European hornets, when not in direct competition with humans for space and resources, are very beneficial by destroying harmful insect pests. Do not control these hornets unless necessary. They’re mainly a forest species, having few contacts with humans and present a minimal stinging hazard.
European Hornets – Nest Destruction
The best control measure is to destroy the nest. Be certain to work in pairs, wear protective clothing (with bee veil if possible) to cover the body and do the treatment after dark when most hornets are inside the nest. Use a flashlight (red cellophane over lens) while the other person applies the pesticide. Nests may be difficult to locate and out of reach high into a tree or structure.
There are literally hundreds of products labeled for wasp and hornet control. Use special wasp and hornet pressurized jet sprays containing synergized pyrethrins, resmethrin or carbamates and quickly volatilizing organic solvents. Sprays are emitted in a long, narrow stream 15 to 20 feet.
If the nest is hidden in a wall void, puff carbaryl (Sevin), pyrethrins (Drione), bendiocarb (Ficam) or deltamethrin (Delta Dust) powder or dust into the wall hole that is used as an entrance. Workers in time will carry the dust back to the queen, giving good kill. When hornet activity has ceased, remove and destroy the nest.
When the nest is a considerable distance from the entrance, spraying the opening may have little immediate effect. Don’t ever plug the wall entrance after treatment as hornets may chew out another entrance into the house.
European Hornets – Baits
Poisoned meat baits, which could work well with some yellowjackets, are not effective against European hornets, which prey almost exclusively on live insects. For the occasional indoor hornet, simply collect with a vacuum cleaner or kill with a fly swatter.
Normally it is best to use the services of a qualified specialist pest control operator who has the experience, equipment, training and pesticides to do the job correctly and efficiently.