TIM LOCKLEY: Old house borers find newer houses tasty
The old house borer (Hylotrupes bajulus) arrived in North America about 150 years ago, probably from Africa. It is found in the U.S. from Maine to Florida and west to Texas. Recently, the Oregon Department of Agriculture identified one of these beetles in a house, so they may have spread throughout the country by now.
Its name, old house borer, might be somewhat misleading. Initially, it was found in the untreated wooden houses that predominated the country in the late 1800s and early 1900s. These days, most of the infestations are found in recent constructions (four to seven years old).
Infestations of H. bajulus aren't noticed until the adults emerge, leaving behind holes around the width of a pencil. The adult beetles are 1.5 to 2.5 centimeters in length (5/8 inch to 1 inch). They are gray to brownish-black to black and have antennae that are half the length of the body (they belong to the family Cerambycidae, the long-horned beetles).
Close observation will show the presence of fine gray hairs on the thorax. Patches of gray hairs can be seen on the elytra (wing covers) as irregular lateral bands. The larvae, which are seldom seen, are cream colored and can be up to 3 centimeters in length. The tunnels the larvae make are packed with a fine powder made up of the beetles' fecal material (frass). The first two or so years after they start boring into wood, the larvae are too small to be noticed. When they get older and larger, you might be able to hear the larvae gnawing the wood. The act of chewing with their hard, sharp jaws creates a sound similar to someone clicking their finger nails.
Most infestations begin on felled logs or in wood stored in lumber yards. The female lays 40 to 50 eggs over a five-day period, but only on soft wood that is less than 10 years old. The eggs hatch in a little over a week and the young beetles bore into the sapwood. Under natural conditions, old house borers can reach maturity in two to three years. However, under the very dry conditions that exist within our buildings, development can take up to 15 years. During the winter months, feeding can subside markedly. Once emerged, the adults only live for a week or two.
Determining the extent of the infestation can be difficult. It may require the use of a listening device such as a stethoscope and a lot of patience. Controlling old house borers usually requires hiring a professional. If the infestation is limited to only a few boards, they can be removed and replaced with treated wood.
If the infestation is extensive you can: 1. fumigate; 2. remove any varnish or wax from the wood, sand and apply a borate or; 3. remove and replace all of the wood within the area infested and replace with treated wood. Since old house borers can reinvest the wood from which they emerged, their ability to cause extensive damage over time should not be taken lightly.
Tim Lockley, a specialist in entomology, is retired from a 30-year career as a research scientist for the U.S. Department of Agriculture. For answers to individual questions, please send a stamped, self-addressed envelope to Tim Lockley, c/o Sun Herald, P.O. Box 4567, Biloxi MS 39535.
This story was originally published January 7, 2016 at 5:36 PM with the headline "TIM LOCKLEY: Old house borers find newer houses tasty ."