Saddleback Caterpillar
The saddleback caterpillar is stunningly beautiful, but it is most likely to impress its presence upon you with a devilish sting. If you innocently brush against one where it hangs on the underside of a leaf, you will be punished with an intensely burning welt for several minutes at least. Perhaps you can forgive its cruelty as you marvel at its vivid color and otherworldly form.
The caterpillar’s common name refers to the brown, saddle-like blotch in the center of its rich kelly green back. Each end is capped with reddish-brown and bears a pair of imposing bristly “horns.” The head is moustachioed with additional spines and the tail end bears large white eye spots reminiscent of spiderman’s. Both sides of the abdomen are lined with yet more spines.
Saddleback capterpillar photo credit: N. Lewis
The saddleback caterpillar is the larva of a fairly inconspicuous brown moth. The species, Acharia stimulea (formerly Sibine stimulea), is native to the eastern United States. You are most likely to encounter the caterpillar in August and September. I have found them on roses, Itea, shrub dogwoods, and Carex, but they are documented to feed on dozens of common garden plants.
Nancy Yergin September 1, 2009 at 2:13 pm
It’s beautiful enough. I’m wearing gloves in the garden anyways.
What sort of critter eats IT?
Nicole Lewis September 2, 2009 at 6:07 am
I have also wondered what eats these but haven’t been able to find a thorough answer. I did learn (from a paper on the Ecological Society of America website) that generalist predators like assassin bugs and lacewing larvae prefer to eat non-spiny caterpillars, and paper wasps even learn through experience to avoid them. But that implies that they aren’t ignored 100% by those and other usual predators of caterpillars. Also, some species might PREFER to parasitize the stinging caterpillars because they are less likely to be eaten before the parasite babies get their fill and move on.
nelson carter September 3, 2009 at 7:56 pm
Thank you for the information.
I was on the stinging end of one yesterday and have been trying to find out it’s identify.
hoot October 25, 2009 at 3:57 pm
I was bite by one five times yesterday. I thought it was a thorn.
Nicole Lewis October 27, 2009 at 8:56 am
Ouch. I have brushed against one a couple times in a row, too, before I realized what it was. Thankfully they don’t “bite”, but the poison from those stingers feels at least as bad as a cut. I hope it was some consolation that it was more beautiful and interesting than a thorn.
Eldon Burr November 3, 2009 at 8:48 pm
I first encountered a saddleback caterpillar about 15 years ago, before there was an Internet to find out what it was. I finally found it in an insect book weeks later. It had a lot more bristles that the one shown in the photo above. An Internet search on the name will find you a photo of the bristly one. I merely brushed against it with my bare shoulder and it felt like I had been stung by 5 wasps, all at the same time. The skin died in a streak on my shoulder and took a couple of weeks to heal. These are bad bugs!
Nicole Lewis November 4, 2009 at 12:31 pm
Did it look like this?– http://www4.samford.edu/schools/artsci/biology/zoology/invertzoo-05f/pages/24.htm I have watched some captive caterpillars “grow into” their hairs, so when they’re young the bristles are much larger relative to the rest of their body. I wonder if the poison similarly dilutes as the whole body mass grows? I have been fortunate to never have any visible damage after the swelling goes down, out of the 6 or so times I’ve been stung. Perhaps some populations/subspecies are naturally worse?