Yellowjackets are more closely related to bald-faced hornets than hornets. The body of the bald-faced hornet is black, with white markings on its face. The workers of bald-faced hornets are bigger than those of other yellow jackets, measuring 15 to 20 mm or more. Within a few months, a bald-faced hornet nest can grow to be the size of a basketball. The nest may house up to 700 employees. Late in the summer, males emerge. Some of the freshly produced females are fertilized by the males.
While bald-faced hornets can be useful by preying on other pests, their nests should not be allowed to develop near a dwelling. When workers are upset, they become defensive and aggressive.
The most active time for bald-faced hornets is throughout the day. Aerial nests made of paper are generally built in trees or beneath overhangs. In the spring, queens emerge from their overwintering, protected hiding areas to begin building new nests. Tree hollows and thick bushes and trees are common places for bald-faced hornet nests. A queen seeking for a warm place to spend the winter may enter through cracks in the roof or around the eaves. Infestations are more likely to occur in yards with a lot of protected locations.
These pests are fiercely protective of their nests, attacking and stinging persons and animals they perceive to be a danger. A bald-faced hornet can strike a target repeatedly without injuring itself because of its smooth stinger. When they "zone in," they frequently attack in huge groups. This implies that the insects may inject a huge amount of venom, perhaps causing painful swelling or a considerably more dangerous allergic reaction.
The first line of protection against hornets encounters is to prevent hornets from nesting around your property. Solitary hornets in the house can be a nuisance; regular observations of hornets in the house may imply indoor nest construction, and the situation requires additional attention. The greatest line of defense is to find and seal off their point of entrance. Unsealed vents, ripped screens, gaps in windows and door frames, and open dampers are all things to look for in your home. Observe a hornet’s flight route, particularly early in the morning, since it may disclose the entry/exit location.