The green stink bug, Acrosternum hilare, and its cousins are plant pests. The wingless youngsters (called nymphs) get more colorful with each shedding of their skin. Toward the last instar, the nymphs look like this photo, then they shed and become green with orange edges. Stink bugs are shield-shaped and look like they're wearing armor. They can give off an unpleasant odor when disturbed thus earning their name.