Adult shield bugs are attractive insects, easily characterised by their flattish oval or five-sided shield shap (the pentatomids). They are often called stink bugs because when threatened, some species produce a pungent liquid from special glands near their hind legs (poke 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 from predators. The Parent Bug (Elasmucha grisea) is so named because the female will actually sit on the eggs until they hatch. This reduces levels of attack from parasitic wasps.
In Mexico Stink Bugs are eaten both live and cooked (for instance in a pate or salsa) since their pungent odour gives a dish an aromatic flavour.
Some stink bug species have switched from feeding on plant juices to feeding on "insect juices" including caterpillars.
Bean plants damaged by stink bug feeding and egg laying emit an odour attractive to parasitoid wasps, which then attack the bugs.