Wood-Infesting Insects
Insects That Do Not Eat Wood But Use It for Nesting
Forest Health Guide for Georgia Foresters
Written by Terry Price, Georgia Forestry Commission
Adapted for the web by the Bugwood Network
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Carpenter ants, carpenter bees, and many solitary wasps and bees are common in log houses and other wooden structures. These insects are primarily a nuisance, and are not likely to cause serious damage quickly. Carpenter ants nest in stumps or tree cavities outside the home and enter homes to find sugar or organic matter as food. Ant workers, 1/4 to 1/2 inch long and reddish brown to black, do not eat wood, but excavate shallow nests with smooth (as if sanded) walls, preferably in moist, decaying wood (Figure 26A and 26B).
Figure 26A - Carpenter Ants
photo by Van Waters and Rogers |
Figure 26B - Carpenter ant galleries
photo by R. Werner |
Preferred nesting sites are readily available inside between wall studs, around windows and doors, and in heartwood log centers in many houses. The nests cause only minor damage unless large colonies are present for several years. If the main nest of the ants is outside, it must be located and treated for satisfactory control. Reducing moisture traps for decay prevention also reduces favorable nest sites for ants.
Adult carpenter bees resemble bumble bees. Both have yellow hair over most of their black bodies, but the carpenter bee differs by having a hairless abdomen (Figure 27). The adult female bee bores a 3/8- to 1/2-inch round hole into wood, makes a right angle turn, and tunnels along the grain of the wood (Figure 28). Wood is not ingested, but discarded out the entrance hole. The tunnel is partitioned into cells, each containing a ball of pollen and nectar and egg. The offspring feed on this food until mature, and then all emerge through the hole made by the parent female. Young adults over winter until April or May, feed on nectar, mate, and often reuse the tunnel where they were reared to lay eggs. Reused tunnels may be several feet long. Repeated tunneling may weaken individual timbers or ruin moldings and trim work (Figure 29).
Figure 27 - Carpenter bee
photo by Terry Price |
Figure 28
photo from USDA Forest Service - Wood Products Insect Lab Archives |
Solitary wasps and bees place food and eggs in beetle exit holes in log walls and seal the hole with a “wall” of dirt (Figure 30). The offspring bores a small hole in the wall of dirt to come out, often causing powdered dirt to accumulate beneath the hole. This is sometimes mistaken for a beetle infestation. These insects do not harm wood; caulking beetle holes to prevent decay eliminates them.
Injecting recommended insecticides into nests and tunnels will control carpenter bees. Dust formulations often work best. Don’t seal treated bee holes until the bees are allowed to move freely over the insecticide. The holes can be plugged in the fall with a wooden dowel or silicon sealer. Preventing nesting by bees in logs is very difficult, even pressure-treated wood is sometimes attacked. Painting frequently attacked timber will sometimes discourage bees. Substituting pine facia boards with white oak worked for one homeowner in eliminating carpenter bee boring.
Figure 29 - Carpenter bees readily attack brick and eaves molding
photo by Bill Godfrey |
Figure 30
photo by Bill Godfrey |
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