Help! I have a problem with carpenter bees making their nests in the...

Asked April 24, 2017, 2:37 PM EDT

Help! I have a problem with carpenter bees making their nests in the insulation of my house. The wood siding sticks out from the foundation about 1/2 ", the width of the underlayment (an insulation material) and the bees are drilling their holes up into that, leaving the telltale sign of a sawdust looking pile. We saw evidence of some last year and called ABEL pest control. He said the damage was already done for the year and suggested we spray the surface where the bees were going in early in the spring this year before they became active, with Thomson Water Seal. He thought that would deter them. We followed his advice, spraying 2 times in early spring of this year. Now the bees have multiplied to the point of sawdust piles along half of the perimeter of the house. What can I do? I am very reluctant to use pesticides because I know bees are pollinators and I don't like exposure to chemicals myself. Is there any way to stop these bees from destroying the exterior walls of my house? I have researched the problem online and find many contradictions. One problem is that the bees are laying their eggs in the insulation, and I fear that trapping them will cause them to bore into the interior of my house when they hatch out. Is this true? That would be worse! Please include the TIMING of treatment in the lifecycle of the bees with any advice. Thank you!

Greene County Ohio

1 Response

The most effective eradication method is a dust insecticide. If you decide to go this route take precautions and apply in the spring, mid summer and again in fall before closing up the holes left by the bees. There are a few options to help deter the bees if you do not want to use the insecticide. You can try to continue to plug the holes left so that nesting bees do not seek shelter in them. I know you tried the Thompson's water seal but try applying a different stain or varnish, as the bees generally go for untreated wood. I also included a link to a homemade trap that may be an alternative to pesticides.