Treating A Nest Inside A Wall Or Attic

What a Wall Void and Attic Nest Treatment Is and When It Is the Right Call

A wall void nest starts small. A queen finds a gap, often at a soffit, a vent or an unsealed utility penetration, and builds inside the cavity behind it. By midsummer the workers are flying in and out constantly, and by late summer a European hornet colony can be several hundred insects and a yellow jacket colony several thousand. European hornets are very large and build very quickly; homeowners here sometimes call them Japanese hornets. Because of their size the sting is very painful, which is one reason this work belongs to a technician with protective gear.

We start by finding the actual entry point, which is not always where the insects are most visible, and by locating the nest inside the cavity as closely as we can from the traffic pattern, by listening and, where useful, by checking the attic. The product is then applied into the void through the entry opening so it reaches the nest and the insects moving through the cavity. A dust or an aerosol made for voids is typical, because it travels through the cavity rather than sitting where it lands. The technician then leaves the opening as it is.

Sealing the hole is the last step, done only after the traffic has stopped. Foragers out in the field need to come home through the treated opening to contact the product. A colony that is sealed in alive looks for another exit, and a hornet or yellow jacket that emerges from a light fixture or a chewed spot in a ceiling is a much harder problem than one entering the wall from outside.

Expect activity at the opening to drop over a day or two, and expect us to come back and check before anything is closed. Where the nest can be reached in an attic it is removed once quiet. Inside a closed wall it usually stays where it is, and the dead colony dries out without causing a problem. Sealing the entry afterward is part of the work, and we look for the similar gaps nearby that next year's queen would use.