Anobiid Beetles

Anobiid beetles are small- 1/8” or less. They require relatively wet wood preferring moisture levels starting at about 13% and going up to FSP of about 30%. For this reason they tend to be more common in wood close to soil and areas with poor ventilation or drainage.

Anobiid Beetle 

Life Cycle

1. Around late August, females lay 10 – 30 eggs, singly or in small groups, in natural depressions on log surfaces.
2. Upon hatching 3 weeks later, larvae bore directly into wood (or often leave for more suitable feeding grounds). Anobiids may spend 4 - 5 years in the larval form, feeding on wood.
3.  In late spring or early summer, mature larvae move to within a few millimeters of the log surface to pupate and morph into adults.
4. Adult beetles chew a round exit hole, 1/16” to 1/8” in diameter, and emerge during mid-summer.

Inspection

One of the challenges when dealing with an anobiid beetle infestation is determining whether insects are still present and feeding in the wood.

Fine sawdust or frass coming out of small holes in the wood is usually the first sign of the presence of anobiid beetles.

A good method is to cover a six-inch area of suspect wood with a layer of masking tape in early to late spring. If, after a couple of weeks there are no small holes in the masking tape, chances are good that the infestation is old and inactive.

Inspectors may try resonance testing (tapping) to test logs suspected of containing galleries. Resistance drilling may produce results.

Courtesy of Permachink Inc.

Anobiid emergence holes (both photos above)