Spined Soldier Bug, and its Doppleganger
Also in the August 23, 2012 sweep-net were a number of these brown stink-bugs with sharp spines on their shoulders.
This is one of the Soldier Bugs in the genus Podisus, which are predatory stink-bugs that are particularly fond of caterpillars. An how do I know they are predatory? Because I found one predating, here – it’s just finishing off a caterpillar of some sort.
In fact, it is quite likely that this is the adult form of the predatory stink-bug nymphs that we found raiding a tent-caterpillar nest just a couple of months previous.
Flipping it over, it has a creamy yellow underbelly with speckles.
And looking more closely at the mouthparts, we see that it has a stout, robust beak of the kind that we’ve seen on predatory true bugs, and is apparently good for punching through the chitinous shells of other insects and drilling into their flesh (as opposed to the thin, needle-like mouthparts of the bugs that suck juices from plants). If we look back above at the picture of one of these bugs eating a caterpillar, we can also see that the mouthparts are jointed, kind of like an arm, which simplifies the stabbing action.
I’m undecided as to which of the Podisus species it is. From above, it looks most like the very common Spined Soldier Bug, Podisus maculiventris, but the belly doesn’t look quite right.
Of course, when identifying these, one has to be careful. There are other types of stink-bug that are near-doubles of the soldier bugs in appearance, but are mostly unrelated and have completely different lifestyles. Like this one, which at the time I thought was another member of the same species (and so it didn’t get photographed as much as it should have).
Very close, but once I sat down to process the pictures, I realized that there are two noticeable differences. First, it doesn’t have the sharp spines on the shoulders. Second, the legs are pale with black spots, instead of being reddish-brown and unspotted. And, in this lousy blurry picture, we can see that the underbelly is pale green, not yellow.
If I’d had the presence of mind to flip it over and photograph the underside, I’d bet that we would have also seen the thin, needle-like mouthparts of a plant-juice-sucking bug. I expect that this is one of the stink bugs in the genus Euschistus, and may possibly be the very common Brown Stink Bug, Euschistus servus