Exterminating Insects in Furniture

A table built from old wood previously stored in a barn now has "old house borers." The solutions are fumigation or heat. March 13, 2007

I am the owner of a custom furniture company. Several years ago I responded to a customer's request to build a harvest table with old and wide pine boards for the top. Last week I was in the customer's home and they directed my attention to this table. It had some type of insect (beetle with occasional snapping sound) in the old wood. What is the best and simplest method for dealing with this situation?

Forum Responses
(WOODnetWORK Forum)
From contributor H:
Have you actually seen one of these critters? Using old wide boards, this is what you sometimes get. The occasional snapping noise… Do they keep a stethoscope on the table? Is their hearing capable of echo location? :)

Could it be that the old wide boards are checking further as they acclimate to the home? If they are in fact beetles in the table, then remove it from the home before they find fresh meat. Strip it. Kiln dry the boards and rebuild it. Or just get more of the same old wide boards and kiln them first and build them a new one.

From contributor D:
Contact a pro exterminator. They can probably bag it and gas it. They do houses - one table shouldn't be too bad. If you had the means and the table could take it, a day at 120-150 degrees (f) might do it. But that would be kind of hard on a piece of furniture. But if it's already rustic/distressed, maybe no one would notice a new crack or two. Call bug guy first, though.

From contributor V:
Fumigation is the solution. This is a real problem with bringing in wood from the old barn and putting it in a house. The bugs wake up and have a nice controlled environment for their buffet.

In the urban legend/wood department, I once heard about an ash bed made by a woodworker for himself. He set it up in his bedroom and when he awoke the next morning, enjoying the fruits of his labors, he heard chewing sounds. He realized it was coming from the wood, started looking around and found sawdust on the floor under the headboard. Ash borers were eating his work, and dropping frass out of the bore holes.

Call a fumigator. The liability is a trickier question - the customer's if they specifically asked for or supplied this lumber, yours if you sold it to them, but there will be some gray area.

From contributor M:
We treat our old material with a product called Bora-Care. It is a spray-on solution that is basically just boric acid.

From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
This insect is called the old house borer. The snaps you hear are the sounds of its jaws snapping shut when it takes a bite. (No fooling!)

Forget about a surface treatment such as Bora Care, as that only treats the surface and this insect is inside the wood and may not exit for a long time. Further, anything you use for a table that may have food on it must be 100% safe for food and people.

I suggest you rent a small trailer, put the table in it and then run the temperature up to 130 F (if you can do this without burning the place down). You can add a few wet towels inside to avoid getting it too dry. But even if it is dry, it will not affect the wood too much as you only need to be at this temperature for a few hours (temperature is inside the wood). The heat may melt the adhesive, however. It may melt a wax finish too. In this case, just have the piece fumigated.

Note that the insect does not easily spread. If it leaves the piece, then Ma and Pa have to hook up, breed and then find a place to lay eggs. There are probably only a few beetles in the wood in the first place, so the chances of two getting together is so slight. However, right now they are tunneling through the wood. Incidentally, they only go for softwoods and not the hardwood species.

From contributor S:
Borates are fine, provided you give them the right conditions to permeate right into the wood. The best way is to spray to saturation, then wrap the timber in tarpaulins. After a couple of days, spray again and re-wrap. After about 2 weeks, the borate will have permeated well into the timber, carried in by the moisture of the spray treatment that is being retained by the tarps.

From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
Contributor S is indeed correct about borates diffusing into wood if the wood is soaked in the borates. However, in this case we are dealing with a table that is already dry and finished and in use. Soaking a table just does not seem like a reasonable activity, and such action will likely destroy the finish and the glue joints. A surface treatment only will not diffuse into the wood.

Incidentally, the borates will not permeate into a species such as white oak or black locust and others. I am also not sure if it will permeate through an existing finish. Although it does not apply in this case, borates will leach out of the wood if the wood is exposed in a wet condition, such as direct rainfall.

From contributor T:
Doc, he says that the table was built several years ago (I am assuming here). Do you think the bugs were in the wood all along or that they just found it recently and started eating?

From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
We cannot be 100% certain that the insects were in the lumber before the table was built, but it is likely they were. As mentioned, if the insects were in the home in other softwood items (2x material), they would have trouble spreading. If the table were stored in a barn for a long time before it went into the house, it is possible that the insects entered that way. But it is far more likely that the old lumber was infected when the table was made.

From contributor E:
My father in law is an exterminator and he claims even though a lot of companies do such bugs as powder post beetles, wood borers, etc., the chemical used doesn't do any good unless the bug comes out of the wood to eat, such as carpenter ants. Most fogs and sprays will not penetrate the wood enough to be effective. The best way is use heat, just as the doc suggested.