Paper wasps are colored yellow, black, brown, and red, depending on the species, with 3/4- to 1-inch long slender bodies. They build paper nests of a single comb (Figure 1) attached to trees, shrubs, and a variety of structures, such as building eaves. Their paper nest is derived from weathered wood or plant sources chewed and mixed with the wasps’ saliva. The colony begins in the spring when a mated female leaves her hibernation site to build her nest. Usually a single female initiates the nest, but in some species other females may join the original female and help build the nest and care for the young. The emerging young become the workers and gather paper and food, and of course, defend the nest. One of the original females does less colony work and becomes the sole egg layer or queen. The paper wasp queen is not obviously larger than the workers.
The colony grows rapidly through the summer, and the maximum colony size is usually reached in late summer or early fall. The typical mature paper wasp colony usually contains 20 to 75 adults on a nest 3 to 10 inches in diameter. These summer colonies are probably the most defensive and certainly the most threatening to humans. In the late summer and early fall, males and future reproductive females are produced. As the workers begin to die in the fall, the reproductives leave the nest to mate. Mating aggregations occur around elevated structures such as tree tops, towers, and high-rise buildings and near hibernation sites. Although such large numbers of wasps would appear to be a dangerous stinging hazard, most of these wasps are males, who lack a sting, and nonaggressive females primarily interested in mating and hibernation. After the mating season, the males soon die, while the mated females seek hibernation sites to survive the winter. The following spring, the annual cycle is repeated as females emerge from hibernation and initiate a new nest, sometimes in close proximity to their parental nest. However, they rarely re-use a previous season’s nest.