In spring, usually May, the queen emerges from hibernation and begins to build her papery nest. The queen lays eggs which hatch into smaller (18-25mm ) sterile female workers. When 5-10 workers have emerged, the queen will leave the nest building and food collecting to them, and will concentrate on laying more eggs. On calm, warm nights worker hornets may be seen foraging for food. Later in the summer males (measuring 21-28mm) and fertile females hatch. On a warm day, the males and fertile females swarm from the nest and mate. As the weather becomes cooler in October/November, the newly mated female hibernates, and, if she survives, she will become the new queen the following spring. The males, the old queen and the workers all die.