This article was published originally on 8/27/2008
Balfaced hornets are large social wasps that construct oblong to round nests in trees during the course of the summer. The nests start small with a single queen in early summer. As the queen reproduces and as her daughter-workers enlarge the nest and the colony, the population grows to a few hundred individuals and the nest grows to the size of a basketball. Nests are usually attached to a tree branch but may be attached to shrubs, utility poles or house siding.
Baldfaced hornets are ecologically beneficial and often co-exist with people for the entire summer without incident. Hornets are not overly aggressive and high nests in out-of-the-way locations can be ignored until frost when the residents all start to freeze to death or die of old age. All the wasps are gone from the nest after a few hard freezes.
A nest in a high traffic area or low to the ground, or a nest in the vicinity of curious thrill seekers who can't stay away should be eliminated to prevent the slight chance of being stung. This can be done at night by spraying a wasp and hornet aerosol insecticide (the kind that shoots insecticide 10+ feet) into the nest opening at night. There is more information on our web site.
If you are interested in saving a hornets' nest as a decoration or conversation piece see the on-line article, "Preserving and Displaying a Hornet's Nest."
Baldfaced hornet nest with hornets. Photo by Jane Cavanaugh.
IC-499(16) -- August 27, 2008