European Hornet

The eyes of V. crabro are deeply indented and shaped like a "C". Its wings are reddish-orange, while the petiolate abdomen is striped with brown and yellow. It has hair on the thorax and abdomen, although the European hornet is not as hairy as most bees. Due to this coloration and abdomen pattern, V. crabro is often mistaken for the Asian giant hornet. Typical mass size for the European Hornet is 477.5±59.9 mg. Workers average around 25 mm (1.0 in) in length, while the larger queens can reach up to 35 mm (1+3⁄8 in). This is significantly larger than most common wasps (such as Vespula vulgaris), but smaller than the Asian giant hornet. Females are typically larger than males in both size and mass. However, male abdomens have seven segments, whereas female abdomens have six. There is a cerebral ganglion, two thoracic ganglia, and five abdominal ganglia. Only females possess a stinger, which is a modified egg laying device (ovipositor); males cannot sting. The antennae of males are slightly longer, with 13 segments, compared to 12 segments in females.

The European hornet V. crabro originated in Eurasia. Nests historically ranged from Japan to the United Kingdom. However, Saussure reported that V. crabro was introduced to North America in the mid-19th century, where it is now well established. In 2010, they were found as far south as Guatemala. The few nests in Guatemala were thought to be recent, accidental introductions, as they were the first to be documented.

V. crabro prefers to build nests in dark places, usually hollow tree trunks. After the site has been chosen, the queen lays eggs in the combs inside the nest. The workers dispose of any eggs that are not laid by their queen; this behavior is called worker policing. Based on laboratory data, the average rate of egg-laying is 2.31 eggs per day. However, in this same nest, cell construction rate was only 1.63 cells per day. V. crabro colonies seasonally change strategies of obtaining food for both the larvae and adults. In April, when the queen normally lays her eggs, the workers actively go out and forage. Later, typically around the fall season, the foraging workers switch to scavengers. Instead of putting forth the effort to catch food sources, the workers try to take what is more easily available. For example, European hornets have been seen hovering around garbage cans and picnic areas in the fall.