Round Headed Borer  (AKA Old House Borers & Longhorn beetles)

© 2008, Kenton Shepard

Adult Round Headed Borers are beetles 5/8 to 1 inch long. They infest both new and seasoned softwood, preferring the sapwood of Pine, Spruce and Fir. Despite the name, they attack both old and new homes.

Infestations are known from Maine south to Florida and west to Michigan to Texas. The westward range extends approximately to the Mississippi River.

Courtesy of Permachink Inc. 

Adult Old House Borer

Life Cycle

The life cycle of Round Headed Borers is heavily influenced by temperature, humidity and wood species. In South-eastern U.S., larvae require two to ten years to become fully grown and they can cause extensive damage to wood.

• The adult stage is short, lasting eight to sixteen days
• Eggs are laid in natural depressions on log surfaces and take 9 - 14 days to hatch. Larvae bore into the log immediately upon emerging from the egg.
• Larvae remain in logs anywhere from 3 - 14 years depending on local conditions. Under ideal conditions in many southern states, the larval stage may last 3 - 5  years, depending on local conditions. In more northern states, where humidity is low (as in some attics), an additional two to five years or more may be required to complete the life cycle.
• The pupal stage lasts two weeks, after which beetles emerge though a chewed oval emergence hole .

Re-infestation

Adults emerge June, July and August with females attracted to dry, seasoned wood where eggs are laid, re-infesting additional softwood, which they prefer. Because of the extended length of time they spend in the larval stage, boring and consuming wood, Round Headed Borers can do a great deal of damage.

Courtesy of Permachink Inc. 

Round Headed Borer larva 

Courtesy of Permachink Inc. 

Round Headed Borer damage

Infestation of Log Homes

Infestation and re-infestation of log homes is not uncommon. Eggs may have been deposited at a log yard or at the homesite. Log homes have a greater chance of suffering re-infestation than conventional homes because of the greater area of exposed wood and under certain conditions, a shorter feeding time for larvae.

Inspection

Infestation is difficult to detect during the early stages, since larvae are small, develop slowly and create no outward signs of damage. Inspectors should look for the following clues...

• At advanced stages, during the spring and summer, the “clicking” sound of larvae chewing can sometimes be heard.
• Frass in tunnels is loosely-packed.
• Flight exit holes, 1/8" to 3/8" are oval-shaped, slightly flattened, corresponding to the adult beetle shape. Exit holes may be surrounded by small piles of frass and tiny pellets.

Emergence hole, Round Headed Borer