Why Can’t We Get Rid of Fungus Beetles?

By Chris Williams on December 9, 2016.

We have an ongoing problem with what we were told are fungus beetles. We found dozens of them on the ceiling in a corner of the kitchen. We had an exterminator treat the area and my husband found a roof leak in the attic that had dripped onto that area. The leak has been repaired but now we’re starting to see beetles again! Any suggestions?  O. R., Tilton, NH

Fungus beetles are very tiny brown beetles that feed on mold growing on various surfaces. Sometimes the mold is barely visible. There are several species of fungus beetles but all require high moisture levels to survive. They can be seasonal and tend to be more of a problem indoors during seasons of high humidity outside. Drying out the site is the best way to control fungus beetles. I can think of a few possible reasons why fungus beetles are still a problem at your house.

(1) Some Beetles Might Have Survived the Treatment

It’s possible that what you’re seeing are beetles left over from the original infestation. Some larvae may have already pupated at the time of the treatment and were not affected by the insecticide. They have since emerged as adult fungus beetles — but if the moisture has been eliminated, they should soon die from the drier conditions or from contact with insecticide residue remaining on surfaces.

(2) Moisture is Still Too High, Somewhere

You might have missed a moisture site that is still keeping humidity high enough to grow mold and keep the beetle population going (see Fungus Beetles Mean Things Are Too Damp). The bad news is that the moisture might be hidden, for example, from a leaky pipe hidden in a wall void. Also, unless you physically dried out the damp ceiling site with heat or fans, it could take some time for it to dry, so mold could still be present for a while. Use a moisture meter to check various spots around the infested area and see if you can find an area of higher moisture.

(3) The Identification Might Be Incorrect

Your pests might not be fungus beetles after all. You don’t say who identified them, but try to get another opinion from an expert. Tiny brown beetles all look very much alike, even to the trained eye. Because of the location of the infestation, it’s possible that the beetles are stored food pests instead, perhaps flour beetles or sawtoothed grain beetles. In fact, if the beetles in question are foreign grain beetles, they actually feed on fungus and can be found in foods or any other site with mold (see The Foreign Grain Beetle is Actually a Mold Pest).

Give Colonial Pest a call today. Our technicians love to solve pest mysteries. We can determine exactly why you still have beetles and we can get rid of them for good — guaranteed.

Photo Credit : By CSIRO, CC BY 3.0, Link



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