Like other social wasps, hornets build communal nests by chewing wood to make a papery pulp. Each nest has one queen, who lays eggs and is attended by workers who, while genetically female, cannot lay fertile eggs. Most species make exposed nests in trees and shrubs, but some (like Vespa orientalis) build their nests underground or in other cavities. In the tropics, these nest may last year-round, but in temperate areas, the nest dies over the winter, with lone queens hibernating in leaf litter or other insulative material until the spring.

Hornets are often considered pests, as they aggressively guard their nesting sites when threatened. This is particularly true for hornets nesting close to human habitation, as their stings are more dangerous than those of bees.