The European Hornet is a social insect, living in nests or colonies. The majority of adults are workers including sterile females, males, and queens, which emerge from unfertilized eggs in the late summer. The inseminated females overwinter in a protected area. In the spring, the female hornets use chewed cellulose from decayed would to create a paper-carton nest with dozens of sells covered in a brown envelope. Each cell receive a single egg and the queen hornet feed developing larvae with arthropod proteins and nectar. The first five to seven workers finish development after thirty and immediately begin working. The queen is attended by several worker hornets.
The average European hornet nest will contain six to nine paper combs with ventral openings attached one below the other. If the nest is build in an unprotected area, it will be covered in paper envelope; however, if the environment is protected, there will be little to no paper envelope. An average, mature hornet nest will consist of 1,500 to 3,000 cells and six to nine combs. The record high is 33 combs with 5,566 cells. A large colony, at its peak, will hold around 1,000 workers. A typical colony, however, has 200 to 400 workers. Larger reproductive cells are built later in the seasons. These cells will yield queens and males; the males are reared in older worker cells. At this point, the colony is in a declining phase. The new queens and males leave the nest to find mates. Inseminated queens are the only hornets that hibernate to survive the winter. The founding queen, the workers, and the rest of the males all die during the winter months.