The bald-faced hornet (Dolichovespula maculata) is technically a species of aerial yellowjacket, despite its common name and large size. The population count within the nest is not static; it changes dramatically throughout the season. The final number of hornets depends entirely on the length of the growing season and the success of the founding queen.
Identifying the Bald-Faced Hornet and Its Nest
The bald-faced hornet is readily identified by its striking black and ivory coloration, which sets it apart from the black and yellow markings of other yellowjackets. The insect has a predominantly black body with distinct white or ivory patches, most notably on its face, which gives the species its common name. Workers typically measure between 12 and 15 millimeters in length, making them noticeably larger than many other social wasps in North America.
Their nests possess a unique physical signature, constructed from a papery material made by chewing wood fibers and mixing them with saliva. This construction creates a gray, multi-layered outer shell that protects the internal horizontal combs. The nest shape is often described as resembling a football or an inverted teardrop. These structures are built in aerial locations, commonly found attached to tree branches, utility poles, or under the eaves and overhangs of buildings.
Population Dynamics and Peak Colony Size
For a mature nest observed during late summer, the typical population ranges from approximately 100 to 400 worker individuals. This count represents the peak density achieved before the colony begins to decline in the autumn months. The final number is influenced by factors such as food supply and local climate, which dictates the length of the warm foraging season.
In exceptional circumstances, particularly in areas with long, warm summers and abundant resources, a bald-faced hornet colony can reach an absolute maximum of 500 to 700 workers. These higher counts are achieved because the queen focuses solely on laying eggs. The workers’ continuous efforts to forage for protein, primarily other insects, and to expand the nest directly fuel the population boom.
This sustained rate of growth allows the colony size to double or triple within a few weeks during the height of the summer. The population count is highest in late August and early September, which is when the nest is at its maximum physical size and activity level. This peak signifies the colony’s transition to producing reproductive individuals rather than more workers.
The Annual Lifecycle of the Colony
The annual cycle begins in the spring when a single fertilized queen emerges from her overwintering location. She is the founder of the colony and undertakes the initial construction of a small, golf-ball-sized nest. The queen lays her first batch of eggs in the newly formed cells and personally forages for food to feed the developing larvae.
This first brood of eggs matures into sterile female workers, which usually takes about a month from the time the eggs are laid. Once these first workers take flight, the queen remains within the nest and dedicates her energy exclusively to egg production. The newly emerged workers take over all responsibilities, including expanding the nest, gathering food, and defending the structure.
As the summer progresses, the queen eventually begins to lay eggs that will develop into the next generation of reproductives. These eggs are fertilized to produce new queens, and unfertilized eggs produce males, sometimes referred to as drones.
The new queens and males leave the nest in the fall to mate. The newly fertilized queens then seek out a protected place to hibernate. The original queen and all her workers perish with the onset of the first hard frost, returning the nest’s population to zero.