Friday, April 18, 2008

Green Stink Bug


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.


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12 comments:

evlahos said...

you have wonderful nature and macro pics here. well done

Lisa at Greenbow said...

While I would rather be seeing butterflies this time of year I have seen a couple of stink bugs already.

Your picture of the eggs and larve is great! I think I have seen those eggs here before but didn't know what they were.

Did you feel the earthquake today?

Dave said...

We find stink bugs a lot on black raspberries. I've even eaten them by mistake - BLECHH. But even a berry that has had a stink bug on it can taste bad.

Old Wom Tigley said...

LOL.. Thanks for the mention.. but please. go on just for me.. try at least one... ha!

We call these Sheld bug.. now I've read this I did to taste them but who do I know nearby that will do this... PETER.. ha!

Small City Scenes said...

Ah Stinkbugs and summer memories. There are always stinkbugs on Raspberries and when I was a kid picking berries and we would find a stinkbug what fun would be had by chasing everyone. Of course the row bosses frowned at this behavior but it always got a laugh. MB

kirispupis said...

It's funny how sometimes we think of things at the same time. I posted a blog about stink bugs recently, but you have found much more information than I knew. Nice shot of the baby stink bugs!

Marvin said...

Wouldn't ya know it: Someone schedules an earthquake and I sleep through it. According to the news reports that I looked at, we should have been right on the edge of feeling the quake, but it occurred around 4:30 AM and I'd gone to bed a little after four o'clock.

Ted C. MacRae said...

Hi Marvin -- thought you might be interested to know that the order Hemiptera now also includes insects formerly placed in the order Homoptera (aphids, scales, hoppers, and cicadas). These insects were distinguished from Hemiptera based on their wholly membraneous wings held roof-like over the body. However, recent studies have made it clear that hoppers/cicadas are more closely related to true bugs than they are to aphids/scales, thus the necessary change in classification. Piercing/sucking mouthparts is a common feature uniting all these insects into a single order.

Marvin said...

Thanks for keeping me up to date, Ted. I will readily admit that as a layman who's learned what little I know about entomology in a very piecemeal fashion, taxonomy intimidates me. The only thing more intimidating is trying to key out an insect. There's just too much terminology I don't know.

smilnsigh said...

You had an earthquake?

We have them up here, now and then too. I felt the last one, which was a while ago. Sitting at computer, feet on floor, felt it. :-)

Lana Gramlich said...

The picture of the nymphs is amazing! Great shot!

Andrée said...

Oh come on! Just one! It looks like a bug we call leaf cutters. But common names are so poor for identification since they vary by different areas (even different families). I'll be looking for these. What's great is that you get things coming alive before me so I can try to find them here after looking at your posts.