European Hornet (Vespa crabro): Facts, Nests and Behavior

What does a European hornet look like?

The European hornet has the classic wasp shape, with a narrow waist, two pairs of wings and a smooth, shiny body, but its colors are warmer than those of a common wasp. The head and thorax are dark brown to black with reddish-brown markings, and the face is yellow. The abdomen is yellow with brown or black bands and spots, and the front of the first segment behind the waist is reddish-brown. The legs and wings have an orange-brown tint.

True hornets can be recognized by the broad top of the head behind the eyes, called the vertex, which is much wider than in yellowjackets. Each compound eye has a deep C-shaped notch around the base of the antenna, and three small simple eyes, called ocelli, sit on top of the head.

Coloring varies across the huge range. In central Europe most hornets have a reddish forehead and reddish marks on the thorax, northern European hornets are often darker, and some English hornets have a mostly yellow head. These color forms were once named as subspecies, but a 2020 revision of the genus treats them as informal regional forms.

Males have slightly longer antennae than females, with 13 segments instead of 12, and seven visible abdominal segments instead of six. Only females can sting, because the stinger is a modified egg-laying tube, so males are harmless.

How big are European hornets?

European hornets are big for wasps, and queens are the largest members of the colony.

A typical adult weighs about half a gram (0.02 oz). A large queen is roughly twice as long as a common wasp worker, which measures about 12–17 mm (0.5–0.7 in), so a hornet looks impressive when it flies past.

Even so, the European hornet is only middle-sized within its genus. About 22 species of true hornets are recognized, most of them in tropical Asia, and the largest is the northern giant hornet of East Asia, whose queens can exceed 5 cm (2 in).

Where do European hornets live?

The European hornet has one of the largest ranges of any hornet. It lives across temperate Europe and Asia, from the Atlantic coast east through Russia and southern Siberia to China, Korea and Japan. In the north it reaches southern Sweden and the far south of Norway, but it has never been found north of about 63°N. In the south it reaches the Mediterranean region, where it shares some areas with the Oriental hornet.

It was introduced to eastern North America in the mid-1800s, probably around 1840 to 1860, and now lives across much of the eastern United States and in southern Ontario and Quebec. For most of that time it was the continent’s only true hornet. It has never become established in western North America, although nests have been recorded as far south as Guatemala.

Its favorite habitat is deciduous or mixed woodland with old trees, especially oaks, plus parks, orchards, farmland and leafy villages. What it really needs is a dark, dry cavity for its nest. Hollow trees are the natural choice, but hornets also use bird boxes, attics, sheds, wall cavities and chimneys.

What do European hornets eat?

Adult hornets and their larvae eat very different food. The adults run mainly on sugar. They drink tree sap, often stripping the bark from twigs of ash, lilac or birch to make it flow, and they feed on ripe and fallen fruit. They rarely visit flowers for nectar, and they also drink a sugary liquid that the larvae release when workers feed them.

The larvae need protein, so workers hunt insects for them. Prey includes flies, wasps such as common wasps and yellowjackets, honey bees, moths, caterpillars, grasshoppers, dragonflies and beetles. A hornet seizes prey with its legs and jaws, stings larger victims, then cuts off the wings and chews the body into a paste that it carries home. Hornets have even been seen stealing wrapped prey from spider webs.

A commonly cited estimate is that a large colony can catch around half a kilogram (1 lb) of insects on a busy summer day. Many of these insects are garden pests, so hornets help control flies and caterpillars. They do take some honey bees, but healthy bee colonies are rarely threatened, unlike the situation with the invasive Asian hornet.

Nests and colony life

A hornet nest is made of a fragile, papery material that the hornets produce by chewing rotten wood and mixing it with saliva. Because they often use soft decaying wood, the paper is brown, with orange and ocher bands. Inside are horizontal combs of six-sided cells that open downward, linked by short pillars. A large nest usually has about six combs, rarely as many as 15, and can reach about 60 cm (2 ft) long.

In Europe the outer envelope is often left open at the bottom, so droppings and food scraps fall out below the nest. A rove beetle, Velleius dilatatus, lives in this debris and feeds on scraps and dead hornets without harming the colony.

Colonies are small for social wasps. At the late-summer peak a nest usually holds a few hundred hornets at once, with up to about 700 workers in the biggest colonies, compared with several thousand in a common wasp nest. On hot days workers fan their wings at the entrance and bring in water to cool the brood.

Hornets have an orderly society. Workers can lay unfertilized eggs that would become males, but other workers find and destroy those eggs, a behavior called worker policing, so nearly all the young come from the queen. When the nest is threatened, guards release an alarm pheromone from their venom sacs that calls more defenders.

Life cycle: one queen, one summer

Only young, mated queens survive the winter. They hibernate alone for six to eight months in rotten wood, crevices or under bark. In central Europe they wake in April, in England often not until May, and each queen feeds on sap while she searches for a nest site.

The queen builds the first comb on her own, laying one egg in each cell and raising the larvae on insects she catches herself. Each egg hatches after about 5–8 days, the larva grows through five stages in about two weeks, and the pupa takes about two more weeks to become an adult. The first workers usually appear in June, after which the queen stays inside and only lays eggs.

From about August the colony starts raising new queens and males, and a successful nest can produce around 200 young queens. They mate in autumn, the males die by late October, and the old queen and remaining workers die as the weather cools. The empty nest is never reused, although hornets may nest in the same hollow tree year after year.

Do European hornets fly at night?

European hornets are unusual among social wasps because they keep flying in deep twilight and on warm nights. A study in Sweden found that they fly at light levels about 100 times dimmer than common wasps can manage, and they are often drawn to lit windows in late summer. They manage this without special night eyes, simply because their large size gives them large eyes. The details are in Do hornets fly at night?.

Are European hornets dangerous?

European hornets are much calmer than their size suggests. Away from the nest they usually avoid people, and they sting mainly when they are grabbed, trapped or stepped on, or when someone disturbs their nest. Colonies defend a zone of a few meters around the entrance, and vibration or repeated disturbance makes them more defensive.

The stinger is smooth, so a hornet can sting more than once. Hornet venom contains acetylcholine, which adds to the pain, but laboratory tests on mice suggest that, gram for gram, it is weaker than honey bee venom. As with any bee or wasp sting, the real danger is an allergic reaction. Anyone who has trouble breathing or swelling of the face or throat after a sting should seek emergency medical help immediately by calling 911 in the US, 112 in the EU or 999 in the UK. See Are European hornets aggressive? and the hornet vs wasp comparison.

Predators, threats and protection

Few animals tackle an adult hornet. Some birds catch them, large robber flies and hornets prey on each other, and the caterpillars of the bee moth can destroy weakened colonies by eating the comb and brood.

People have been the main threat. Fear has led to many nests being destroyed, and in Germany the species was long listed as rare and declining. It has become common again there since about the late 1970s, although the reasons for both the decline and the recovery are not fully understood. Since 1 January 1987 the European hornet has been specially protected in Germany, where fines for killing hornets or destroying an active nest can legally reach €50,000, and it is also protected in some Austrian states. The species has not been assessed for the IUCN Red List, so its global status is Not Evaluated.

Myths and facts

Myth: three hornet stings can kill a person and seven a horse. This old European saying has no basis. For a healthy adult who is not allergic, a few hornet stings are painful but not dangerous, and European hornet venom is no stronger than a bee’s.

Myth: hornets raid picnics like wasps. European hornets rarely come for jam or soft drinks. When they do visit outdoor tables in late summer, they are often hunting the wasps and flies feeding there.

Myth: every big hornet is a “murder hornet”. Many of the “murder hornet” sightings reported by worried people in the eastern United States in 2020 turned out to be European hornets or other large wasps. The northern giant hornet was found only in the Pacific Northwest.

Fact: several harmless insects imitate hornets. The hornet moth, a clearwing moth, and the hornet mimic hoverfly both copy the hornet’s colors to scare off predators, but neither can sting.