Renovation Brings Fungus Beetle Problem

By Chris Williams on March 26, 2014.
New England fungus beetle


We renovated our home and added a master bedroom suite just two months ago. Now we have all kinds of bugs flying around inside in that new wing. They look like tiny beetles. I don’t think they’re coming in from outside but I don’t know what they could be feeding on in that bedroom. I find them around the windows mostly. Any ideas?


This problem really requires a professional inspection to determine the source of your pests. In any other area of a house, stored food pests would be a consideration, but unless you have food hidden away in the bedroom, that’s not likely. If there was a dead mouse or other animal in a wall void, they could be dermestid beetles feeding on the carcass. But since we are talking about new construction, I’m going to wager a guess of fungus beetles that have been living behind the walls.

Tiny, dark fungus beetles are fairly common in new homes (or renovations) where building materials are still “green” or damp. Green lumber, drywall, plaster, wallpaper—all of these new building materials can have a high moisture level for some time. When wall and ceiling voids are closed in, moisture can remain inside the walls for months, and mold can grow on surfaces. Fungus beetles are more of a problem in humid regions and during times of the year when relative humidity is high.

There are several different types of fungus beetles that can be found in these situations. All are tiny (about 1/8 inch long) and dark. They feed on the thin layer of fungus growing on wallboard, lumber, or other materials. Often you can’t even see the mold on the surface so people think that the beetles are feeding on the wood or wallboard itself. These little beetles will also leave their voids and fly to lights or windows.

Dry Out the Area to Get Rid of Fungus Beetles

If your pests are indeed fungus beetles, an exterminator can treat the bedroom area but you probably won’t be completely rid of the beetles until things gradually dry out. When the moisture level drops, the mold will die, and the beetles will die or leave the area. You can speed up the drying process by using fans and dehumidifiers in that room, by running the furnace, installing vents or even opening up the wall voids if you can determine that is the source of the problem.

Photo credit: Dendroica cerulea / Foter / CC BY



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