The bald-faced hornet is sometimes called the white-faced hornet, but is actually a yellow jacket. It’s easy to spot since it’s our only black and white yellow jacket. Its nest is a gray “paper” envelope with several layers of combs inside. A mature nest is bigger than a basketball, but pear-shaped, with the larger end at the top and an entrance hole near the bottom.
A single, over wintering queen begins building the nest in the spring. She lays eggs and tends the first batch of larvae that develop into workers. These workers tend new larvae and expand the nest throughout the summer. A mature colony can have several hundred workers by the end of the summer. In fall, workers die and next year’s queens find over wintering sites.
Bald-faced hornets are beneficial, capturing insects (often including other yellow jackets) to feed to their larvae. Though larger than other yellow jackets, bald-faced hornets are generally more docile. But they can become aggressive and will sting when their nest is disturbed or threatened.
A bald-faced nest is usually constructed high in a tree. In these cases the nest is best left alone. In fact, bald-faced hornet nests are often first noticed in fall when leaves drop, exposing the nest. By this time the hornets are dead or dying, and the nest will not be reused.
Occasionally you will find a bald-faced nest built on the side of a building, in low shrubbery, or even in an attic or shed. Nests in these sited will probably need to be eliminated.