Green Stink Bug (Acrosternum hilare)
Identification: Stink bugs are true bugs (Order: Hemiptera). All insects in Hemiptera share a few characteristics, including piercing and sucking mouthparts, and wings which are membranous and clear at the tips, but hardened at the base. Stink bugs are distinguished from other members of Hemiptera by their broad, shield-shaped bodies, 5-segmented antennae, and large "scutellums". (The scutellum is a triangular-shaped part of the thorax. Although it is present on all insects, it extends halfway down the backs of stink bugs and is very noticeable.)
Several species of stink bugs are green or include green in their color pattern. The three black bands on the outermost antennae segments help identify this specimen as A. hilare. (There are also differences in the shape of the stink gland pore located on the underside of the bug. These are explanined on BugGuide.)
Food: Like most stink bugs, A. hilare is herbivorous. It uses its piercing mouth parts to feed on plant juices. (A few species of stink bugs are predatory.) Stink bugs can cause serious damage to food crops when they feed on developing fruits. Feeding damage is caused when they insert their piercing/sucking mouthparts into the plant, inject digestive enzymes, extract plant juices and allow entry of pathogenic microorganisms. The fruits then wither or become deformed. (This disfigurement or malformation is sometimes called catfacing.)
The Stink: Stink bugs get their name because they are able to secrete a bad-smelling, bad-tasting fluid from pores on the sides of their bodies (many other members of the Hemiptera can do this as well). This is a defensive mechanism used to keep predators like birds, mice and lizards from eating the bug. It usually takes severe harassment to provoke stinkbugs into releasing their chemical defenses because producing these chemicals requires a significant energy investment from the bug. (I have accidentally crushed stink bugs when they attempted to crawl under my shirt collar and can attest to the fact that the smell released is strong, unpleasant and isn't easily washed off.)
The exact chemicals released by stink bugs vary by species, but they are all aldehydes. Aldehydes do not inherently smell bad, but stink bugs concentrate these chemicals so much that they become wholly unpleasant, even irritating. The smell can even kill the stinkbug itself. If the bugs are collected in stoppered vials, or kept in cages without adequate ventilation, the chemicals can get into their respiratory system and asphyxiate them.
While these aldehydes are distasteful and even toxic to birds and other predators, according to one particularly dedicated scientist, Dr. Bryan Krall of Parkland College, stinkbugs taste to humans like red-hots or cinnamon gum. (No matter how much I'm goaded by Tom W., I refuse to eat a stink bug.)
Range and Habitat: A. hilare can be found just about anywhere outdoors throughout North America. (BugGuide says: "Fields, meadows, yards & gardens on herbaceous plants and low shrubs.")
(Photo taken last July)Life Cycle: Like all Hemiptera, stink bugs go through a simple metamorphosis with egg, nymph, and adult stages. During warm months, female stink bugs lay barrel-shaped eggs which are stuck in clusters to leaves and stems. Emerging nymphs are gregarious and remain on or near the egg mass. As they develop, they begin to feed and disperse. The wingless nymphs molt several times before becoming full-sized, winged adults. Large nymphs or adults are usually the overwintering stage.
