What does wood taste like? If you asked your local insect population, some of them would tell you that certain species of wood are delicious. Unfortunately for us, wood with little tunnels or holes in it is usually not very pretty looking to us humans and may not be as strong.

It is a constant battle to keep insects away from wood, especially from green wood both logs or lumber. Once the wood is quite dry, almost all insect activity ceases, except for three insects: termites, powderpost beetles and old house borers. So, insects that were in the log or were present during drying are no longer able to eat kiln-dried wood and are no longer a problem in dry wood, except for the holes that they leave.

Should there ever be a question about insects in work that you have made, contact your local county extension office for assistance. They can provide, perhaps through contacts with the state university, identification and appropriate remedial options.

Powderpost Beetles

These very troublesome beetles are one of the few insects that like drier wood. The anobiid powderpost beetle, which makes holes that are 1/8 inch in diameter in the sapwood of softwoods and hardwoods, prefers wood between 13 to 30 percent MC. The lyctid powderpost beetle, which makes 1/32 to 1/16 inch diameter holes in grainy hardwoods like oak and ash, is active in wood between 8 to 28 percent MC. It is the lyctid powderpost beetle that is most worrisome and one that causes many dollars in damage. Such damage is usually discovered by the homeowner.

When these beetles begin to exit the wood in the springtime, they push the dust, called frass, that is packed into the holes out ahead of themselves. The result is that piles of powdered frass are often noted around and under the holes.

Once the insect lays eggs in the wood, it may be as long as two years before the beetle exits and the frass is noted. This means that lumber not fully dried is subject to infestation; yet the damage or exit hole frass may not be seen for months; that is, when the piece is in service and not when it is first manufactured. Of course, during this time between manufacturing and use, the insect is active inside the wood.

Control is achieved by kiln drying over 130 degrees F, by keeping the wood under 8 percent MC, or by commercial fumigation (very expensive and dangerous). Most infestations develop when uninfected lumber is stored next to infested wood (especially lumber and plywood), so careful, separate storage, especially when handling wood from foreign countries (which often has infestations), is advisable. It is next to impossible for the insect to infect wood that has a smooth finish, like varnish, on it.

Termites (Subterranean)

This insect is common in most warmer climates in North America. It riddles dry wood (10 to 30 percent MC, roughly) with tunnels. It will infect almost any species of wood grown in North America; some tropical woods have natural resistance. Often, as the termites do not like light, they are not noted for several years after infestation, as the exterior appearance of the wood has no indications of their presence. However, as they need a source of water, often they will make mud-like tunnels on the outside of wood connecting the wood and water source. Look for them around damp plumbing pipes or other damp areas. Construction techniquestermite shields, treated wood, building site clean-up and moisture prevention are very effective. Commercial fumigation of a structure or treating the surrounding soil are the only effective control measures once termites are found. (As these insects do not eat their way through wood rapidly, homeowners with an infestation should take time to obtain several inspections and bids to assure a reasonable treatment program for their home.)

There is also a termite that flies between the wood and the water. These are seen mostly in tropical climates.

Old House Borer

This insect actually infects the sapwood of pine (and rarely spruce), making oval holes that are up to 1/4 inch in the long dimension. They prefer new wood, so their name is actually not very descriptive. The inside of their tunnels, which are typically just under the wood's surface, are rippled.

When the insects are chewing wood, their jaws will snap shut on each bite. If it is a quiet time, these small "snaps" or "clicks" can be heard.

It can take three to five years for a life cycle to occur. Then when the insects leave the wood to breed, male and female must find each other which, unless the infestation is large, is tough. So, it is not uncommon to find that they die out naturally. Fumigation is the preferred control for serious infestations. For small, localized infestations, removing the infected section of wood is appropriate. Although kiln drying above 130 degrees F will kill the insect and eggs, unless the wood is kept very dry (under 10 percent MC), there is a slight risk of infestation, especially if stored or in contact with other infested wood.

Carpenter bees

Carpenter bees look like bumble bees, except bumble bees have yellow stomach hairs. These insects do inhabit dry wood, but they only make tunnels so they can nest in the wood. They do not eat the wood. They are found outside, so seldom would be a problem with wood products, other than construction materials. In fact, as they do not like painted wood, they are seldom a problem in most homes and offices. As they return to the same nest year after year, control is achieved by spraying their holes with an approved insecticide when they are active and then plugging the hole with a wooden dowel.

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