Several species have economic importance, because they are among the pollinators of commercial crops, and because some feed on such destructive caterpillars as the corn-ear worm and army worm. A species that is native to Africa is known to prey on the eggs of the rhinoceros beetle, an insect that causes immense damage in coconut-growing regions. Many parasitic varieties, which lay their eggs in the body or egg of the host, are useful in the control of some injurious pests such as aphids, codling moths, and bollworms. Nesting Habits Social wasps build papery nests of masticated fibers. The nests of yellow jackets and hornets are composed of several layers of cells enclosed in a globular outer covering.
Paper wasps build open, flat nests of a single comb.
The nest is begun by the queen wasp, which alone survives the winter. The first eggs develop into workers, which continue the nest building and largely take over the care of the young. Several thousand yellow jackets may exist in one community. The nesting habits of the solitary wasps are extremely diverse. The potter wasps build vaselike cells of clay attached to the twig of a tree.