Genus: Vespa Linnaeus, 1758
Species: Vespa crabro Linnaeus, 1758
Common name: European hornet
Vespa crabro is a large eusocial paper wasp native to Europe. It is also the only species of Vespa established in North America. It was introduced into the southeastern United States in the 1800’s by European settlers. V. crabro are mainly carnivorous and hunt large insects such as beetles, large moths, dragonflies, mantises, and other wasps to feed their young. However, they also girdle twigs to drink sap or feed on fallen fruit (Bromley 1931).
Although native to the Palearctic Region, Vespa crabro was introduced into New York in the 1800s and is now widespread in the eastern United States, extending as far west as the Mississippi River and as far south as New Orleans (Akre et al. 1981). Scattered populations probably also exist in southern Ontario and Quebec. Specimens of V. crabro were found in a museum collection in Guatemala, but there is no evidence they have become established (Smith-Pardo et al. 2020).
Distribution map of Vespa crabro by GBIF: https://www.gbif.org/species/1311527
All subspecies are now considered informal regional color forms (Carpenter and Kojima 1997).
Workers of Vespa crabro prey on a diversity of insects, such as grasshoppers, flies, and honey bees. They bring prey back to the nest as food for their larvae. Adults mainly feed on sap and nectar. As part of this sap-feeding behavior, they may girdle twigs and branches of deciduous trees and shrubs, such as lilac, birch, ash, chestnut, dogwood, dahlia, rhododendron, and boxwood. This behavior may lead to the death of the plants they girdle. Vespa crabro is a pest of honey bees in Japan and Europe (Akre et al. 1981).
New queens emerge from overwintering in the spring and search for a suitable site to build a nest. Hornet nests are built from chewed wood pulp mixed with saliva. In Europe, V. crabro typically build their nests above ground in hollow trees but will also use thatched roofs, barns, attics, hollow walls of houses, and abandoned beehives. There have even been a few subterranean nests reported. The nests of V. crabro can be distinguished from the other more common gray nests of Dolichovespula maculata by their nest’s browner color (Akre et al. 1981).
Early on, eggs are laid in individual paper cells, which develop into workers. When 5–10 workers have emerged, they take over the care of the nest, and the queen spends the remainder of her life egg-laying. The workers forage for insects to bring back to the nest to feed the brood. Workers feed on sugary foods, such as sap and nectar, but they also feed on a sugary liquid excreted by the hornet larvae.
The nest reaches its maximum size by mid-September. By then there will be 200–400 workers in the nest. In this period, the queen begins laying eggs that develop into males and new queens. This signals the end of her life, and she dies shortly afterwards. The new queens and males mate during a ‘nuptial flight’. Once mated the new queens seek out suitable places in which to overwinter, and the males die.
A native of Europe, this species is considered invasive in the United States, China, Iran, Japan, and Guatemala.