Bald-faced hornet is constructed too close to human habitation. They vigorously defend the nest, with workers stinging repeatedly, as is common among social bees and wasps. However, the baldfaced hornet has a unique defense in that it can squirt or spray venom from the stinger into the eyes of vertebrate nest intruders. The venom causes immediate watering of the eyes and temporary blindness. The life cycle of a colony can be divided into the founding stage, the ergonomic stage and the reproductive stage. Colonies show annual cycling. New nests are generally founded during spring and early summer by a single queen, though
Bald-faced hornet colonies have been observed in central Pennsylvania as late as mid-October. The colony is founded by a single overwintered, inseminated queen. She rears the first generation of workers on her own until they are functional. Colonies pass through the foundation over an average period of 23–24 days. After the queen lays her eggs, it takes 6 days for them to hatch. They grow as larvae for eight days. It takes them an additional 9–10 days to mature into adult workers. During the ergonomic stage, the colony's activities are concerned with cell building and worker production. The queen devotes herself entirely