn situations. Of course with modern heating system, their activity can occur year around. They typically begin to deposit their eggs soon after emergence and mating. Adults commonly hide in crack and crevices during the day and can spend several hours on wood during the night. The female deposits single eggs and can produce up to approximately 50 in her 2 week existence. The eggs hatch in approximately 8 day and the developing larvae range in development to maturity from 2 to 9 months, depending on temperature, moisture content and nutritional status of the host.  Trogoxy parallelopipidum, one of the more destructive and widespread species in the U.S., can complete devlepoment in as little as 2 months under ideal conditions. Once the larvae are ready to pupate, they typically bore close (1/4 inch) to the wood surface to form the pupal chamber.

Three factors primarily determine the attractiveness of hardwood to the attack of these beetles, namely pore size and starch and moisture content. The primary nutrient of wood to lyctids is starch, since they do not digest cellulose and other wood components. The starch content in lumber depends on the species of tree, season when the tree was cut and method by which it was dried. Since starch is lost with aging. Lyctids attack new lumber as opposed to old. Lucid larvae can feed in wood with water content between 8% and 32%. Larval development of these beetles typically occurs in lumber with moisture content between 8 and 32 %, with optimum activity occurring between 10 and 20 %. Green lumber contains around 50% water and is not accessible to attack by these beetles. Finally, hardwood with large pores is preferred, as wood with fine pores is not readily accessible for powderpost beetle depositing eggs. Reportedly, this is associated with the correlation of the size female’s ovipositor and the size of the pores. They also typically only attack the sapwood of hardwood, as it is generally higher in soluble nitrogen and amino acid content than is heartwood. Oak, ash and pecan all have large pores and are frequently infested with these beetles

In nature, these beetles normally attack the branches and trunks of dead and dying trees. Since these are such small beetles and probably don’t fly that far from these natural sources of food, infestations in buildings, homes, furniture and other wooden products generally begin by infested wood being built into or brought into the structure or from nearby infested old wood. In many cases, this may begin at the lumberyard or manufacturing location. Based on this, sanitation becomes a very important, if not the most important factor in preventing infestations. Since most of these beetles have a relatively long life cycle, the periodic elimination of susceptible scrap or excess wood is essential and quite effective.

At manufacturing locations or lumber yards where is wood stored for any length of time, periodic inspections are essential, especially since visible signs of damage are not detectable for months or more following an initial infestation. Unused firewood or stored old lumber can lead to infestations in homes.

These beetles are typically not capable of infesting lumber that is finished with varnish, paint or even fine sanding in some cases. Such finishes should also include the end cuts. Once an infestation is established in a structure or other object, possible controls include the use of heat, fumigants, and even toxic solutions in some cases.

Beetles that Do Not Reinfest.

Beetles that typically require bark to be present for egg laying and do not reinfest in lumber are:

  1. Buprestidae (metallic wood boring beetles or flat headed borers)

  2. Cerambycidae (longhorned beetles or round-headed borers)

  3. Scolytinae (bark beetles)

  4. Scolytinae – Platypodinae (Ambrosia beetle)

Buprestidae-Flat Headed Borers. Adults of this family can readily be recognized by their flattened and boat-shaped bodies and the fact that there is metallic coloration somewhere on the body. The shape of the larvae is very distinctive with a broadened and flattened thoracic area and no legs.


Adult metallic wood boring beetle. Note the characteristic shape and metallic coloration. Images courtesy of fir0002 | flagstaffotos.com.au  GFDL 1.2.

As previously indicated, these beetles almost always (there are rare exceptions) require bark to be present for egg deposition. In rare instances, they can deposit their eggs on fire scared or freshly cut lumber or even more rarely old lumber. The larvae bore throughout the tree or in some species beneath the bark. These beetles normally attack trees that are either cut, disease, damaged by fire or in some other way have lost their vigor. Healthy trees have copious amounts of sap that serve as defensive mechanism against beetle attack. In healthy trees, sap tends to drown out hatching larvae. As a consequence, wood boring beetles rarely deposit their eggs on the bark of healthy trees. However, when a tree is stressed, its sap flow drops and beetles and other wood boring insects are readily attracted. Hatching larvae mine heartwood as well as sapwood. Their mines tend to be flattened taking on the shape of the enlarged larval thoracic area and are tightly packed with powdery frass, a characteristics which can be used to distinguish them from the mines of round headed borers. The mines of round-headed borers are circular in shape and are loosely filled with a mixture of fibrous and powdery material.

The life cycle of metallic wood-boring beetles is quite long requiring 1 to 3 years to complete development. However, if an infested tree is lumbered, the cycle of any surviving larvae in the wood can be greatly extended. Lumber contains less moisture and nutrients than living or freshly cut trees. In extreme cases, this cycle may be extended to 20 or more years.

On occasion, adult buprestids do emerge from the walls and other wooden structures in homes. Invariably, these are surviving larvae that have completed their development and “were built into the house.” This is fairly rare because most lumber is kiln dried, and any infesting larvae cannot survive this process.

Golden Buprestid-Buprestis aurulentis


Golden buprestid. Image Courtesy whatsthatbug.com CC BY-SA 3.0

The golden buprestid is of special concern in the Pacific Northwest. This beetle is most frequently found attacking Douglas fir but is also attracted to pines, spruce and occasionally western red cedar. Females typically deposit their eggs on the bark of trees that have been weakened or dying from fire, struck by lightning, disease, and drought or recently cut. On occasion, they oviposit on wood or trees that lack bark. The can deposit on fire scars, cracks in freshly cut lumber and exposed wood in new houses.

The mature larvae of this beetle are legless, approximately 1` ¼ inches in length and lack eyes. As with most buprestid larvae, the prothorax is flattened and consequently, as the larvae bores through wood, they leave flatten (broadly-oval) tunnels that contain powdery frass. The adults are approximately ¾ inches in length, boat-shaped, somewhat flattened and a golden green with bronze coloration along the dorsal margins and where the elytra meet in a straight line down the back.

The life cycle of this species is quite long, sometime requiring several years to complete. This length of development can be greatly extended once a tree is cut and lumbered. There are reports of adults emerging from the wall of houses 30, 40, or even 50 years. They do not reinfest or attack kiln dried wood.

Goldspotted Oak Borer. This is a species of flat headed borers known by the common name goldspotted oak borer. The larvae are wood boring beetles that are currently destroying stands of oak trees in the Cleveland National Forest in California. It is now considered of concern in many states including New York. 

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Gold spotted oak tree borer. Courtesy Mike Lewis - Template:Cisr.ucr.edu CC BY-SA 3.0

The initial destruction in oak in the stated area was first discovered in 2002 near Descanso, California. It was initially thought that this damage was due to drought, since there was damage in healthy trees. Generally beetles within this family do not readily attack healthy trees. On further investigation, it was determined that the damage was Agrilus coxalis, a species that was not previously established in the area. The most common species of trees attacked by this beetle are the California black oak and the coast live oak.  However, to a lesser extent canyon live oak and silverleaf oak are also attacked. This pest was initially found in the region in 2004 at Cuyamaca Rancho State Park.  In 2008, this beetle was confirmed as the cause of oak damage after larvae and adults were collected from the host trees.

To date very little is known about the biology of this species, including if it was introduced into the area or became established as part of a natural range expansion. The beetle has been found in Mexico, Arizona and Guatemala, but in these areas, it is not considered a pest of these trees. However, it is currently thought that the borer in Arizona is a distinct species from the one in Central America (Agrilus auroguttatus).

Reportedly damage in trees near the Descanso area was found on 67% of oaks examined, and of these 13% of the trees were dead. The affected region is an area 50 by 40 kilometers, mostly within National Forest boundaries in the Peninsular Ranges east of San Diego. Damage from the feeding of the larvae of this beetle is characterized by blackened feeding galleries, thinning grayish crowns on injured trees, black and red staining on the bark as a result of sap draining from damaged phloem and dead twigs and branches. Emerging adult beetles leave D-shaped holes on the outside of the bark.

Initially, it was estimated that approximately 15,000 trees were killed by this wood boring beetle. However, on 9/3/11, the San Diego Union Tribune published a correction by UC Riverside researchers that upped the estimate at around at 80,000 trees killed. Of course dead or dying trees increase the possibility and resultant severity of wildfire in this already highly fire-prone area.

Adult beetle golden oak borers are dark metallic green with 3 characteristic yellow spots on each forewing. They are small, somewhat flattened and about ¼ inch in length.  The larvae are white to cream colored, legless and with a well-developed head capsule. They are somewhat flattened and have a distinctly wider thoracic area as compared to the abdomen.  They grow to about 2/3 inch in length before pupation.

Current research centers around finding a predator or parasitoid (preferably host specific) that preys on the beetle larvae. The U.S. Forest Service advises forestry workers to use current containment practices for the control of similar buprestid pests, such as the bronze birch borer and emerald ash borer. It has been suggested that if the beetles were introduced to the area, it likely would have been via firewood.  As a precaution, it is suggested to avoid transporting oak wood since it may spread the pest.

Longhorned Beetles-Round Headed Borers. Cerambycidae. These beetles are also referred to as the longhorned beetles. As their name implies, most but not all adults have elongated antennae. In some species, the antennae can be as long as or longer than the entire length of the body. Most have an elongated cylindrical shaped body and are further characterized by the fact that the first antennal segment (where it attaches to the body) is at least 5 times longer than the second.

A species of longhorned beetle. Image Courtesy of Brisbane Insects-Peter Chew.

The larval stage is a legless, club-shaped grub. The term round headed borer refers to the cylindrical tunnel this larva leaves as it bores through wood. As with the metallic wood boring beetles, these beetles rarely reinfest and typically require bark for oviposition. Their life cycle is very similar to that of the metallic wood boring beetles and can require several years to complete development in cut timber or stress trees. Again, the cycle may be greatly extended once infested trees are lumbered.


Club-shaped legless grub of a longhorned beetle. Image Dr. Kaae

New House Borer. One of the more common longhorned beetles that are found completing their development in lumber from infested trees is the new house borer. This species is prevalent throughout most of the western U.S. and western Canada. It attacks pine and Douglas fir, especially in fire swept areas. When lumber from such trees is built into homes, the emergence holes of the adults may be found in hardwood flooring, linoleum, plaster, plasterboard or any other covering of the infested framing of the home. Although the entire life cycle of these beetles is around 2 years, the emergence of the adult beetles typically occurs within the first year of building. This beetle is a native insect in western North America.


New house borer. Image courtesy UGA. Public Domain.

The common name of this beetle is a possible cause of confusion with the unrelated “Old” house borer that is found in the eastern U.S. The “New” house borer is a western species found from Canada south to California and most western states, and it feeds only on dead or dying trees. However, because lumbering practices often salvage trees recently killed by fire or bark beetles, the new house borer may be present in lumber used in construction. Females deposit eggs only on the bark of a standing tree or a log, and do not reinfest structures once they have emerged. It takes 2 years for the larva to complete its growth in the wood, but once the wood dries, the larva cannot survive. Only those larvae that are nearly full grown and can pupate, will survive in the milled lumber, and thus will emerge within a few months to a year after the wood is used in a new structure. The beetles infest only conifers, but the adults will bore through any other materials over the infested wood in order to emerge, including sheetrock, paneling, hardwood flooring, or linoleum.

The adult beetles are approximately 1 inch in length and dull dark brown to dark gray coloration. The elytra are relatively narrow with parallel sides, and the prothorax is short and rounded. Several raised ridges run the full length of the elytra. The filiform antennae are quite long and in males are about 2/3 the length of the body.

Characteristics Important to Control. The best control is to allow the infestation to run its course and then to repair any holes made by the adult beetles. If a heavy infestation is causing unreasonable damage, fumigation of the structure may be necessary.  In recent years, infestations by these beetles and others that do not reinfest are on an increase. The apparent reason for this is that lumber costs are increasing and therefore the use of lesser grades in home construction is correspondingly on an increase. In the past, fire damage trees (attractive to these beetles) were generally rejected for the production of lumber.

This species is endemic to North Africa. It was first discovered in North America in 1875 and currently occurs from Maine south to Florida and west to Michigan and Texas. There are records of its presence in California, but established populations of this beetle have not been recorded in the western states. It has been spread around the world in timber and wood products, and as a result, the beetle is now practically cosmopolitan distribution, including Southern Africa, Asia, the Americas, Australia, and much of Europe and the Mediterranean. It is also is known by several common names, including house longhorn beetle, old house borer, and European house borer.  

Old House Borer. Adults of the old house borer are 1 inch in length, slightly flattened and black to brown with elongate 11 segmented filiform antennae. The prothorax is round and characteristically bears 2 distinct bumps on top of the prothorax. The elytra may be nearly black or with grey to white patches that form 1 or 2 transverse bands. Then abdomen of females may extend slightly past the elytra, when viewed from a dorsal angle. Last instar larvae are club-shaped, cylindrical with dark brown mandibles. Three distinct dark simple eyes (ocelli) are prominent on each side of the larval head. The larval body taper posteriorly. The larval frass consists of somewhat granular, barrel shaped pellets measuring 1/24 inches. Irregular shaped wood particles which are not consumes are mixed with the pellets. The larvae tunnel with the grain of the wood and large galleries may be produced in areas that are favorable to larval development. Reportedly the cellulose component of wood is digested by these larvae.

https://upload.wikimedia.org/wikipedia/commons/thumb/e/ec/Hylotrupes_bajulus_%28huisboktor%29_%284%29.jpg/1280px-Hylotrupes_bajulus_%28huisboktor%29_%284%29.jpgCSIRO ScienceImage 1742 The European house borer.jpg

Larva and adults of old house borer. Left Image Courtesy Rasbak CC BY-SA 3.0. Middle Image Courtesy Siga CC BY-SA 3.0.  Right Image Courtesy CSIRO CC BY-SA 3.0

This species spend 2 to 10 year in the larval stage. Development of this species depends on prevailing temperatures, relative humidity and the moisture component of wood. Larval development occur most rapidly at temperature from 68 to 88 F, relative humidity between 80 to 90% , wood moisture content no less than 10%  and wood with a high nutrient content. Under optimum conditions, the larvae are capable of reaching maturity in approximately 2 years, such as in modern log homes that are less than 5 year old. However, normal larval development typically occurs in 3 to 6 years. In severe environmental conditions (low temperature and humidity), this developmental period can extent to 10 or more years. Unlike what its common name implies, this species is most commonly found in homes less than 10 years old. As the nutrient content of wood decreases with age, the larva has to consume larger amounts of wood. In Australia, the infestation of home construction is mainly caused by the use of wood already infected with the eggs or larvae of the beetles. This typically only occurs if the wood is not properly kiln-dried in production.  On the other hand, reports indicate that beetles found in homes are more than likely a result of an infestation originating in lumber yards.

The moisture content of structural indoor timber fluctuates during the spring, summer, fall and winter.  It follows that the life cycle of this beetle is closely associated with the moisture content of wood. As an example, the adult emerge and lays their eggs when moisture content of wood is on the increase in June and July. The larvae penetrate wood and begin feeding when moister is at its peak in late summer. The life cycle from egg to egg typically takes 2 to 10 years, depending on the type of wood, its age, quality, moisture content, and environmental conditions such as temperature. Only the larvae feed on the wood. Larvae typically pupate just beneath the wood surface, and the adults subsequently emerge in mid- to late summer. Once the exoskeleton of the newly emerged adult beetle has hardened, the adults cut oval exit holes (¼ to 3/8 inches), typically leaving coarse, powdery frass in the vicinity of the hole. Adults are most active during the day as temperatures increase in the summer. The female deposits an average of 165 day during their life. These eggs are deposit around 6 batches in unpainted cracks and crevices or between 2 layers of wood. Under optimum environmental condition, females live approximately 10 day and males 16. The eggs hatch in several days. As the larvae become larger by fall, their chewing can actually be heard from a distance of several feet. At the end of the fall, the moisture content of wood begins to decrease, as does larval feeding. In the winter when moisture content declines to a certain level, larvae cease to feed.

Several factors can be used to detect the presence of an old house borer infestation. Three to 4 year old larvae that are approximately 1 inch long can easily be heard feeding from several feet away. During the spring and summer when the wood content is high, the larvae are active.  However, during the winter when the wood moisture content drops below 10%, the larvae cease feeding. The age of the wood is important in detecting the presence of infestations of this pest. Old house borers generally infest houses that are less than 10 years. Wood older than 10 years may be infested, but larval feeding is greatly reduced and correspondingly, the larval growth can be greatly prolonged. Adult emergence holes are an indication that an infestation was or is infested. It is difficult to tell the difference between old or new exit holes. The presence of pale colored frass is a possible indication of a current infestation.

Eucalyptus Borer. The eucalyptus longhorn borer, Phoracantha semipunctata, is a serious and destructive beetle pest of eucalyptus trees. Native to Australia, it has spread to eucalyptus cultivation areas on all continents. Until recently, California's eucalyptus trees were considered virtually pest free. However, in 1984, the first North American record of this beetle was detected in dying eucalyptus trees in Orange County. Since then, this pest has been detected in almost all southern California counties and is expected to occur wherever eucalyptus is grown.

Adult beetles are approximately 1 inch in length and black and brown in color. The larvae feed beneath the bark of eucalyptus trees, creating sawdust filled tunnel. Upon inspection, circular exit holes 1/2 to 3/4 inches in diameter are readily visible. Lines of sap on the trunk may originate from these holes. Saplings may die within the first year after infestation. This is due to trunk girdling and mature trees may die within 2 years of infestation. The movement of infested eucalyptus firewood spreads these beetles. Adult are strong fliers and may fly several miles from their emergence site to find suitable egg deposition locations.


Adult eucalyptus borer. Image Dr. Kaae

As far as is currently known, all eucalyptus species grown in California are susceptible. Previous research suggested that only stressed trees were attacked, but recent studies indicate that even healthy trees can become infested. They attack freshly cut or fallen eucalyptus logs and branches as well as living trees.

There is no fail-safe method to prevent attack from these beetles. The best approach is to maintain trees in a vigorous condition and prevent dry season water stress with periodic deep irrigation. Eucalyptus firewood should be tightly covered with a tarp or plastic sheet for at least 6 months after cutting. This will prevent escape of emerging adults, which could attack surrounding trees and will prevent egg deposition by free flying adults. Pruning branches and cutting firewood during winter and early spring when adults are not active also reduces the chances of spreading this pest.

Through a cooperative effort of the University of California, Riverside and Santa Barbara County, 2 nursery sites for the establishment of a non-native wasp parasite of the eucalyptus longhorn borer are being maintained in Goleta. These nursery sites are used to raise wasps for distribution to other infested sites. At this time, the distribution of these wasps is determined by staff. Hopefully, the wasp will establish itself and not require further human assistance. Entomologists are optimistic regarding the potential success of this project.  

Although field trials have not been conducted, chemical controls are not expected to be effective against eucalyptus longhorn borer; the larvae feed inside the tree where it is protected from contact with control materials. Results of research trials using injected pesticides for control of similar wood boring pests on other trees have been discouraging. There are no pesticides currently registered for trunk injection in eucalyptus trees. Contact and/or residual activity pesticides are not likely to be effective in controlling this beetle.

Asian Longhorn Beetle.  Another beetle that attacks and is capable of killing living trees is the Asian longhorn beetle. This species is indigenous to Japan, Korea, and China. In 1996, it was found killing trees in a few areas of New York. At that time, federal agencies quickly attempted to eradicate it by killing and destroying all infested trees. A few years later, it was discovered in 3 communities in the Chicago area. As a result, new regulations have been implemented limiting the importation of solid wood packing materials from China. 

This is a potentially serious pest to our shade and forest trees, and anyone working in the pest control industry throughout the U.S. should be aware of its existence and report any findings immediately to the USDA-APHIS authorities. The adults are approximately 1.25 inches in length and the antennae are 1.3 to 2.5 times longer than the body (males have longer antennae than the females). Additional characteristics include:

  1. a shiny black body with about 29 white spots;

  2. antennae with alternating bands of black and white;

  3. legs that are bluish-white on the upper surface. 


Asian longhorn beetle. Image courtesy of USDA-APHIS.

The infestation in New York was most serious in maple and horse chestnut. Other trees infested and killed in the U.S. include poplar, ash, willow, elm, mulberry and black locust. Infestations start with the female chewing a funnel shaped hole in the bark and depositing a single egg in this depression. Hatching larvae subsequently feed under the bark and potentially girdling and kill the tree. Healthy trees are susceptible to the attack of this pest.

Wharf Borers. This beetle belongs to the family Oedemeridae or false blister beetles. This family is similar in appearance to the long horned beetles but is easily distinguished by the prothorax that narrows posteriorly behind the midline. They are also commonly referred to as the false blister beetles. This comes from the fact that when adults are crushed or otherwise harmed, they release a blistering chemical called cantharadin. These beetles occur in all U.S. states with the exception of Florida. Under optimum conditions, their life cycles can be completes in approximately 1 year (egg to an adult). The name wharf borer refers to the fact that the larval stage of these  beetles are typically found boring into pilings and timbers of wharves, especially along coastal areas. The adults are characterized via a black band across the end of both elytra. In addition, this beetle can be distinguished from other species of this family by the presence of 1 spur on the tibia of the forelegs and the distance between the eyes. In this case, this distance is 2 time the length of either eye. These beetles are similar in appearance to the longhorned beetles but can be distinguished to the latter by the shape of the prothorax. In the firmer the prothorax narrow posteriorly, as seen below.

Beetle May 2009-5.jpg

Wharf borer. Image Courtesy Alvesgaspar CC BY-SA 3.0

Eggs are deposited on fungal infested rotting wood; larvae hatch and burrow into and feed on rotten wood. Adults do not feed and are short lived. These are significant pests because they damage wood used in building infrastructures. Adults are approximately 0.4 cm in length and bear an orange prothorax and brownish elytra. They have elongate, cylindrical, slender bodies and filiform antennae that are half the length of the body.

This species is cosmopolitan or worldwide in distribution. They potentially can be found in any temperate situation where there is moist and decaying wood, such as wharf timbers that are alternately submerged by a tidal flow. Their distribution includes Australia, Denmark New Zealand, Japan, France, and Canada, England, Wales, and Scotland. This species is thought to be endemic to the Great Lakes region of North America; reportedly it has caused considerable damage to dock timber in this region; however there is still uncertainty in the scientific literature about the origin of this species.

Wharf borer adults are strong fliers and readily attracted to lights; as a result, adults may be present in different types of habitats Adults are commonly found on flowers and foliage, under driftwood and in moist rotten logs; larvae are almost always found in damp, rotting wood. Buried wood may harbor the larvae. Reportedly, there was an increase in numbers of this insect in London after WWII. Masses of timber were buried via bomb blasts. These were infesting the floors of gasoline stations, apartments, and even telegraph poles. Infestations are commonly found in wood that is intermittently submerged in fresh or salt water.

As with all beetles, this species borer has complete metamorphosis.  Depending on location and prevailing temperature, adults tend to emerge from June to late August. Eggs subsequently hatch in 5 to 11 days. First instar larvae subsequently burrow about 1/3 inches below the surface where fungal soft-rot is evident. The larval completes its development in 2 months to 2 years, again depending on prevailing conditions. The larvae produce celluase; this enables them to feed the cellulose and hemicelluloses components of the wood. Tunnels formed by these tiny larvae can be 10 inches in length. The cream white pupae complete development in 6 to 17 days, the exact length is influenced by temperature and relative humidity. Adults live for about 2 to 10 days under laboratory conditions. Wharf borers are known to infest both hardwood and softwood.

This species is typically of minor importance but should still be closely monitored for potentially infestations and damage to pilings, wharfs and other structural wood, especial in coastal areas. Often hundreds or thousands of adults appear in basements or low levels of buildings creating a significant nuisance problem. Even though these beetles are attracted to old building or wood, infestations in new building are not unusual.  Such condition likely result of the newer building being constructed on buried wood. Wood wetted by dog urine is attractive to these beetles.

Telephone Pole Beetle-Micromalthus dibilis

The telephone-pole beetle (Micromalthus debilis) is endemic to the eastern U. S. and possibly Belize.  Micromalthus debilis is the only living species of the nearly extinct family Micromalthidae; as a result, it can be considered a living fossil. Classification of this species is historically controversial and unsettled. This beetle has been widely disperse via commerce and currently has been recorded Hong Cong, Cuba, Brazil, New Mexico, British Columbia, Hawaii, South Africa, Lebanon and Mexico.


Telephone pole beetle. Image courtesy David Maddison CC BY-SA 3.0.

The tiny beetle is elongate and  approximately 1/16 inches in length and ranges from  dark brown to blue to blackish color, with brownish-yellow legs and antennae. The head and combined elytra are wider than the prothorax; they have large eyes protruding from the sides of the head.

This beetle is also referred to as vault beetles, due to the fact that they are occasionally found in large numbers in bank vaults. The larvae are wood-borers that in nature feed on moist and decaying chestnut and oak logs. It is no coincidence that the steel of many bank vaults are built over chestnut or oak panels and over time water from the panel condense resulting in partial decay-all the requisites for beetle development. Telephone pole beetles have also been reported as causing damage to buildings and poles. It is very difficult to control these beetle once inside a vault, since the infestation cannot be accessed. A vacuum can be used to remove emerging beetles. One approach has been to drill holes at the bases of the wood panels, thus allowing the condensed water to drain out.  In some cases, this has produces gallons of water. Once completed, a dehydrator can be used to further remove the moisture from the panels. In extreme cases, the panels may need t be removed.

Males of this species have not been found and the females reproduce parthenogenitically (reproduction without mating and females producing females). Even more unusual is that they also exhibit paedogenic development, meaning mature larvae are capable of laying eggs and producing other larvae.  The entire lifecycle is typically completed in 1 to 3 years. This of length of development is also somewhat unusual. Typically large beetles require this length to completed development (rhinoceros beetles, Macrodintia sp). Adult emergence typically occurs in the summer and is synchronous-all emerging at one time.

Reports of the species are infrequent and it is unknown whether they are rare, or common and unrecognized. A recent study found telephone-pole beetles in a survey of the indoor arthropod fauna in 50 houses located in and around Raleigh, North Carolina.

Scolytidae (Bark Beetles and Ambrosia Beetles.  Bark beetles and ambrosia beetle were once placed in separate families namely Scolytidae and Platypodidiae. These are now subfamilies of the Curculionidae or weevils. These are relatively small (3 to 5 mm length), cylindrical, robust beetles with a head that is partially or completely concealed when viewed from above. Their antennae are short with a 3 to 4 segmented terminal club that can be compacted in a tight ball.


Typical scolytid or bark beetles. Right Image Courtesy Dr Kaae.

Bark beetles are one of the most important, if not the most important, of our forest pests. Huge numbers of these beetles are attracted to trees that are weakened by drought, forest fires, and disease or merely by lack of sufficient light (under-story trees). In these conditions, or even if a tree is merely cut, its natural defense of sap flow is greatly reduced. Trees in this condition release chemical odors that attract these beetles. Once a beetle is attracted to a tree and begins to feed, it releases an aggregation pheromone that is produced in its gut. This chemical attracts other individuals of the same species which in turn release more pheromone and in time thousands of beetles are attracted to the weakened tree. This mass attack eventually kills the tree. This is a very effective means of finding susceptible trees. Healthy trees do not release chemical odors that are attractive to these beetles and even if a beetle were to fly to and attack a healthy tree, it would be drowned by the sap flow prior to releasing the aggregation pheromone. The elm bark beetle is also a key vector of Dutch elm disease, a fungal disease that has killed many of the American elm trees in the U.S.

Bark beetle only attack trees with bark and that have enough moisture content to sustain their survival. They larvae are capable of surviving in wood that has not has all its bark removed.  They may continue to feed in these infested pieces that are built in structures and can be of considerable concern to homeowners once they emerge on structures. Chemical control is not needed at this point since it is a temporary situation and these beetles cannot reinfest. The 3 most common genera of bark beetles are Dendroctonus, Ips and Scolytus

Once male and female beetles reach a susceptible tree, they bore into the bark and form an elongated brood gallery between the inner layer of the bark and the sapwood (outer surface of tree just under the bark). Depending on the species, this gallery may be occupied by an adult male or female or in some species the male may have a harem of two to four females. After mating, a female deposits her eggs on both sides and at short even intervals along the elongated brood gallery or chamber. Once the larvae hatch, they bore out from the brood gallery at a more or less right angle remaining between the bark and sapwood. Each species make characteristic engraving patterns in this area. The width of the larval galleries increases as the larvae grow and continue to feed. These tunnels are frequently packed with their frass. Immediately prior to pupation, the larvae form a pupation chambers at the end of their tunnel. Once the adults emerge from the pupae, they eat their way to the outside through the bark leaving small circular emergence holes. In heavy infestation, it almost looks like someone shot the tree with buckshot; hence another common name for these beetles is shot hole borers.


Bark beetle gallery. Image Courtesy L. Shyamal - CC BY-SA 3.0

Since these beetles cannot survive in seasoned wood or even in trees that have been cut for a year or more, they are not a structural pest.  However the pest control operator should be aware of their existence, since the building of expensive-trendy log cabins is coming very popular, especially in mountainous areas. It is very unlikely that these beetles would attack such an existing structure, but built-in beetle infestations may cause some nuisance problems.

Ambrosia Beetles. As with bark beetles, ambrosia beetles typically do not reinfest, but unlike the bark beetles, they bore into and form galleries that extend several inches deep into weakened trees.  These tunnels may be used for several generations provided sufficient moisture is present. Ambrosia beetles do not feed on wood but feed on fungi that grow on the walls of their tunnels. These beetles are often referred to as wood stainers, as the tunnel walls take on a black or brown color due to the fungi.

These beetles do not reinfest and cannot survive in seasoned wood and therefore are not a structural pest.  However, since their galleries do extent deep into trees, it is not uncommon to find seasoned wood or wood products that contain damage due to previous infestations.  In this case, all damage was done prior to the production of the lumber or manufacturing of the product. Damage due to these beetles can be readily recognized by the appearance of small round holes (approximately 1.5 cm in diameter) that are stained black or brown around their perimeter.

Ambrosia beetles are quite small and average around 1/8 inches in length. In general, adult ambrosia beetles are most active in March, though they are active year-round. They have a wide distribution in the U.S. but are most common in the southern and eastern U.S.  Common U.S. species are the pitted ambrosia beetles, European shothole borers, ambrosia beetles, lesser shothole borer and Asian (or granulate) ambrosia beetles.

Adult ambrosia beetles bore into the sapwood and heartwood of dying or recently cut trees. Unlike many wood infesting beetles, these beetles work symbiotically with fungi such as Fusarium species and Ambrosiella species. The fungi (sometimes referred to as “Ambrosia”) grow in the galleries created by the beetles.  These fungi may be responsible for the death of the tree, though the beetles introduce multiple fungi species, some apparently inadvertently. As the fungus develops, it stains these galleries blue to black. The adult exit the galleries via the holes made by their parents.

The external evidence of these beetles activity can occasionally be seen as dark stains from galleries near the surface of logs. Ambrosia beetle can occasionally be seen on freshly built log houses. Season wood is rarely attacked due to the fact that the fungi on which these beetles feed require a high humidity to develop. Ambrosia beetle damage can often be seen in homes. Exit holes and galleries that are observed (including frass) are old and inactive. Such evidence does not require treatment. Larvae may continue to feed after infested wood is used in construction. As a result, they may cause concern to homeowners when the adults emerge in homes.   

Trydodentron lineatum is a widely spread species in the United State and Canada. This beetle can be a serious pest on cut trees. The majority of ambrosia beetles colonize xylem (sapwood and/or heartwood) of dying or recently dead trees, but some attack live trees. Species differ in their preference for different parts of trees, different stages of deterioration, and in the shape of their tunnels ("galleries"). However, the majority of ambrosia beetles are not specialized to any taxonomic group of hosts, unlike most phytophagous organisms including the closely related bark beetles.

One species of ambrosia beetle, Austroplatypus incompertus, exhibits eusociality, one of the few organisms outside of Hymenoptera to do so. As indicated, most ambrosia beetle species don't ingest the wood tissue; instead, the sawdust resulting from the excavation is pushed out of the gallery. Following the larval and pupal stage, adult ambrosia beetles collect masses of fungal spores into their mycangia and leave the gallery to find their own tree. This class of insects attacks living, dead, and felled trees, as well as cut logs, green lumber, and stave-bolts, often causing serious economic loss from the pinhole and stained-wood defects caused by their brood galleries.


Dinoplatypus chevrolati from Papua New Guinea, an example of Platypodinae, another species-rich group of ambrosia beetles. Image Courtesy Hulcr CC BY-SA 3.0.


Gallery of Xylosandrus crassiusculus split open, with pupae and black fungus. Image Courtesy Hulcr CC BY-SA 3.0.

To very young trees and to small twigs and branches, these may prove fatal by cutting off the flow of sap with an encircling gallery. In large tree trunks, their attacks are seldom sufficiently extensive enough to endanger the health of the tree. Most of the species confine themselves in their borings to the sapwood; others penetrate deeply into the heartwood and spoil the timber for any useful purpose by filling it with defects

Control. Prevention is the most important technique for control of these beetles. Since they not feed on the host, systemic insecticides are of little use.  Bark applications are the only known mean of chemical treatment technique known to protect trees from attack. Maintaining susceptible trees in a healthy, vigorous condition can be of help.  Most endemic species of these beetles do not attack healthy trees. They only infest weakened, dying, or dead trees with adequate wood moisture to maintain the fungi associated with and needed for their presence. On the other hand, introduced species infest both weakened and healthy trees.

Maintain a 3-inch deep mulch around the trunk of the tree to help keep the roots moist and increase the root system. The optimal size for a mulch ring is 1 foot for every inch of trunk diameter. However any size mulch ring is beneficial. Applying a complete low nitrogen fertilizer every couple of years can be of use in urban or non native soils. When faced with drought and hot conditions, periodic watering enhances the trees’ natural defensive system (sap flow). Certain species of these beetles feed on dead or dying wood.  Removal of infested material may help reduce local beetle activity. 

In general, adult ambrosia beetles are most active in March, though they are active year-round.  Females excavate galleries within the host plant just beneath the bark where eggs are laid.  Newly hatched females mate with newly hatched males on the same tree and then move on to new hosts.  Males are wingless.  The life cycle takes around 50 to 55 days and 2 generations are possible annually.

Trees that are susceptible to the attack of these beetles include, avocado, redbay, swampbay, sassafras, pondspice, pondberry, camphor tree, pecan, peach, persimmon, golden raintree, sweet gum, oak, Chinese elm, magnolia, and others.  Many ambrosia species will preferentially attack smaller trees in orchard or new plantings.  Since smaller trees are weak, they will break in wind and rain.  Some species of these beetles begin feeding at the bottom of the trunk, while others can attack near the base of twigs and branches.

Vascular wilt symptoms are a tipoff for ambrosia bark beetles.  These symptoms include flagging and dieback of entire branches.  As the beetles attack their host, they introduce vascular fungi that eventually kill the tree.  These effects can be seen best in mid- to late summer, after trees have leafed out and been exposed to summer stress.   Blue or brown staining in the vascular tissue also occurs.  Eventually dieback and tree death will occur. Sawdust like frass can accumulate at the base of trees. Pencil lead-sized holes or “shotholes” occur at the base twigs where adults exited the host.

IPM of Wood Boring Beetles.

Many of these wood pests are often introduced into structures in building material that was initially infested in lumberyards. Additional possible sources are infestation in firewood that is stored near or introduced into homes and any of a multitude infested wooden objects such as toys, art, furniture, cabinets, flooring and paneling. Dead or dying trees, outdoor piles of firewood, outhouses can serves as additional sources. In these latter cases, the beetles merely fly into houses. Some of these beetles such as black polycaon of other bostricides, anobiids or powderpost beetles are attracted to light (porch lights window light, etc.), thus putting them in close vicinity and easy access to homes.

Lumberyards and other facilities that store lumber should have strategies for preventing attack of these pests, especially true powderpost beetles. Lumber managers can follow a program of protection and removal to protect lumber from lyctids and other beetles that reinfest. These program should include periodic inspection of lumber and products that are 2 or more years old and burning those than appear infested. These procedures should also include disposal of unwanted pieces of sapwood and inspection of incoming stock to prevent introduction of wood infesting beetles. Boron products can be used to effectively for preserving and fire-retarding wood and wood products.

Inspection. The first step in any IPM program is to identify the pest causing the problem. Of course this cannot be accomplished until an infestation can be found to identify the species involved or symptoms of the presence of a given species. It is significant to determine if an infestation is active, if the species can reinfest and if control measures are necessary. Misidentification of a species involved in an infestation can result in control failure. Generally speaking, adult identification is more reliable than that of the larval stage. It follow that infestation control of wood infesting beetles in structures typically requires a high degree of knowledge and experience. Frequently pest control professional only encounter symptoms of an infestation, namely exit holes, frass, pellets, galleries, tunnels or fibrous materials. In these cases, identification can be difficult. In some cases, identification can involve destruction of products or other items. Some inspections require periodic sampling in order to determine if an infestation is active.

Prior to inspecting a property from wood destroying beetles, an operator should obtain seek information from the owner of the building of the home or other structure. This should include the age of the facility, type of wood present, extent of the problem, areas affected, known symptoms, previous treatment and especially availability of suspected pest. Once accomplish, the operator should make a thorough examination of the areas of most concern. During this inspection, findings f records should be kept including areas affected, presence and sizes and shape of emergence holes, extent of damage (e.g. number of emergence per square inch), amount and type of frass, wood moisture of content and type of wood infested. Of most concern the inspections should include a thorough search to find specimen of the damaging pest. The PCO should keep in mind that there is a wide variety of materials or products where these beetle can infest, especially that that are capable of reinfesting. Commonly infested materials include wooden shipping crates, decorative indoor plant baskets, decorative driftwood, wooden artifacts, carved wooden art objects, broom handles, old baseball bats, firewood stored indoors, wooden picture frames, wicker laundry baskets, bamboo and bamboo products, exotic wood ornaments, wood toys, wicker furniture, bamboo furniture, woven Easter baskets, wooden pallets, and certainly many types and parts of wooden furniture flooring.

It is critical to determine is an infestation is active. Of course the first step is to search for specimens. As indicated, quite frequently the customer has even collected and saved specimens in variety containers. Side story! I frequently receive specimens of a variety of bottles. In one situation, the specimens were supposed to be dust mites. The label on the bottle read collected after douching. Needless to say, I didn’t open that bottle.

If specimens are not available, attention should be played to emergence holes. It should be noted, the presence of emergence holes is not always an indication of an active infestation. It is also not an indication of duration of an infestation. Emergence holes that are the same color of surrounding wood are typically an indication of olds activity. Frass that is yellow, caked or covered with dust is typically old. If needed frass can be removed and rechecked at a later date to determine the present of new feces. This technique is not always a reliable means of detecting an active infestation. Unfortunately, vibrations produced by any number activities in and outside a structure can dislodge small amounts of frass from old, inactive exit holes. An additional technique that is used to determine the activity of an infestation is to circle all emergence holes in an area and return at a later date to determine if any new holes have developed. Finally an area near the emergence holes can be painted and then check a few months later. In the case of fine furniture or cabinetry, small pieces of masking tape can be used to cover emergence holes instead of marker or paint. Of course these techniques will work best during warm temperatures when these beetles are most active and when they are likely to emerge.

It is worthwhile to explain to customer that these techniques are needed to make sure their infestation is or is not active and it may take up to several months to do so. They should also be told that this could save them the cost of possible expense of control. It should also be explained that these beetle develop very slowly (up to several years in some cases) to cause any significant damage.  Of course if the customers find any new specimens, they should contract the pest control operator. They will likely do this anyway.

With some types of wood beetle infestation, their chewing activity can be heard, especially late at night. In some cases it may be worthwhile to use a stethoscope to try to detect these sounds in walls or other locations. Active infestations can be detected with X-ray equipment. I have seen this used in a lawsuit case. It was quite effective but not cheap.

When conducting an inspection, it is worthwhile to determine the moisture content of suspect wood. Moisture content of wood above 15% is conducive to attack from many wood destroying beetles, speeds up their development, contributes to reinfestation and produce larger infestations. In order to minimize the chances of reinfestation or even infestation of these beetles, wood moisture content should be maintained between 8 to 12 %.  Excess moisture in wood is typically found in basements, attics, and crawlspace. Plumbing, foundation and roof leaks, poor exterior grading and other conditions that lead to excess wood moisture content should be corrected. Installation of soil moisture barrier and increased ventilations to crawl spaces and attic vent when needed are of value in minimizing infestations of these beetles.

Control. If an infestation of these beetles is not well-developed and determined to be confined to a small area, it is frequently practical to remove the wood and replace it with treated material. This approach needs careful consideration. In order to be sure of elimination of an entire infestation, it may be advisable to remove wood past the suspected area of infestation.

Although not commonly used by professional pest control operators in the United States, small wooden objects can heat small wooden items, but not those containing fabrics, pelts, or paints heated at 120° to 140° F will kill all stages wood infesting beetles. You also can place items in a deep freezer at 0°F for 72 hours. Longer treatments might be needed if the wood is thicker than 2 inches.

Removal and replacement of infested wood may be required to eliminate beetles. Destroy infested wood by burning or take it to a landfill. Where removal isn’t possible, liquid insecticides can be applied to bare structural wood. The most effective and safest materials are pesticide formulations containing sodium borate (e.g., Tim-Bor and Bora-Care), which a licensed pest control operator must apply. These materials must penetrate wood to kill beetle larvae that are within, so finished wood can’t be successfully treated. Depth of penetration is enhanced in moist wood; if moisture is less than 15%, penetration might occur only in the top 1/4 inch.

For extensive powderpost and deathwatch beetle infestations within a building or where inaccessible structural parts of a building are involved, many professional pest control operators offer whole-building fumigation. Homeowners should bear in mind this method doesn’t prevent reinfestation

Insecticide Treatment. Insecticide treatment for wood boring beetles includes wood injection, partial or whole structure fumigation and surface application of pesticides.                                                                                                 

Funigation. The use of whole structure fumigation is typically utilized when customers wants a guarantee of elimination of an infestation of these beetles. It is also considered the only technique that can be use to control these pests when widespread infestations extend into inaccessible locations in structures.  Sulfuryl floride (Vikane) is most commonly used fumigant in these cases. Methyl bromide use has been phase out because of its effect on the ozone layer of the atmosphere. When properly applied, sulfuryl floride will readily penetrate the whole structure and kill all stage of these pests. One disadvantage of its use is that it provides no residual activity against reinfestation of these beetles. Another disadvantage is that it is quite costly and for controlling true powderpost beetles, the label recommends using 10 times the dosage recommended for drywood termites and 4 times the drywood termite dosage for old house borers. These higher dosages are required to kill the egg stages of these beetles. As a result, this procedure can be very experience.

Surface Treatment Applications. The application of liquid pesticide to surfaces typically will not immediately control wood destroying beetles larvae feeding deep wood. It residuals pesticide used, they will kill some of the larvae in the wood and the adults as they emerge through the treated areas. These treatments will also aid in preventing reinfestation depending on the residual activity of the product. Unfortunately, most of the available chemicals that are available for this use have a very limited residual activity-, a month at best. The major problem is that approximately 80% of the structural wood found in home occurs in inaccessible areas. The application of liquid pesticides on wood in structure should closely follow label direction and state regulations.

Heat. Whole house treatment with heat is used as an alternative to tenting for drywood termite control. Some companies also advertise whole house heat treatment for wood destroying beetles. Almost all insects cannot survive extended temperatures above 115 degrees F. Insects including wood destroying beetles are very small. As a result, they have a very large surface areas in comparison to their total body mass that is need to store water and other fluids. Consequently, they are very susceptible to dehydration and when exposed to high temperature simply dry up and die. To digress, the question may arise as to how insects survive in many deserts when temperature often reaches 115 F or above. Of course the answer is that insects live in a microclimate as opposed to the macro climate we live in. When desert temperatures reach 115 F or more, insects simply seek a cooler location such as the surface of a leaf where the temperature is much lower. The reported lethal temperature for wood destroying beetles that are reinfest vary from 25 to 33 F and exposure times from 5 minutes to a few hours depending on the species concerned. Unlike fumigation, the eggs are just as vulnerable (possibly more-smaller size) to heat as the rest of their stages of development. As with fumigation, heat does not provide any residual control. Unlike fumigation, heat may not be effective in attaining 100 % control as it may not penetrate all areas of the structure. In this case, with a kill in the high 90s F there would still be an infestation. Total eradication of wood infesting beetles can be obtained when infested objects are placed in vaults or special trailers and then heated to the desired levels.

Sirex Wood Wasp.

This species is endemic to Europe, Asia, and northern Africa, where it is generally considered to be a secondary pest. In it is endemic range, this species attacks Scotch, Austrian, and maritime pines. It is an introduced species in Chile, New Zealand, Uruguay, Australia, Brazil, Argentina, and South Africa. In these countries, this wasp attacks exotic pine plantations, and it has caused up to 80% tree mortality. The majority of these planting have North American pine species, especially Monterey pine. Additional susceptible species include ponderosa, slash, lodgepole, shortleaf, and jack pines. This was first discovered in North America in 2004 in a trap in New York. White pine is also attacked but is less preferred. Pines 6 feet and larger are susceptible and stressed, suppressed and crowded pines seem to be favored. It is thought that the sirex woodwasp can spread approximately 25 miles per year.

Identification. The sirex woodwasp bears a sturdy, cylindrical body with an apically pointed abdomen. These wasps characteristically lack a petiole or narrow waste that connects the thorax to the abdomen. The female is 0.59 to 1.42 inches long; males are slightly smaller measuring 0.35 to 1.26 inches in length. Both sexes have long, black filiform antennae. The bodies of the males are black, with the exception of orange central abdominal segments. The wings are yellowish and somewhat translucent. The front legs are yellowish-orange and third or hind pair is black and much larger and thicker than the first or second pair. The females are iron blue and have orange legs and black filiform antennae. This is a characteristic distinction from Sirex juvencus, which has red antennae. The females also bear yellowish wings. The elongate, well-developed ovipositor is apically attached to the tapering abdomen. Both larvae and adults have strong mandibles to chew though wood.

The larvae of this species are creamy white, legless, and have a distinctive dark spine at the apex of the abdomen. There are currently no keys available to identify different species of sirex wasp larvae. Proper identification of the adults should be accomplished by knowledgeable taxonomists

Figure 3. Sirex noctilio—larva and close-up of posterior spine.

Characteristic shape and terminal spine of sirex larva. Image Courtesy USDA.

Sirex noctilio female 3 small.jpgSirex noctilio male cropped.jpg


Female sirex wasp with elongate ovipositor, Male with orange middle segments of the abdomen and black hind legs. Images Courtesy David R. Lance, USDA CC BY-SA 3.0

Infestations of this species increased in the Great Lakes area from 2004 on and now are considered an invasive species in several states. It had reached Ohio, Pennsylvania, Vermont and Michigan by 2009. This species can swarm between 12 and 31 miles, and is now predicted to take to about 2050 to spread to the far southeastern United States. In New York, most damage has occurred in plantation of Scots, Austrian, and red pine. These plantations were established in the early to mid-1900s and were often unmanaged and are now crowded, stressed and underperforming. Of course this type of condition would be susceptible to the attack of this and other wood boring insects. The death of these weakened trees is not having a large economic or environmental effect in New York. However, damage from this wasp has the potential of creating significant damage in the Southern and Pacific Northwestern United States. The projected economic damage to these forests is upwards of $17 billion dollars with hundreds of thousands of destroyed trees.

As a result, forestry authorities greatly increased their pest control techniques and initiated education program: these include warning not to transport firewood over large distances or to avoid storing it too long. The Invasive Species Specialist Group (ISSG) of the IUCN has graded the wasp as heavily invasive.

Biology. Flight activity begins in the late summer to early autumn, depending on weather and location. Males emerge from their pupae earlier than females and swarm to eventually gather around treetops. Once mated, females search for suitable host trees, preferring weak and dry wood. They are attracted to monoterpenme hydrocarbon compounds that are produce by weaken pine trees. When a tree is stressed due a lack of available water, disease, cutting or exterior injuries, these compounds are released from the bark.

Using their long ovipositors, females drill a hole through the bark to reach the xylem. Once there, they deposits a single egg, spores of the fungus Amylostereum areolatum and a phytotoxic secretion. The fungus and mucus act together to kill the tree and create a suitable environment for larval development. Smaller females may lay 20 eggs, while the largest can deposit up to 500. Female are short lived after oviposition.

Larvae of this species develop through arrhenotoky, namely where male larvae develop only from unfertilized eggs and females only from fertilized eggs. Typically, 10 males are produced per female, but the ratio varies from 20:1 to 1:1. Hatching may vary from 8 days to several months, depending on weather or other environmental conditions; the former period is more likely. At the optimal temperature (77 °F), they hatch in 10 to 12 days. Although the larvae hatch quicker at 86 °F, they are 20% more likely to die when exposed to this temperature. With lower temperatures, development is slowed, and below 43 °F, the larvae die. An adequate presence of the fungal mycelium is crucial for hatching; the fungus prevents the wood from drying out. Without moisture, hatching is not possible. The tree can ward off the infestation of this wasp and other wood boring insects by flooding their boreholes with resin or halts the fungus by producing a wall of polyphenols.

There are 6 to12 instars. The first two feed on surrounding fungal tissue, until reaching inner wood. The third and fourth instars eat through the final summer wood and ultimately reach the heartwood. The larvae mainly consume the fungal mycelia.  Once fully mature, they pupate a few inches under the bark. Once emerged from the pupae, adults eat through the bark leaving round emergence holes that vary from 1/8 to 3/8 inches in diameter. Development from hatching to pupation varies from 10 days to 2 or more years, depending on prevailing temperatures. Temperature is the main factor that determine how fast all insects pass through their development. The lower the temperature, the longer they take to develop.

Sirex woodwasps can attack living pines, while native woodwasps species attack only dead and dying trees. As indicated, sirex woodwasps are drawn to suppressed, stressed, and injured trees for egg laying.  As populations advance, foliage of infested trees initially wilt, and changes color from dark green to light green, to yellow, and ultimately to red. Larval galleries are tightly packed with very fine sawdust.  

Unlike any other species of Siricidae, the sirex woodwasp can damage and even kill relatively healthy trees.  However, the wasp mainly infests weakened trees; only when populations are high, do the insects also attack intact and healthy trees. Because the wasp larvae and the fungus need healthy wood, the Sirex woodwasp does not infest dry or dead timber. However, wasps may hatch from processed wood which was already infested

Natural enemies and parasites.


Rhyssa persuasoria specializes on the Sirex woodwasp and its relatives. They lay their eggs on the wasp larvae. Image Courtesy USDA,

There are parasitoid wasps, many native to North American, which could assist in managing sirex woodwasp populations.

Many species of birds feed insects, including the sirex woodwasp. The adults are frequently consumed by swallows and swifts, both of which prefer males. The black and great spotted woodpeckers consume some larvae, but do not specialize on the sirex woodwasp. Although the avian species may add to the decline of this wasp, they certain will not control this species.

Deladenus siricidicola, a parasitic nematode, has been successful in minimizing some infestations. The nematode infects the woodwasp larvae and ultimately sterilizes the females. These females lay infertile eggs that are filled with nematodes. As nematode populations grow, they can maintain sirex woodwasp populations below damaging levels. Easy to rear in the lab, this species can be injected into infested trees.


Carpenter Ant Biology and Control

By Dr. R. S. Kaae and Patricia Kaae

Carpenter ants are of minor consequence in some areas of the United States and of major concern in others.  Factors that appear to determine their importance are humidity, other sources of moisture and, of course, availability of wood, especially cut or fallen timber.  Generally speaking higher humidity is conducive to their presence and establishment. It follows that on the West Coast carpenter ants are more of a problem in the Pacific Northwest than in Southern California.  Similarly in Southern California they are more of a problem in the mountains than the lowlands. A few studies have indicated that these insects are more of a problem than termites in the Pacific Northwest. In this area, one study, which extended over a 5 year period, 23 pest control companies reported treating 824 separate carpenter ant infestations.  Other sources indicate that over a 21 year period all existing homes in Washington State will have been infested with carpenter ants. This amounts to 21,900 infestations per year that are treated professionally. Also, it is estimated that homeowners treat an equal quantity of these pests.

Identification. The homeowner sometimes confuses the appearance of winged carpenter ants with the presence of swarming termites.  There are some very basic differences between the two. A narrow waist or petiole in carpenter ants specifically connects the junction between the thorax and abdomen. In termites, the thorax and abdomen are broadly joined.  Additionally ants have 1 or 2 nodes or bumps on the top of the petiole.

An additional distinguishing feature is the appearance in the antennae.  Ants have elbowed or geniculate antennae. In this case, the first antennal segment (where it attaches to the head) is generally long with the remaining segments being much smaller.  In termites, all antennal segments are pretty much the same size and shape.


Carpenter ant antennae. Note the elongated first segment in the ant antenna.  Image Courtesy of Jim Kalisch, Nebraska Entomology

Finally, termites differ structurally from carpenter ants by the appearance of the wings in alate forms. Termites belong to the insect order Isoptera.  Iso in Latin means equal, while ptera means wing and, in the case of the termites, the front and backwings are of equal size and shape. In winged ants, the hindwing is considerably smaller than the front.  Also there are many more veins in the termite wing than there are in the ant wing.

Carpenter ants belong to the genus Camponotus.  There are a number of species in the United States.  Many people think of them as large black ants. These are the largest of our domestic ants, with the worker castes ranging from 6 to 10 mm in body length.  The queen ants can reach 13 to 15 mm in length.

This genus contains the largest of our domestic ants, with the worker caste being highly polymorphic, meaning that there is a considerable variation in size.  The most common type of domestic ants that approach their size is the black and red harvester ants. When viewed from a dorsal angle, these ants appear quite similar.

 However, separation of these 2 groups is fairly easy from a side view.  Carpenter ants have 1 well-developed, erect node or bump on the top of the petiole; the harvester ants have 2 less developed, rounded

 nodes.  In addition when view from the side, the profile of the thorax of carpenter ants appears rounded and humpbacked. Finally harvester ants have a series of long curved hairs on the underside of the


Pogonomyrmex barbatus casent0006306 profile 1.jpghttps://upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Camponotus_sp_Tanaemyrmex.jpg/1280px-Camponotus_sp_Tanaemyrmex.jpg

Comparison of harvester and carpenter ants.  Left. Harvester ant image Courtesy Antweb. org April Nobile. Left Carpenter ant image Courtesy Muhammad Mahdi Karim GFD 1.2                                                                                                            

Life Cycle. As do all Hymenoptera, carpenter ants exhibit complete metamorphosis with an egg, larval, pupil and adult stage. The eggs are produced primarily by the queen, although in her absence, workers have the capability of laying eggs: however, eggs produced by workers typically develop into male ants.  The colonies of some species may have more than 1 queen. Once hatched, the larvae pass through several molts prior reaching the pupil stage. The larval stage of ants is a legless grub with a hook-like head and thorax.


Larval stages of a worker and queen carpenter ants-characterized by the absence of legs and a hooked head and anterior body region. Image Courtesy of Vopak Inc.

Ants have a coarctate type pupa, which is characterized by a pill capsule in shape. Hardening of the exoskeleton of the last larval instar develops into the outer capsule of the pupae. Inside this capsule is the actual pupa, which appears as a mummified replica of the adult. The encased pupae are often mistaken as the egg stage of ants.

A queen in a mature colony may lay a dozen or so eggs a day. These eggs typically hatch in about 3 weeks, and the entire life cycle from egg to adult may be completed in as little as 9 weeks.  Of course, as with all insects, the rate of development of carpenter ants is totally temperature dependent. At 80 degrees F, the life cycle may take 9 weeks and the same insect when raised at 60 degrees may take several months to complete development.

Caste Determination and Colony Det

In mature carpenter ant colonies, there are 3 basic castes, namely the queen(s), workers and males or kings. The workers are sterile females and develop from fertilized eggs.  In most species of ants, there is a degree of polymorphism in the worker adults, meaning that there are different sizes of workers. When polymorphism exists the larger workers typically defend the colony, while the smaller forms carry out other duties of the colony (e.g. feeding the larvae, excavating the colony).



Left. Different sized worker ants. Right, Winged and non-winged queen. Image Courtesy. Image Courtesy Gamekleeper CC BY-SA 3.0

The number of each caste in a colony depends on the species and age of the colony. Very mature colonies may have between 3,000 and 4,000 workers.  In the late spring or early summer, in a mature colony winged male and female ants swarm. These individuals have the potential of forming a new colony.  If the female is mated, she will typically burrow beneath the soil, under a rock or into an old drywood termite gallery. At that point, she breaks off her wings, forms a small cavity and waits a few weeks for the eggs to develop in her ovaries.  Her large wing muscles are then dissolved, passed into the blood and carried to the eggs and utilized in yolk development. Once the eggs mature, a dozen or so are deposited. Once the young hatch, the queen cares for and feeds the developing larvae on secretions from her salivary glands. Because the queen does not leave her nest during this time, she can only feed the developing larvae from stored fats in her abdomen and dissolved wing muscle nutrients. The adult workers from this first brood are small and are normally referred to as the minimae.  Once developed, these workers leave the nest in search of food and water and then assume the duties of feeding the next generation of brood. By midsummer, the second generation has developed into workers. It generally takes 3 to 5 years for full development of a colony; the maximae (larger workers) are not produced until the third year. Swarming forms can be seen in the colony by the beginning of the second year.


 Right. Swarming king and queen ants from mature colony Image Courtesy "Fir0002/Flagstaffotos" CFDL1.2.  Right. Ants (king and queen) mating prior to beginning a colony. Image Dave Parker CC BY-SA 3.0

As with other ant species, carpenter ants tend to form satellite colonies that are associated with their main colony.  These colonies may be loosely connected via pheromone trails and it is not uncommon for ants from the satellite colonies and the main colony to intermingle and even transfer brood from one colony to another.  Normally brood is only moved from mature colonies to satellite colonies. This is a means of expanding the size of the overall colony (satellite colony plus main colony). Typically satellite colonies do not contain a queen, eggs or young larvae but do contain older larvae, pupae workers and winged males.

Foraging Activities

As do many other species of ants, carpenter ants forage with the use of trail following pheromones.  When initially seeking food, individual ants forage at random; however, when an ant finds a good source, as it heads back to the nest, it drags its abdomen on the ground releasing small amount of trail following pheromone (produced in its gut).  Once reaching the nest, it shares the food with the other workers alerting them to presence of the source. Once these ants now requited leave the nest, they follow and reinforce the chemical trail that leads to and from the food. The chemical itself is not long lived. As a result, it needs to be constantly reinforced by the foraging ants.  This obviously serves to eliminate the problem of a trail eventually leading to a depleted source of food.

Carpenter ants forage primarily in the spring and summer months in temperate climates, with peak activity occurring between 4 AM and 8 AM and 71 to 74 F.   However, the time of day is going to vary depending on the geographical location and if the infestation is located indoors or outdoors. For example in warmer areas outdoor infestations primarily forage any time of the day in the spring and fall when favorable temperatures exist.  During the hotter summer months of July and August, they primarily forage during the night; again, favorable temperatures dictate this.

Only 2 to 3 % of the total nest population forages at any one time.  As a consequence, it does little good to spray foraging workers. In fact, when the trails of many ant species are spayed, thus eliminating the foraging workers, the colony becomes stressed.  The colony tends to bud or form new queens and split up, thus forming more colonies and the potential for an even heavier infestation.

The main diet of carpenter ants is honeydew.  Aphids, leafhoppers, mealybugs, soft scales and some of the other less known insects produce honeydew.  These insects suck the sap of leaves and other plant parts, but typically do not digest it all. The excess is passed from the anus in the form of honeydew or partially digested plant sap.  Many ants, including carpenter ants, have a mutualistic relationship with these insects in which both parties benefit. The ants benefit by obtaining food from the aphids and their relatives.  The homopterous insects in turn are guarded by the ants and protect them from the many types of other insects that feed on them. The ants actually milk the aphids. It is not uncommon for an ant to approach an aphid and stroke its abdomen with its antennae, resulting in the production of a drop of honeydew.  Typically the minimae, or smaller of the different sized workers, guard the aphid while the maximae, or largest of the 2 forms, collect and carry the honeydew back to the nest. It is quite easy to distinguish between a worker that has not recently collected honeydew and one that has. The abdomen of an ant that has recently collected honeydew becomes greatly extended.


Ant collecting honeydew from aphids.  Image courtesy of Jmalik at English Wikipedia CC BY-SA 3.0

Carpenter ants feed on materials other than honeydew.  Another essential component of their diet is insects, although they rarely eat honeydew-producing insects.  The protein the ants receive from this source is essential for brood production. Carpenter ants do not feed on wood, although some species can do considerable damage to homes when expanding their galleries.  

When carpenter ants are found foraging in the home, it does not necessarily mean that the main nest is found in the structure.  A recent study indicated that approximately 75% of the time, when these ants were found foraging in the home, they originated from outdoor sources; in this case, the most common location was dead trees.  Of course this figure would likely change drastically in more urban settings. Additional findings were that it was very common for carpenter ants to set up smaller satellite colonies within structures; however, these satellite colonies typically were connected to the large parent colonies that were located outdoors.

Outdoor colonies have little difficulty entering a home to forage for food.  Studies indicate that old homes are as readily infested as new homes. These ants can easily travel through or on wall voids, including insulation, heating ducts and water pipes.

Inspection Procedures.

Inspection for carpenter ants should be based on a thorough understanding of the biology and behavior of these insects and should incorporate both indoor and outdoor locations.  It is always advisable to thoroughly interview the occupants of the structure; they are likely to have a fairly good idea as the locations of the problems.

The most common locations where indoor nests of these ants are likely to occur are attics, window frames, floors, cedar/plywood siding, moderately slope roofs, wall voids and crawl spaces.  Keep in mind that situations that are favorable to carpenter ant infestations are areas of high moisture content (both inside and outside the structure) and rotting wood with fungal infestations.

Carpenter ant nests are typically located within wood and therefore not readily visible.  One means of detecting their nest location is to follow the foraging trails. Of course this is only possible if it is the right time of the year and day when these ants actively forage.  Even if active, the trails themselves may not necessarily be readily visible. Outdoor hidden trails may follow the shallow roots of trees, occur under leaf litter and other debris, pass under patios and driveways and even occur as shallow tunnels just below the soil.  However, more time than not, the trails occur above ground and are detectable. Above ground trails frequently are located immediately next driveways and lawns, the outside foundation of houses and even follow the natural contour of the ground. Once detected, these trails are detected; it is advisable to keep track of where trails and nests are located.  Studies indicate that 90% of reinfestations occur along previously used trails and in old nest sites.

Outdoor inspection should be thorough, keeping in mind that most structural infestations originate in such locations (primarily in tree stumps), either directly as foragers or as the main outdoor nests of indoor satellite colonies.  A good indication of the latter is that foraging ants carry later instar larvae from an outdoor source to indoor satellite colonies. If more than 1 colony is found, it is important to determine if the ants come from the same group (e.g. main and satellite colony) or from different colonies.  Ants from the same colony group will not fight, but ants from different heritages will.

It may become important to distinguish wood damage due to carpenter ants than that caused by drywood termites or even subterranean termites.  Carpenter ants frequently occupy abandoned termite colonies. In this case the galleries or tunnels of each appear very similar. As most pest control operators know,  the galleries of drywood termites typically cross the grain and growth rings of the wood and those of subterranean termite more or less run with the grain and growth rings . In the case of carpenter ants, the walls of the individual tunnels take on a polished appearance.


Left to Right.  Drywood termite gallery with tunnels crossing the grain and growth rings.  Image Courtesy Dr. Kaae. Subterranean termite galleries crossing the grain and growth rings. Image University Nebraska. Carpenter ant galleries with polished appearance. Image courtesy of Bjørn Fritsche CC BY-SA 2.5

When making an inspection it may become necessary to distinguish between the types of frass produced by drywood termites and carpenter ants as both expel this material from their galleries.  In the case of drywood termite their frass is pellet-like in appearance with the individual pieces about the size of a grain of sand. In the case of carpenter ants, the frass is shredded and typically contains insect parts.


Carpenter ant frass mixed with insect parts. Image Courtesy of Jim Kalisch, Univ. Nebraska Entomology.

Finally large colonies of carpenter ants are somewhat noisy.  It is not uncommon to be able to hear their low level rustling in the wall.  Some companies use the aid of listening devices for this purpose.

Prevention and Control.

The degree of prevention and control needed of is partially depends on how extensive and persistent of a problem exist.  Any or all of the following may be needed.

Adequate ventilation to reduce moisture in crawl spaces, attic and basements.

Elimination of ground wood contact.

Reduce vegetation contact with structure-reduces entry site for ants.

Chemical treatment of wall voids.

Proper vapor barriers in crawl spaces.

Adequate drainage leading water away from structure and reduction of other water sources that may lead to fungal infestations.

Reduction of stumps and other wood on premises that will support outside colonies.

Treating Nest Sites Indoors. Either physically remove indoor nests or treat them with an insecticide labeled for ant control indoors. Use insecticidal dusts and/or aerosols to eliminate carpenter ant infestations indoors. Apply small amounts of dust into voids where the ants are known to be nesting, are suspected of nesting, and/or in voids that they use when foraging. Dusts must be placed into the voids so they will not be contacted. Since dusts become airborne very easily, it is advisable to wear a protective mask when applying dusts.

Apply dusts so a very thin film settles in treated areas. Place dusts behind electrical outlets and switch plates and in the voids under window sills. Small holes (1/8 inch) may also be drilled into drywall in areas where ants are suspected of nesting. Place dust into the void and patch the hole with drywall cement.

Aerosol formulations may also be used when indoor ant nests are visible and accessible. For example, when nests are uncovered during inspection, spray all ants with an aerosol before they can disperse. Never use water-based or other wet formulations in voids. Wet formulations not only damage drywall, insulation and wood molding, but there is a danger of electrical shock and/or fire when using liquids around electricity.

Treating Carpenter Ant Colonies Outdoors. Outdoors, pour a water-based, liquid insecticide directly into carpenter ant nests located in tree holes. Use enough insecticide to thoroughly saturate the entire nest. This may require pouring 1 gallon or more of liquid insecticide into the structure. If a nest is difficult to reach with a liquid spray, it may be necessary to drill a small hole (¼ to ½ inch) into the top of the suspected nest location. This allows the liquid insecticide to be introduced and to flow downward through the nest. When treating carpenter ant nest sites inside and outside, the choice of a particular product or brand name is not as important as the choice of formulation and the direct treatment of ants and/or nest sites. Carpenter ants are not known to be resistant, or immune, to any insecticide.

Often the nest cannot be found or, if found, cannot be easily treated. Under these circumstances, baits may be used. Baits are an effective means of controlling ants in some cases. Indoors, use liquid baits and baits contained in childproof, plastic bait stations; outdoors, use liquid and granular baits. For liquid baits, soak a small cotton ball and place it on a piece of aluminum foil in areas where ants have been seen. Granular baits should be delivered on 2 or 3 small piles (about the size of a quarter) placed in areas where ants have been observed (e.g., next to semi-permanent trails and trees containing nests).

Perimeter treatments are useful in keeping ants from entering structures. With perimeter treatments, outside walls should be sprayed with a water-based liquid insecticide. Outside walls can be sprayed around the perimeter of the structure and 2 to 3 feet up, on the ground (including shrubbery, mulch, flower beds, etc.) and 5 feet away from each wall. Perimeter treatments should be re-applied every four to six weeks during the summer and within a week following a heavy rain. Typical perimeter treatments often require 7 to 10 gallons of liquid spray.


  1. All bostrichid beetles are small, have a head that is hidden from a dorsal angle and pyramid shaped spines on the top of the prothorax.

  2. Bostrichid beetles typically deposit their eggs in tunnels prepared by the adults.

  3. The lead cable borer on occasion causes problems to the telephone industry.

  4. Wood infesting anobiid beetles typically prefer to attack wood that is 10 years or older

  5. The furniture beetle is one of the major wood boring pests (including termites) in Europe and New Zealand and their control amounts to a fair proportion of the pest control operators business in these areas.  This beetle is not nearly as important in the US.

  6. The bamboo borer is a major pest of dried bamboo in much of Asia and has been shipped all over the world but hasn’t become a major pest in the U.S.

  7. The mating call of the deathwatch beetles is superstitiously (in old England) supposed to be an omen of impending death.

  8. Powderpost beetles can readily be distinguished from the other 2 families of beetles that reinfest wood by the presence of a 2 segmented clubbed antennae.

  9.  In the United States, there are 20 species of true powder post beetles, 10 which are of economic concern.

  10. In the continental U. S,  powderpost beetles are second only to the termites as far as insect damage to lumbered wood; they confine their damage to large pored hardwoods such as oak, hickory, ash and bamboo.

  11. Powderpost beetles are nocturnal and do not fly to lights, a behavior that may be useful in detecting an infestation.

  12. Powderpost beetles eggs are deposited in the pores of hardwood, which are exposed when the wood is cut or the female may open them herself.  Finely sanded, painted, varnished or other finished wood is not normally suited for egg laying.

  13. Damage from powderpost beetles cannot be detected until the adults emerge from the infested wood.

  14. Three factors primarily determine the acceptability of hardwood to the attack of these powderpost beetles.  These are pore size and starch and moisture content.  The primary nutrient of wood to lyctids is starch, as they do not digest cellulose and other components.  

  15. Powderpost beetles attack new lumber as opposed to old since starch is lost with aging.  Their larvae can live in wood with water content between 8 and 32 %.  Green lumber contains around 50% water and is not accessible to attack by these beetles. 

  16.  Powderost beetles prefer hardwood with large pores as opposed to wood with fine pores, as is not readily accessible for deposition of the eggs.

  17. Since powderpost beetles are small and probably don’t fly far from these natural sources of food, infestations in structures and wooden products generally begin by infested wood being built into or brought into the structure or from nearby infested.

  18. Sanitation becomes a very important factor in preventing infestations of powderpost beetles.  Since most of these beetles have a relatively long life cycle, the periodic elimination of susceptible scrap or excess wood is essential and quite effective.

  19. Powderpost beetles are typically not capable of infesting lumber that is finished with varnish, paint or even fine sanding in some cases. Such finishes should also include the end cuts. Once an infestation is established in a structure or other object, possible controls include the use of heat, fumigants and even toxic solutions in some cases.

  20. Longhorned beetles, metallic wood boring beetles and powder post beetles typically cannot reinfest wood.

  21. The bark beetles are one of, if not the most important pests of our forest pests.  Huge numbers of these beetles are attracted to trees that are weakened by drought, forest fires, diseases or merely by lack of sufficient light (under-story trees).  In these conditions, or even if a tree is merely cut, its natural defense of sap flow is greatly reduced. Trees in this condition release chemical odors that attract these beetles.  In addition, once a beetle is attracted to a tree and begins to feed, it releases an aggregation pheromone that is produced in its gut. This chemical attracts other individuals of the same species, which in turn releases more pheromone and in time thousands of beetles are attracted to the weakened tree.  This mass attack eventually kills the tree. This is a very effective means of finding susceptible trees.  Healthy trees do not release chemical odors that are attractive to these beetles and even if a beetle were to fly to and attack a healthy tree, it would be drowned by the sap flow prior to releasing the aggregation pheromone.

  22. Natural enemies of the eucalyptus longhorned beetle were introduced from Australia.  As a result, biological control along with better cultural care of eucalyptus have gradually but eventually dramatically reduced the populations of these wood boring beetles throughout their distribution in the state.

  23. The warf borer is thought to be endemic to the Great Lakes region of North America; reportedly it has caused considerable damage to dock timber in this region. Buried wood may harbor the larvae. Reportedly, there was an increase in numbers of this insect in London after WWII. Masses of timber were buried via bomb blasts. These were infesting the floors of gasoline stations, apartments, and even telegraph poles.

  24. On occasion adult buprestids and longhorned beetles emerge from the walls and other wooden structures in the home.  Invariably these are surviving larvae that have completed their development and “were built into the house”. 

  25. The new house borer and old house borer are long horned beetles that attack only soft wood and are capable of reinfesting lumber.

  26. Ambrosia beetles do not feed on wood but feed on fungi that grow on the walls of their tunnels.

  27. Ambrosia beetles do not reinfest and cannot survive in seasoned wood and therefore are not a structural pest.  However, since their galleries do extent deep into trees, it is not uncommon to find seasoned wood or wood products that contain damage due to previous infestations.  In this case, all damage was done prior to the production of the lumber or manufacturing of the product.

  28. Sirex woodwasps can attack living pines, while native woodwasps species attack only dead and dying trees. As indicated, sirex woodwasps are drawn to suppressed, stressed, and injured trees for egg laying.  As populations advance, foliage of infested trees initially wilt, and changes color from dark green to light green, to yellow, and ultimately to red. Larval galleries are tightly packed with very fine sawdust.  

  29. Telephone pole beetles are also referred to as vault beetles, due to the fact that they are occasionally found in large numbers in bank vaults. The larvae are wood-borers that in nature feed on moist and decaying chestnut and oak logs. It is no coincidence that the steel of many bank vaults are built over chestnut or oak panels and over time water from the panel condense resulting in partial decay-all the requisites for beetle development.

  30. When foraging carpenter ants  only a small percentage (2 to 3%) travel along the trail at any one time.

     31. An effective means of controlling carpenter ants is spraying the foraging workers

     32. In nature the main diet of carpenter ant adults is honeydew although they will also readily feed on other insects.

     33. In forested areas, when carpenter ants are found foraging in home they typically are coming from an outdoor location.

     34. As with other ant species, carpenter ants tend to form satellite colonies that are associated with their main colony.  These colonies may be loosely connected via pheromone trails and on occasion ants from the satellite  colonies and the main colony to intermingle  and even transfer brood from one colony to another. Normally brood is only moved from mature colonies to satellite colonies.  This is a means of expanding the size of the overall colony (satellite colony plus main colony). Typically satellite colonies do not contain a queen, eggs or young larvae but do contain older larvae, pupae workers and winged males.

     35. Very mature colonies of carpenter ants may have between 3,000 and 4,000 workers.  

     36. The frass of carpenter ants is typically coarse and contains insect parts.

     37. Carpenter ants frequently occupy abandoned or empty termite colonies.  In this case the galleries or tunnels of each appear very similar and are hard to distinguish from each other.

     38 Large colonies of carpenter ants are somewhat noisy.  It is not uncommon to be able to hear their low level rustling in the wall.  Some companies use the aid of listening devices for this purpose.

     39. Adequate ventilation to reduce moisture in crawl spaces, attic and basements may be helpful in controlling carpenter ants.

     40. It generally takes 3 to 5 years for full development of a colony of carpenter ants and the maximae (larger workers) are not produced until the third year.  

     41. Adequate drainage leading water away from structure and reduction of other water sources that may lead to fungal infestations associated with carpenter ants.