Bald-faced Hornets are common tree-nesting wasps. They grow to 3/4 inch long.
These hornets are easy to recognize because of their color pattern. The head, thorax, abdomen, and antennae are black and white. Wings are smoky.
Bald-faced Hornet nests are usually found in meadows, forest edges, gardens, and parks.
Nests are made by chewing up strips of wood and mixing it with sticky saliva. One nest may hold up to 700 hornets.
A nest is started by one female, which will become its queen. In the spring, she begins the nest by making a few cells (little round rooms) out of paper in a tree or shrub, anywhere from 2 to 40 feet from the ground. She then lays an egg in each cell. When young wasp larvae hatch, the queen feeds them. Larva are fed chewed up insects.
When larvae are big enough, they pupate (resting stage). They soon emerge as adult female workers.
Workers take over all nest duties, and the queen’s only job now is to lay more eggs. Workers build new layers of cells onto the nest, collect food, feed larvae, and protect the nest.
Throughout the summer, the nest gets bigger, until it’s about the size of a basketball. All of the new hornets are female workers.
At the end of summer, or in early fall, the queen lays eggs which will become females and males. These insects mate, and then all of the nest’s hornets die (including the old queen), except the females who have mated.
Mated females overwinter and start their own nests next spring. They often burrow into an old tree stump to survive the cold.
Old nests are abandoned. You can see old nests in winter, hanging in trees when leaves have fallen.
Nests are interwoven with branches and twigs. This makes sure they are strong and don’t get destroyed by weather. The entrance hole is near the bottom of the nest.
Adult Bald-faced Hornets eat flower nectar, fruit juice, sap, and insects. Workers kill many insects and chew them up to feed larvae.
Predators of adult hornets include birds, spiders, frogs, mantids, and other insect predators.
Nests are preyed upon by Raccoons. Fox and Striped Skunk will also raid them if they’re close to the ground. These mammals usually rip them open in the fall, when nests aren’t as active. They eat adults, pupae, and larvae.
Bald-faced Hornets are very protective of their nest. If threatened, hornets will sting repeatedly. Great care should be taken before trying to remove a nest. Hornets will sometimes build nests around people, such as under house eaves and gutters, or on power or telephone poles.