European Hornet Control for Walls and Attics

European Hornet Control

European hornets are the largest hornets in southern Virginia and northern North Carolina. Workers are about an inch long and queens are larger. They are brown and yellow with a reddish brown head, and because of their size homeowners often call them Japanese hornets or giant hornets. They are neither. They are a European species that has been in the eastern United States for well over a century, and they are the only true hornet found in North America.

They nest in enclosed spaces: hollow trees, wall voids, attics, barns and outbuildings. Unlike bald faced hornets, they rarely hang a nest out in the open. The nest is built from chewed wood fiber and looks like tan or brown paper. A colony can hold several hundred workers by late summer. European hornets also fly at night and are drawn to porch lights and lit windows, which is often the first time a homeowner notices them.

What sets them apart is how fast a colony builds once it finds a way in. We have seen a nest built in an attic where the hornets chewed through the ceiling drywall and hung the nest down into a bedroom, all within about two weeks of getting into the house. A gap at a soffit, a missing vent screen or an opening around a chimney is all they need.

The sting is very painful because of the size of the insect and the amount of venom it carries. European hornets are not aggressive away from the nest, and they will usually leave you alone in the yard. Close to the nest they defend it, and a nest inside a wall or attic puts that defended zone inside the house.

We locate the nest first. Watching the flight line at dusk and listening at walls and ceilings usually narrows it down. The nest is then treated in the cavity where it sits, so the treatment reaches the colony rather than the few hornets at the entrance. We do not seal the opening until activity has stopped, because a sealed colony chews its way out somewhere else. Once the colony is no longer active, the nest material can be removed where it is accessible and the entry point closed so the void is not reused.

European hornet colonies die off with the first hard frosts, and only new queens survive the winter. Finding and closing the gaps they used is the part of the work that matters for next year, and it is part of the free inspection.