Predatory Stink Bugs Raiding Tent Caterpillar Nest

2012 December 8

On May 20, 2012, we were out in the yard looking at the resurging population of tent caterpillars on the little chokecherry trees that grow there. And on one of the tent caterpillar webs, we saw this bunch of young toughs hanging around, looking to cause trouble:

These are pretty obviously predatory stink bugs in the subfamily Asopinae, and they resemble some that I’ve posted before. They’re nymphs, as is clear from the fact that they don’t have any wings. Here’s one that’s just finished one victim (corpse in lower left), and is heading for another with its switchblade-like proboscis out for the kill:

As it turned out, though, it didn’t make the kill. Once it got close, the caterpillar started lashing its head back and forth, pummeling the stink bug until it decided to go off looking for something easier. Still, the stink bugs had obviously been successful before. Here’s one licking out the remains of a dead caterpillar while two others look on:

And here’s the trail of corpses.

The stink bugs weren’t the only predators around; there were also a few ants looking for whatever they could grab.

Overall, it looked pretty bad for the tent caterpillars. And when I went back a couple of days later, the web was empty of all except dead bodies. So, it is clear that while the webs may be a decent defense against some predators, they are not much help against the roving stink bug gangs.

Note added later: We raised some stink bug nymphs like these to adulthood, and they turned out to be Podisus placidus, which I’ve taken to calling “Webworm Destroyers”.

6 Responses
  1. December 8, 2012

    Nice post. Stink bugs parading as assassin beetles. Gotta love that. Thanks for your blog. I like it!

  2. Carole permalink
    December 8, 2012

    Great post. I always confuse the predatory stinkbugs with the ones that attack plants and seeds. I heard one holds its proboscis flat against the body and one is curved away from the body. I’ve also heard the shield shape is different.

  3. December 9, 2012

    NRG- Thanks!

    Carole – To be honest, so far the main way that I can tell that a stink bug is a predatory type, is when I catch it preying on something. Otherwise, as you suggest, all stink bugs look a lot alike. I’ve got a few more stink bugs in the queue of photos waiting to be processed, so maybe I’ll be able to confirm the proboscis thing when I get to them.

  4. December 9, 2012

    I wonder if the tent caterpillars draw predators to eat them which draw predators to eat the predators. If I were a creature that ate stink bugs, the tent caterpillars would make an excellent bait for my prey.

  5. December 10, 2012

    This is so cute and accurate a pin up notice for your first photograph that I had to laugh:

    we saw this bunch of young toughs hanging around, looking to cause trouble:

    They do look like teenagers out for a lark and fairly doubledecker bus tough.

    Then the neat little killer line (literally so in this case) :

    Here’s one that’s just finished one victim (corpse in lower left), and is heading for another with its switchblade-like proboscis out for the kill:


    I must say this post is very accurate and entertaining.

    I do agree that the little thug in the second photograph seems rather Mafia-like in the way that he is approaching his victim but then he is being confronted by a whiplash of a prey isn’t he? I guess he is getting his nerve up to go grapple with the massive bulk of that caterpillar fur-coat.

    The “trail of corpses” feels very war like and epic.

    That ant (in contrast to the stink bug thugs) seems rather elegant and scientific in the perusal that he made of the killing fields. Or maybe he was simply trying to hang on for dear life to the meshworks of the webbing under him?

    Who knew that life and death was so close to home in such genocidal proportions?
    Here I was thinking that only the tailings ponds in the tarsands in Alberta were the source of global death and destruction for all life forms and you have managed to expand this rather narrow perspective of annihilation to include stink bug manifestations of species eradication.

    I wonder if all the ladybugs that I have been admiring on my sunflowers every summer are really stink bugs?

    I will ignore this possibility as I like the idea of having ladybugs rather than killer marauders assassinating every caterpillar around.

    Now if these stink bugs only could do the deflating business with slugs around my Petunias.

    Can you try an experiment next time you get a group of these delinquents around and plop a fat slug near them and see if they would be good for biological warfare against the slug infestations I have in my backyard that cruelly deplete my Petunias that are unwilling victims of these predators—- being stuck as they are as potted food in clay pots?

    Let me know if they are good deterrents and I will be able to save my Petunias.

  6. December 10, 2012

    KT: It’s possible. The only question is what routinely eats stinkbugs. They are evidently pretty noxious. Back when we had a pet praying mantis, we’d go out and catch random insects for it to eat, and the stink bugs were the only things it wouldn’t touch. I expect that there are some parasitic wasps that come after them, though – there seem to be parasitic wasps that attack just about every common small arthropod.

    Julie: I expect the predatory stink bugs probably eat slugs given a chance, but I’ve read that the best slug-killers are ground beetles (the large, black, fast-moving beetles that are often found under rocks and boards). You can encourage ground beetles to hang around your garden by laying bits of board flat on the ground, which gives the beetles a place to hide out during the day. Of course, until the beetles show up it also gives the slugs a place to hide out during the day, so it is worthwhile to check under the boards every week or so to make sure they aren’t turning into slug havens.

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