The Bald faced hornet (Dolichovespula maculata) are black and white,
5/8 to 3/4 of an inch long and are actually a yellowjacket.
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.
Baldfaced hornets are beneficial, capturing insects (often including other yellowjackets) to feed to their larvae. Though larger than other yellowjackets, Baldfaced hornets are generally more docile. But they can become aggressive and will sting when their nest is disturbed or threatened.
A Baldfaced nest is usually constructed high in a tree. In these cases the nest is best left alone. In fact, Baldfaced 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 Baldfaced nest built on the side of a building, in low shrubbery, or even in an attic or shed. Nests in these sites will probably need to be eliminated.
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