Adult shield bugs are attractive insects, easily recognized by their flat oval or five-sided shield shape. They are often called stink bugs because when threatened, some species produce a pungent liquid from special glands near their hind legs, poke at one and then sniff your hand.
Most shield bugs feed on plant sap and some are pests of economically important crops such as coffee and cotton.
Few gardeners would consider them to be pests, although the noxious liquid they produce can taint the taste of some fruit. Most shield bugs need symbiotic bacteria for the digestion of the sap. They acquire this aid to digestion at an early age, their mother smears her eggs with the bacteria so that the young nymphs ingest them as they feed on the egg case.
Unlike many insects, shield bugs often show parental care, guarding their young against predators. The female will actually sit on the eggs until they hatch. This reduces the chances of an attack from parasitic wasps.
Bean plants damaged by stink bug feeding and egg-laying emit an odor that is attractive to parasitism wasps, which then attack the bugs.