This atypically large black-and-white wasp gets its common name of baldfaced hornet from its mostly white face, with marginal black markings, as well as its large size. It is also known for its typically large aerial nest. Baldfaced hornets are found throughout the Kansas City area as well as the rest of the United States.
Baldfaced hornets are beneficial insects, controlling many pest insect species. However, if the nest is located close to the ground or near an occupied structure or recreational area, control may be warranted.
Adult workers about 5/8-3/4 inch long; queens about ¾+ inch long. Their overall color is black with a white pattern on most of face, along with 2 angled stripes behind the head and on the last 3 segments of the body.
- Yellowjackets (Vespula spp.) with yellow markings including on 1st 3 abdominal segments, usually less than 5/8” (15 mm).
- European hornet (Vespa Crabro) with pale markings on 1st 3 abdominal segments, nest envelope brown.
Baldfaced hornets are social insects which live in aerial nests. The adults are represented by workers which are sterile females, queens, and males which come from unfertilized eggs and usually appear in the late summer. Inseminated females overwinter in sheltered places. In the spring, they use chewed-up cellulose material to build a paper carton nest of several dozen cells covered by a paper envelope. One egg is laid in each cell as it is constructed. The queen feeds the developing larvae arthropod protein material and nectar. After about 30 days, the first 5-7 workers emerge and shortly thereafter take over all the work except for egg laying. The next will eventually consist of 3-5 rounded paper combs covered with a many-layered envelope. Nest size varies up to 3,500 cells in 5 combs but usually consists of less than 2, 000 cells in 3-4 combs and contains 100-400 workers at its peak. Later in the season, larger reproductive cells are built in which queens and males will be reared; males are often reared in old worker cells. The colony is then entering the declining phase. The newly emerged queens and males leave the nest and mate. Only inseminated queens hibernate and survive the winter. The founding queen, the workers, and the males all die.
The overwintering queen selects the nest site. This can vary from shrubs or vines at ground level to over 50 feet or higher in trees. Nests may also be built on overhangs, utility poles, houses, sheds, or other structures. Nearly all nests are constructed in exposed locations. At maturity, the nests can be quite impressive with sizes of up to 14inches in diameter and over 24 inches in length. Nests located in vegetation often are not discovered until the leaves fall in the autumn. Nests are not reused the next season.
During the day locate the nest. Control should be done at night when most of the bald-faced hornets are in the nest. Only background lighting should be used and a bee veil should be worn. Apply an appropriately labelled aerosol through the entrance hole at the bottom of the nest. For high nests a “bee pole” which allows application of the aerosol from the ground or a sizeable distance away gives added safety for the applicator. The nest should be removed, placed in a plastic garbage bag, and discarded so that no emerging pupae can cause problems.
This work is best done by the highly-trained technicians at Augustine Services, Inc. Call them at 913-362-4399 in Kansas, or 816-421-6882 in Missouri.