Found across a majority of the United States and Canada, baldfaced hornets are not a ‘true’ hornet, they are an aerial yellowjacket. The only ‘true’ hornet in North America is the European hornet, which is an accidentally introduced species. The baldfaced hornet’s name comes from the white to ivory colored markings on its face. Ivory or white markings are also found on the thorax, legs and abdomen. The queen and her offspring range in size from roughly ½ to just over ¾ of an inch in length. As with most yellowjackets, baldfaced hornets are highly aggressive and will attack anything within their space, especially near their nest location.
Springtime is the beginning of baldfaced hornet activity for the year. Fertilized queens that have overwintered in areas sheltered from the cold of winter begin to emerge from hiding and seek out a location for her new nest. Cellulose is collected from weathered or rotting wood. The queen adds her saliva to form a paste and begins constructing the papery material of her nest. A few brood cells are created within the nest and eggs are deposited inside. The queen feeds and cares for her first brood, which when grown assume the responsibilities of nest building and expansion, collection of food, care of larvae and the protection of the nest. By the end of summer, most colonies have expanded to between 100 to 400 workers. Nests are located a minimum of three feet off the ground and are primarily located in trees and bushes, although the are also found suspended from sheltered areas of manmade structures at times. Air vents at the top of the teardrop shaped nest allow heat to escape without allowing rain to enter the nest. Some nests can be rather large measuring up to 24 inches in height and 18 inches in diameter. Primarily gray in color, most baldfaced hornets’ nests have off-white to light brown banding throughout the nest material.
Food sources will change as the year progresses. Early in the spring and summer a majority of the baldfaced hornet’s diet consists of proteins obtained from hunting flies, insects and even other yellowjackets. It is this feeding habit that can classify baldfaced hornets as a beneficial insect; however, their aggressiveness and ability to sting are often considered more of a downfall than the benefit of insect control. Later in the season, as the queen begins to produce less and less larvae, workers often switch to nectar or other carbohydrate based diet. Most of the colony, aside from newly fertilized potential queens will begin to die of around the time of the first hard frost when the queens seek out their winter shelters.
Extermination and removal of active baldfaced hornets’ nests is best left to a well equipped professional. Spraying the exterior of the nest will only result in aggravating the yellowjackets inside and will likely result in multiple stings. Appropriately labeled pesticides must be applied directly into the entry of the nest in order to be affective and when not done properly can also result in being stung. Inactive nests located during the winter can often be simply knocked off of the branch from which they are suspended.