Professionals and Amateurs Together

Old Barn Rafters


I recently bought a couple of old barn rafters, probably maple. They turned out to be full of worm holes which is fine by me as the wood is solid. My questions – Are there worms there now and if so, how do I kill them? Is the dust harmful? There is a lot of it. I am making a child’s bed with some of it. I would like to fill the holes and assorted cracks, etc. with dyed epoxy, accenting the negative as it were. Since the posts are turned the epoxy will have the chance to run downhill. I would prefer it not to. What do I do to make the epoxy stay in the holes and what do I dye it with? – Dave Frechette


DJ Delorie replies: When using epoxy to fill holes and gaps in wood, the best way is to fill the holes before turning or planing. As you fill each hole, cover the hole with tape to contain the epoxy. Plastic packing tape is probably best, as it’s wide, lightweight, and clear. To dye the epoxy, you can mix in any variety of dry pigment dyes (lamp black, powdered food dye, wood dust, ground pencil leads, etc).

Note that epoxy fumes are hazardous. Please take appropriate precautions.

Bruce Hamilton replies: There are many insects that make holes in wood, the termite and carpenter ant being the most notorious. The ones you are referring to are most likely a species of what is commonly known as the powder post beetle. The “dust” they leave behind is called fras and, as far as I know, it’s non-toxic. It is not the beetle that makes the holes but the larva. The larva feed on the wood, develop into a beetle, the beetle flies away to mate, the female lays her eggs in the wood and the cycle starts all over again.

Whether or not you have an active infestation takes a little detective work. You may see fras dust on the floor under the object. Sometime you can actually hear the lava eating! The larva have to have a certain level of moisture to survive. Fortunately for us, our homes are generally too dry in the winter and the larva dehydrate and die. This is the best and least toxic way to get rid of them.

Controlling the epoxy can be done in several ways. You’re going to have to experiment. I’d start by taping over the filled holes and cracks after I filled them. If you chill the epoxy it may stiffen sufficiently to prevent it from running. I think you can use just about any dye stain or pigment to color epoxy but I would do a test sample to verify that it will dry properly. You could also call the manufacturer for info as well.

Roy Noyes replies: This is a difficult question to answer fully. The holes that you refer to are undoubtedly Powder Post Beetle holes. The holes are due to the larvae which feed on the sugars in sap wood; the adults do very little damage. I would expect that even if you sealed up all the holes with epoxy, that there will be new holes appearing as the eggs inside the wood hatch and the adult beetles emerge. As far as I know, the dust is not poisonous, however the emerging beetles may attack other wood in your home.

I do not recommend using wood infested with powder post beetles and suggest that the best thing to do is burn it.

Control & Recommendations:

The following points should aid in discouraging powder post beetle infestations:

  1. The first thing to do is reduce the moisture content, through proper ventilation to less than 20%. Moisture meters can be used to determine the moisture level in the wood. Central heat, vapor barriers and good ventilation can help control moisture. Rough-cut lumber should be kiln-dried to kill all stages of the beetle. Reducing moisture, however, may not be enough to completely control powder post beetle infestations.
  2. Uninfested wood that is sanded and varnished will not normally be attacked by the adult beetles because they cannot find crevices in the wood surface into which they would deposit their eggs.
  3. Items of value should not be stored in out buildings such as barns and sheds. These buildings are often infested with wood-boring beetles.
  4. Infested furniture can be fumigated in a fumigation chamber. Only pest control operators licensed to do fumigations are permitted to purchase and use these materials.
  5. Surface sprays containing borates will prevent newly hatched larvae from entering the wood. However, this technique is not effective on wood, which has been varnished, waxed or otherwise sealed from attack by moisture.
  6. If practical, remove infested wood. If not, use residual borate insecticides.

Courtesy of the Do-It-Yourself web site.

Tags: Wood