Bald-Faced hornets build grayish paper nests, that resemble large misshapen soccer balls, in shrubs, hanging from tree branches, and attached to buildings, and can become quite large by late summer, sometimes approaching the size of a basketball! The hornets are shiny black with a white head and tail and are quite large, being over an inch in length. If the nest is 15' or more high, they will probably not be a concern and can be left alone to do their thing. The nests can be concealed, and not discovered until someone starts trimming hedges, shrubs, etc. Be extremely careful doing that type of work anytime from mid-July until late October. They, along with wasps, and yellowjackets are very beneficial because they feed on other insects, especially caterpillars which they use to feed their larvae. If disturbed, they can be very dangerous, because they are extremely aggresive, attack in large numbers, and each one can sting multple times. A nest only lasts for one season. In August-September, an existing nest raises new queens which mate in the nest and then leave and go dormant for the winter. A good hard freeze in late Fall-early Winter kills the existing nest and in the Spring (usually around mid-May) the new queens emerge from their winter dormancy and start building new nests. If they occur in the same spot again it is only because it is a good spot for them, not because there is any connection to an old nest.