Workers are 3/4 to 1 3/8 inches long. Their color is muted shades of brown with light orange bands across each segment of the abdomen. These might be confused with cicada killer wasps; however, cicada killers have brighter yellow spots on the first 3 abdominal segments that do not form complete bands across the abdomen. Nests are similar to baldfaced hornet nests with combs wrapped in a paper envelope to create a large, round structure, but European hornet nests are typically brown or tan in color rather than gray.

European hornets, the only true hornet found in the United States, were actually introduced from Europe in the mid-1800s. They are not common in urban areas and prefer forested areas with nesting sites such as hollow trees and old wooden structures, but they will also nest in attics and old beehives. Queens emerge in spring to initiate colonies. They create the first comb, lay eggs, and care for the first brood of 5 to 7 workers. Once the adult workers emerge, they take over colony duties, while the queen settles down to lay eggs. The colony consists of a queen and 200 to 400 workers at its peak. Males and new queens are produced in late summer in preparation for mating flights, and inseminated queens overwinter in protected locations. European hornets are predators of many larger insects, such as grasshoppers, yellowjackets, and flies.

European hornets are not a common hazard to humans because they prefer forested areas and can be difficult to find. When encountered, these wasps are relatively nonaggressive around the nest. However, workers can girdle (strip the bark off) young trees and ornamental shrubs to feed on the sugary sap, a habit that can kill affected plants. Workers are primarily active during the day, but they are also attracted to lights at night and have been known to bang against lighted windows at night.