Yellowjackets receive their common name from their typical black and yellow color pattern. They are worldwide in distribution with about 16 species occurring in the United States.
Adult Yellowjacket workers are about 3/8” to 5/8” long, with black and yellow striped abdomens. The Yellowjacket queens are typically 25% larger than the workers. When flying, Yellowjackets’ legs are not easily visible because they keep their legs tight against their body.
Yellowjackets are social insects and live in nests or colonies. Typically, only Yellowjacket queens overwinter and do so in sheltered places such as under logs or stumps, but often in attics as well. In the spring she will burrow into the ground to begin a nest by using chewed-up cellulose material to build a paper carton nest of up to 50 cells, often covered by a paper envelope. One egg is laid in each cell and the queen feeds the developing larvae protein from insect prey and nectar. After about 30 days, the first 5-7 workers emerge and take over all the work except the egg laying. The Yellowjacket nest will eventually consist of a number of paper combs attached one below another and be covered with a many-layered paper envelope. Nest sizes average between 2,000 and 6,000 cells, and usually contain from 1,000 to 4,000 workers. Later in the season, reproductive females and males are hatched to mate so the new queens can overwinter.
Yellowjackets most often build their nests in the ground, selecting an area bare of vegetation or else clear an area around the entrance and there are nest entrance guards to protect the colony. Yellowjackets are typically slow to sting unless the nest entrance is approached and they are extremely aggressive. Each Yellowjacket can sting multiple times, inflicting much pain.
Yellowjackets are considered beneficial insects because their food consists mostly of other pest insects, often spiders or other pest species. However, if the Yellowjacket nest is located close to an occupied building, recreational areas or within structures, then control is needed. Treatment of Yellowjacket nests consists of injecting into the nest with an appropriate pesticide and due to the aggressive nature of Yellowjackets this should only be done by a trained and licensed pest control operator.