Bald-faced hornets are a species of social wasp, recognized by their distinctive black and white markings, particularly on their face. They are not true hornets, but rather a type of yellowjacket. These insects build large, gray, papery nests, often football-shaped, in elevated locations such as trees, shrubs, or on buildings. Their nests are constructed from chewed wood fibers mixed with saliva, creating a pulp-like material.
The Annual Life Cycle
The life cycle of a bald-faced hornet colony begins in spring when a single fertilized queen emerges from hibernation. She selects a suitable nesting site and constructs a small starter nest, laying her first batch of eggs. These eggs hatch into larvae, which the queen feeds with insects she forages.
The first offspring to emerge are sterile female workers, which then take over the duties of expanding the nest, foraging for food, and caring for subsequent generations of larvae. This allows the queen to focus solely on laying more eggs, significantly increasing the colony’s size. By mid-to-late summer, a mature colony can contain hundreds of workers. Towards the end of the season, the queen produces a final brood that includes new queens and males.
The Colony’s Demise: When Death Occurs
Bald-faced hornet colonies are annual, meaning they do not survive through the winter. As cooler weather arrives in late fall, the active colony begins to decline. Environmental factors, such as decreasing temperatures and a reduction in available food sources, contribute to the demise of the workers and males.
The workers, old queen, and males perish with the onset of freezing temperatures. Unlike the newly produced queens, the old queen does not survive the cold.
The Fate of the Nest and New Queens
After the active colony dies, the large, papery nest is abandoned. These nests will deteriorate over the winter months due to weather exposure. The structure often remains visible in trees after leaves fall, serving as a reminder of the past season’s activity.
Only the newly fertilized queens, produced late in the season, survive the winter. These new queens leave the nest and seek sheltered locations, such as under tree bark, inside hollow trees, in leaf litter, or within attics. They enter a state of hibernation. With the return of warmer temperatures in the spring, these overwintered queens emerge to begin new colonies.