BALDFACED HORNET
Common Name: Baldfaced hornet
Scientific Name: Dolichovespula maculata
Introduction. This atypically large black-and-white yellowjacket gets its common name of baldfaced from its largely black color but mostly white face, and that of hornet because of its large size and aerial nest. Baldfaced hornets are found throughout the United States.
Recognition. Adult workers are about 5/8 to 7/8 inch long. The queens measure 3/4 to 1 1/8 inch long. They are colored black with a white pattern on most of the face, white stripes on the thorax and white bands on the last 3 abdominal segments. Baldfaced hornets build a grayish paper nest shaped like an inverted pear and attached to branches or a recessed sheltered surface on a building.
Similar Wasps. (1) Yellowjackets (Vespula species) have yellow and black alternating markings on all abdominal segments. Yellowjacket workers are usually less than 5/8 inch long. (2) The European hornet (Vespa crabo) measures 1 to 1 1/4 inch long and has yellow, rust and brown body markings. The brown paper nest is concealed.
Biology. Baldfaced hornets are social insects which live in aerial nests. The adults are represented by workers (sterile females), queens, and males (which develop from unfertilized eggs and usually appear in the late summer). Only inseminated females overwinter and do so in sheltered places. In the spring, the queens use chewed-up cellulose material to build a paper carton nest of several dozen cells covered by a golf ball-size paper envelope. One egg is laid in each cell as it is constructed. The queen feeds the developing larvae chewed-up insects, spiders and nectar. After about 30 days, the first 5 to 7 workers emerge and shortly thereafter take over all the work except for egg laying. By late September the nests consist of 3 to 5 disk-like paper combs attached one below another, and encased in a multi-layered envelope. Nest size varies from less than 2000 cells to 3500 cells and contains 100 to 400 (maximum 636) workers at its peak. Later in the season, larger reproductive cells are built in which queens and males are 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.
Habits. The overwintering queen selects the nest site. This can vary from shrubs or vines at ground level to 66 ft or higher in trees. Nests may also be built on overhangs, utility poles, houses, sheds, or other structures. Nearly all nests are constructed in sheltered locations. At maturity, the nests can be quite impressive with sizes of up to 14 inches in diameter and over 24 inches in length.
Often nests located in vegetation are not discovered until the leaves fall in the autumn. Nests are not reused the next season.
Cultural Control & Precautionary Measures. If a bladfaced hornet nest is high up in a tree, control measures may not be necessary. However, if the nest is low to ground and near a heavily trafficked area or has been discovered by children, then Rottler should be called to treat the nest with a residual insecticide. Nest removal is optional. Children should be prevented from throwing rocks at hornet nests because these insects defend their nests aggressively and the stings are very painful. A disturbed or recently treated nest should be roped off and avoided until activity has ceased.
Professional Control. Baldfaced hornets are beneficial insects by helping to control many pest insect species and spiders. However, if the nest is located close to the ground and near an occupied structure or recreational area, then control is warranted.
A Rottler pest management professional wearing a protective garment will apply an appropriately labeled aerosol or dust insecticide through the entrance hole at the bottom of the nest. For high nests, a dust stick or “bee pole” allows application of the insecticide from the ground or a sizeable distance away and gives added safety for the applicator. The nest may be removed, placed in a garbage bag, and discarded or preserved for display at a later time.
Baldfaced hornet nest on tree branch.
Locations
Serving the St. Louis Metropolitan area since 1956, including
Arnold, Ballwin, Chesterfield, Crestwood, Creve Coeur, Des Peres,
Fenton, Florissant, Kirkwood, Maryland Heights, Overland, St.
Charles, Webster Groves, Wentzville and surrounding areas.
In Illinois: Belleville, Collinsville, Edwardsville, Columbia,
Madison, Waterloo, O’Fallon, Granite City, Alton, St. Clair, Monroe
and surrounding areas.
Columbia & Jefferson City, MO and surrounding areas.
