A large, carnivorous bug, about an inch and a half long. Adult resembles a battle robot from a science fiction movie, and comes in battleship gray, or darker, with a large, gear-like protuberance on the back. Head is small, with a prominent black eye, and a huge mouthpart. It kills insect prey, and injects enzymes through its mouthpart. The enzymes dissolve the tissues, which it then sucks out. The one below right is lying in wait for prey; the other photos show one with a small wasp it has killed. Nymphs are rather spider-like, black with a brilliant red abdomen that curves upward. Nymphs are also predators of smaller insects. They are wingless, but the adults can fly.

 The female lays a tightly packed cluster of large eggs (bottom) on the side of a tree, each egg about a quarter inch long. The eggs are sticky, shiny black, and have a dull brown top. The eggs overwinter and the nymphs hatch out in the spring. On hatching, they must flee before being eaten by their siblings.

Despite their fearsome appearances, the nymphs and adults are shy. However, if disturbed the adults can inflict a painful bite, and also shoot stink from their rears, like other stink bugs.

A fairly common native in the Park. Generally considered a beneficial insect as many of the insects it eats are pests. Eggs, nymphs and adults are all distinctive looking, and unlikely to be confused with any other animal.