European Hornet

Vespa crabro, commonly known as the European Hornet, is the only true hornet species found in North America. Adults are substantial, typically measuring 25–35 mm in length, characterized by a reddish-brown head and thorax, and a segmented abdomen featuring yellow and black stripes toward the posterior. The queens are slightly larger than workers, reaching up to 40 mm. Colonies are annual, initiated by an overwintered queen in spring, developing through larval and pupal stages within paper-like cells. A colony can grow to house 200–400 workers, with a lifespan for workers typically 4-6 weeks, and queens living up to a year. Optimal colony development occurs in temperate climates, with sensitivity to extreme heat or prolonged cold, requiring stable thermal conditions for brood rearing.

European Hornets are crepuscular and nocturnal, making them distinct among social wasps in North America, and are notably attracted to exterior lighting. They are predatory insects, primarily foraging on a wide range of live insects, including grasshoppers, flies, and large caterpillars, which they chew and feed to their larvae. Adults also supplement their diet with tree sap and ripe fruit, making neat incisions in bark, particularly from lilac, birch, and ash, to access cambium and phloem. While generally less aggressive than yellowjackets when foraging, they become fiercely defensive if their nest is disturbed, delivering a painful sting due to their larger venom sac and smooth stingers, allowing for repeated stinging. Public health impacts arise from potential allergic reactions to their potent venom.