Brown marmorated stink bug (Halyomorpha halys) grooms one of its antennae by stroking it with its front legs. These insects are native to Asia and were accidentally introduced to the United States in the late 1990s. It is an agricultural pest that can cause widespread damage to fruit and vegetable crops. Stink bugs get their name from the pungent odor they emit through holes in their abdomen when alarmed or threatened. They measure less than 20 mm across.