Anobiid Beetles
Order:
Coleoptera
Family: Anobiidae
Scientific Name:
Euvrilletta peltata
(Harris), formerly
Xyletinus peltatus (Harris)
Euvrilletta peltata is commonly encountered in structural timbers and ornamental wooden pieces that have aged 10 or more years. The Anobiid beetle is responsible for financial losses due to structural as well as cosmetic damage resulting from the boring activity of developing larvae. Crawl space and basement timbers in the southeastern United States often exhibit signs of this beetle’s activity. Although infestations are mainly observed in softwoods (e.g., southern yellow pine), they are also found in hardwoods (e.g., yellow poplar).
Biology and Habits
Generally, the life cycle of an Anobiid beetle is two to three years (range of one to five years) in favorable woods and under favorable conditions. The nutrients in wood, temperature extremes and wood moisture content greatly influence the developmental period of larvae.
The larvae are cream-colored and lightly curved in shape. The body is lightly covered with hairs, and three pairs of legs protrude from the anterior underside. The developing larvae, the destructive life stage of these beetles, excavate tunnels as they feed, preferring the sapwood portion. These galleries become packed with frass (fecal pellets and wood fragments). Upon reaching maturity, the larvae move near the surface of the wood and transform into a non-feeding pupae. The pupal stage lasts about two weeks.
After pupation, adult beetles (about ¼-inch long) emerge from the wood through round exit holes 1/8-inch in diameter. Coloration varies from red to blackish-brown. The head is bent underneath the pronotum, and the antennae are composed of nine serrated segments. The sides of the pronotum are distinctively rounded and many fine, faintly visible hairs cover the body.
The adults are seldom seen by inspectors since they are mostly nocturnal, short-lived (two to four weeks), and emerge during a four- to six-week period (usually from April to July). Newly emerged adults mate, and fertile females then deposit their eggs in cracks and crevices of seasoned woods. Upon hatching, first instar larvae bore into the wood, renewing the life cycle.
Control
Infestations are usually discovered by signs of beetle activity. Infested woods exhibit small round exit holes or galleries that contain powdery frass. The frass can be pushed out of damaged woods during larval feeding or from tapping the wood with a screwdriver. Rarely are the adults or larvae seen during routine inspections. The inspector must be able to determine if the damaged wood contains signs of an active infestation or a previous one. Keep in mind that the number of exit holes does not necessarily indicate the degree of activity. Infestations are known to die out due to natural causes such as parasitism.
Once currently infested woods are identified, surface applications or wood injections with residual formulations can be used to reduce or eliminate existing populations. Fumigations with insecticidal gases will also provide good control results. But remember, when selecting any pesticide, always consult labeling prior to usage.
Various non-chemical control techniques have become popular in recent years. Decreasing the wood’s moisture content below 13 percent during the months of adult emergence will kill newly hatched larvae. However, additional controls may be needed to control adults or mature larvae still in the wood. Populations subjected to electrical currents or hot and cold extremes have been eliminated from accessible structural beams or smaller pieces of wood. Another option is to remove infested wood, if the infestation is localized.
(Courtesy of the National Pest Control Association.)