Question
QUESTION: We have just finished cutting the joinery on two Eastern White Pine timberframes here in Arlington Massachusetts and have discovered what we believe to be Sawyer Beetle holes in several parts of the frame.  We were actually able to pull out a live beetle in the grub stage from a 1/2" long hole he was crawling in.  My question is: When these grubs become the adult beetle, will they repeat a cycle of boring and damaging my frames or will they go loking for Pine trees? Any advise or suggestions you have on how to deal with this problem would be appreciated. Thank you.

ANSWER: Pine sawyers do not bore into the wood but feed just under the bark. I think what you are seeing is a powderpost beetle.

Most commonly, infestations of Anobiid powderpost beetles are found in structural timbers made of softwood, such as beams, sills, joists, studs, subflooring, and plywood. In addition, Anobiids will infest hardwood furniture, wall paneling, window and door molding, hardwood floors, and furniture. Woods such as maple, beech, poplar, and pine are especially susceptible to attack. They prefer to infest wood with high moisture content in poorly ventilated areas in crawl spaces of houses, utility rooms, and garages. More than likely these entered the wood as it was stacked and when you cut the frames you were able to see the larvae. They can re-infest wood but only if it has a higher than normal moisture content. Wood that is dry is not re-infested. So I do not think you would have a problem with the frames being attacked again.
To kill the larvae in the wood it would need to be dried. Small pieces can be placed in a microwave oven for about a minute and this will kill the larvae in the wood pieces assuming the pieces are small enough to fit in the oven.

---------- FOLLOW-UP ----------

QUESTION: We have done a fair bit of research and are convinced the critters we have in our frame is in fact the Sawyer Beetle, otherwise known as longhorn beetle.  Since we have one in captivity, we are sure of the species.  That being the case, could you respond again to my question regarding this animals life cycle and whether we can expect it as an adult to rebore and lay eggs and repeat a cycle of damage????
Perhaps if your expertise does not include the Sawyer, you could refer me to someone who is?

Thank you,
Steven


Answer
There are two types of beetles that bore into trees. Roundheaded and Flatheaded.

Beetles in the family Buprestidae, or flatheaded borers, are beautifully marked, metallic-colored beetles, varying greatly in size but usually somewhat flattened and boat-shaped. The wood- boring larvae are characterized by a hammer-headed shape produced by a flattened enlargement of the body region behind the head.

Adult females lay eggs singly or in groups on the bark or in crevices in the bark or wood. The young borers (larvae) mine the inner bark or wood. The galleries of the larvae are flattened, usually oval in cross section, and winding, gradually enlarging as the larva increases in size. These larval mines are always tightly packed with fine sawdust arranged in arc-like layers. The adult beetles on emerging through the bark or the wood leave a characteristic oval or elliptical exit hole.

The flatheaded borers are of considerable importance in the forest. The greatest damage results from the larvae boring into the sapwood of recently felled logs. The larvae will attack and feed on a variety of softwoods and hardwoods.

Roundheaded borers are elongate, cylindrical, and have large gnawing mandibles. The name roundheaded borer refers to the enlarged thorax directly behind the head. They are sometimes mottled or banded with white or gray. Adult roundheaded borers are often referred to as longhorned beetles because of their long and distinctive 11-segmented antennae, often longer than the beetle's body. The thorax and wing covers on some species bear small, stout spines.

Most of the hundreds of species of roundheaded borers are found in weakened, dying, and dead trees. In addition, they feed on felled trees, stumps, and cut firewood. Roundheaded borers feed under the bark and in the sapwood of trees. Adults often emerge from firewood that is brought into the house and may cause concern. They will not infest structural wood and are a nuisance only.

There are several species of longhorned wood borers in the genus Monochamus which attack and breed in various conifers. The larvae (roundheaded wood borers) are commonly known as sawyers or pine sawyers. The name sawyer has been used to describe the larvae because they frequently make loud noises while they are feeding.

Heat-treating unseasoned lumber to a core temperature of 136o F for 30 minutes eradicates the insects in the wood.