Reaction

It appears that many caterpillars within Acronicta are mimics of other caterpillars. These relationships have yet to be investigated beyond comparing superficial resemblances. This is something I hope to tackle with my own research.

For now I’m still raising some caterpillars for general life history data, waiting for them to pupate so I can get on with my life and have a little break from cleaning frass until the spring.

One species in my care is Acronicta impleta. It is supposed that this species mimics caterpillars in the family Lymantriidae. They have very similar tufts and coloration. Here is A. impleta

trying to look a lot like a Dasychira species

(image from BugGuide)

Many lymantriid caterpillars sting, so they would be a good group to mimic. Just look at all those nasty spines and tufts. A. impleta also has some other color variations, including a predominantly orange morph.

According to my advisor, A. impleta is most likely a harmless Batesian mimic. But today, while cleaning their containers, one brushed against my hand. It stung a little bit.

So being curious, I rubbed it against the back of my hand. AHHHHH!!!!

My skin turned red, I started getting little white spots around the sting site, and the reaction spread across the rest of my hand. It all had a low burning sensation, and lasted for about an hour (even after applying benadryl cream)

I asked my advisor and some fellow students to experiment on themselves, and while they happily obliged, none of them reacted. Perhaps I am just extra sensitive to this species or the physical hairs themselves? Or is there something chemical going on here? I would love to test this! Perhaps it is Mullerian mimicry and not Batesian if the A. impleta are themselves protected?

That was my excitement for the day.

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Posted on September 28, 2011, in Acronicta, Acronictinae, Invertebrates, Lepidoptera, Noctuidae. Bookmark the permalink. 9 Comments.

  1. I took a photo of an Acronicta dactylina the other day. Is it a mimic, too? There wasn’t much said about it in my guide book.

    • I haven’t raised that species yet, but it appears to resemble an arctiid. A lot of what is called mimicry within the Acronicta is just conjecture based on their appearances, the ecology and chemistry hasn’t been worked out yet. I’m about to post an update – I still have a rash from A. impleta!

  2. Very interesting. If I recall correctly, the toxins are in hollow hairs of some urticating caterpillars and are delivered when the tips of the hairs break off. Did you use the same caterpillar on yourself for the other tests? If so, then possibly the venom was depleted.

    Acronicta oblinita caterpillars are pretty common here in the late summer, brightly coloured and in exposed positions – as if they don’t worry about birds. I guess I will be careful if I get the urge to pick one up.

    • I raised many oblinita this summer and did not get any reaction, but I mostly held them in my hands and did not purposefully rub them on the sensitive skin of the back of my hands or arms. Next year I will try!

  3. I am allergic to insect venom – your little bug there would cause exactly the same reaction with my hand.

  4. I just revmoed 15 of these little %#*&@ blankety blankety suckers from my three heirloom plants! FIFTEEN! They eat the leaf life similar to the way you eat corn off the cob. Very fast…celan…and very gone! FYI: The post about not eating fruit may not be accurate. I took all 15 of these guys placed them on garbage can lid in the sun for the birds to find. I also placed four damaged green tomatoes in the lid. Have gone back periodically to check their demise…and several are consuming the already gnawed on tomatoes. So…they WILl eat the fruit! I assume the odd damage on my tomatoes is indeed from them!The hardest trick is seeing them on your vines. They are sloth like. Don’t move fast…and are the same color are your plant. You have to get real still, and stay focused on what your eyes are seeing. And then VIOLA! Your efforts will be rewarded when you see one! Usually hanging underneath the leaf or limb protected from the sun rays.Here is my experience. The leaves are missing. The stalk, trunk or limb is all that remains…there are black poop droppings on some leaves…these are all the signs of the ellusive HornWorm. If you see any of these…get out your patience and hunt them down!Hope that helps any future readers!

  1. Pingback: 5 days later « caterpillarblog

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