August 15th, 2006
danger, will robinson!
In the comments that followed yesterday’s update on the Monarch caterpillars, I once again made mention of predatory Stink Bugs. I guess a post about them is long overdue, so today’s the day.
Stink Bugs (Family Pentatomidae), belong to the Order Hemiptera, commonly referred to as the True Bugs. Hemiptera means “half wings” and describes the often thicker forewings that cover the membranous hind flying wings. They also have mouthparts which are beak-like, for stabbing into and sucking juices or fluids from either plants or prey. Some feed on plants, while others are predatory and feed mainly on other insects. The common name “Stink Bug” refers to a stinky fluid which these insects can discharge. I have a photo somewhere in my gadzillions of insect photos, of a droplet of the fluid falling from a stinkbug that I was photographing. Unfortunately, it would take awhile to find it, so you’ll have to either imagine it or go out and find a Stink Bug to see for yourself.
While a large number of Stink Bugs feed on plant juices, there are quite a few species that feed on the body fluids of insect prey. Most predatory Stink Bugs that I’ve photographed are species of Podisus (Soldier Bugs) which tend to have very sharp projections from the thorax (pointy shoulders), as in the above photo. Or they are species of Brochymena, which are gray, pebbly surfaced, and well camouflaged to resemble the tree bark where they commonly hunt. I’ll post some photos of Brochymenas sometime in the next few weeks when they begin to be frequently seen around the farm.
I often encounter predatory Stink Bugs while searching for Monarch caterpillars. I’ve posted a thumbnail photo of one on the left (just click on it for a larger view if you don’t mind a typically ghastly sight from the not-so-pretty face of the insect world). With this summer’s focus on the Monarchs, I’ve discovered just how rare a thing it is for the caterpillars to evade predatory Stink Bugs and similar “hunters” such as the Assassin Bug. If I find even one of either of these insects on a Milkweed plant, it’s very rare for me to find any living Monarch larvae on that plant or any of those within several feet. I believe they are very efficient hunters, especially the Stink Bugs, which seem to be constantly on the prowl.
While not much remains of small caterpillars killed by Stink Bugs, it’s not uncommon to find the blackened body of a larger caterpillar draped among the Milkweed leaves (again, just click for a larger view if you don’t mind such sights). Apparently, larger caterpillars are no match for the stalking Stink Bug.
Predatory insects such as Assassin, Ambush and Stink Bugs are considered to be among the “beneficial” insects — those that will hunt for crop-destroying prey — but it must be remembered that they don’t restrict their hunting to the less-desirable prey. Most will hunt down and feed on just about anything they can capture. For example, Ambush Bugs (Phymata) capture many pollinating insects such as Honey and Bumblebees. Apparently, they aren’t much liked by beekeepers. Similarly, a Stink Bug may be a big help chasing down Cabbage worms in the vegetable garden, but seems more like a nasty marauder when it’s hunting for Monarch caterpillars in the Milkweed patch.
Tags: Stink Bug, Podisus, Pentatomidae