The European hornet is among the largest of hornets. Though helpful since it feeds upon live insects including grasshoppers, caterpillars, flies and even yellowjackets, the European hornet is able to fly during the night and can even sting repeatedly in defense of the nest entrance.
In certain cases it builds its nest too close to dwellings, hunts in human-use areas, becomes attracted to lights, strips bark from ornamental plants, consumes tree fruits, and raids domestic Honey Bee hives.
How you can Recognize European Hornets
European hornets are large, up to 1-1/4 inches long with the head and thorax (middle part) red-brown. The belly (rear part) is black with yellow markings. Occasionally they’re confused with the baldfaced hornet, which has a black head, thorax and abdomen with white markings.
European Hornets – Life Cycle and Habits
European hornets typically are a woodland species which builds its nests in hollow trees. Sometimes, nests are found in attics, hollow walls, bird houses, barns, and abandoned bee hives in unprotected places. Nests are covered with a thick, brown envelope (paper-like) composed of coarse, decayed wood fibers which are quite fragile. These nests might have more than one entrance.
A mature colony will contain 1,500 to 3,000 cells in six to nine combs. The lower two to four combs contain queen cells. There usually are 200 to 400 workers during the summit population. The life cycle is similar to yellowjackets, with overwintering queens preparing nesting sites in the spring (usually in May). Queens make the nest and lay some eggs.
Currently, as the first generation is growing, the queen cares for the larvae by hunting food and enlarging the nest. After larvae reach adulthood, they take over housekeeping, nest expansion, hunting, and caring for the new larvae. The queen lays eggs for the remainder of the year.
As the nest keeps growing in size and number of workers throughout the summertime and early autumn, output of sexually active males and females begins to build up in July. Mating occurs and inseminated queens spend winter in safeguarded places until next early spring. Following a heavy freeze in November, the nesting individuals die out.
During the summer, these hornets can fly at night and are often attracted to light. They occasionally fly into the beam of a flashlight (bumping into the cover glass) or appear at porch party lights, lantern lights at campsites, etc. Occasionally, some fly against windows, causing humans to believe they are attempting to get inside to attack them.
Workers girdle twigs and branches of numerous trees and shrubs including lilac, birch, ash, horse chestnut, dogwood, syringa, dahlia, rhododendron and boxwood. These plants are sometime killed. Much of girdling is done for sap collection, not fiber.
Various property owner problems involve nesting too near human-occupied structures; presence around picnic grounds and yards; consuming ripe as well as near-ripe fruit like for example apples, puncturing an opening and hollowing out the fruit; and raiding domestic Honey Bee hives. However, they aren’t as aggressive as yellowjacket wasps.
