European Hornet in Kentucky
ENTFACT-600: European Hornet in Kentucky | Download PDF
by Douglas Johnson & Lee Townsend, Extension Entomologists
University of Kentucky College of Agriculture
The European hornet is a large (1½-inch-long) brown and orange insect with dark wings. When away from the nest, it will only sting when threatened. However, these hornets will work together to defend their nest against anyone who comes too close. The pain is about the same as any wasp sting but hornets can sting repeatedly and attacks by many can be a very unpleasant, and potentially dangerous experience.
The European hornet is a woodland species that builds its large paper nest in natural cavities, especially in hollow trees. Often the nests are 6 feet or higher above the ground. Occasionally, the hornets will select a protected, undisturbed spot in a barn, attic, or wall void.
European hornets can cause problems in some specific situations:
- Nesting in a hollow yard tree, attic, or wall void.
- Coming to fruit trees in the fall, chewing into fruit for sugary juices.
- Stripping bark from shrubs can girdle and kill small branches.
- The hornets can fly at night and are attracted to lights so they may bang into windows to get to the source.
- Occasionally, hornets raid domestic honey bee hives.
An average hornet nest will have 200 to 400 workers by late summer and they can become aggressive if they feel threatened. Some of the insects act as nest guard; they will attack anyone who comes too close. If the nest is located where there is a threat of people being stung, especially if it is indoors, it is best to have it treated by a professional. An experienced pest control operator will have the equipment and knowledge to deal with it safely.
If the nest does not pose a danger, then it is best to leave it alone. European hornet nests do not survive the winter. The workers will die by late fall. A few fertile females will leave the nest to hide in sheltered places until spring. They will establish colonies in the spring. It is important to seal holes in structures that would allow wall voids and attics to be used again.
The life cycle of the European hornet is like that of paper wasps and yellowjackets. Each spring, queens come out of hiding and search for nesting sites. This typically happens in early May. The queen begins constructing the paper nest from chewed wood and saliva. She will lay eggs in the first cells of the nest. After they hatch, she will raise the first brood of hornets. They will be sterile females that will take over nest construction, brood care, and hunting so the queen can just lay eggs.
About mid-July, some males and fertile females will be produced. Mated females will overwinter and resume the cycle the following spring.
European hornets are predators that capture large insects – grasshoppers, flies, bees, etc., feed to their developing larvae in the nest. When food becomes scarce in the fall, they will search for sweets. Some will girdle twigs and branches of lilac, birch, and other species and collect the sap that bleeds from the wounds. Others may chew holes in tree fruit for liquids. It is difficult to prevent this from happening because the location of their colony may be impossible to find.
CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.
Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!