A caterpillar mystery.

Here’s a case where I planted something with the vague idea that it happened to be a host plant for somebody interesting, and then that somebody interesting happened to show up.

I’ve been waffling on wild blue indigo (Baptisia australis) for most of two years now, because I couldn’t figure out where to put it and by all accounts it does not transplant well if you pick wrong. This spring I finally found a spot that I think’ll accommodate it really well, and the plant’s been doing great. It’s supposed to be one of those plants that just sort of sits there for forever while it quietly grows a massive root system belowground, and then shoots up all of a sudden a few years later, so I expect very little out of it for the near future.

7/21/17.

So anyway, I happened to be walking by a couple weeks ago and realized it was actually getting some attention from some guys I haven’t seen before.

I love the ones that make little leaf nests and stuff. It makes them ironically easy to find. 7/20/17.

First thing I do when I find a weird bug on a plant is go look for that plant’s page on Illinois Wildflowers, which I spend a ton of time on considering I don’t live anywhere near Illinois. It turns out most of our species occur in Illinois as well, and the “Faunal Associations” section for each plant is by leaps and bounds the most reliable source I’ve found for insect and wildlife relationships.

So these caterpillars are almost definitely one of two skippers: Wild Indigo Duskywing and Hoary Edge. The only way to know which one for 100% sure is to raise one to adulthood and see what pops out.

Except I’m impatient, man. I want to put stuff on my list, and I can’t do that until I’m positive of the ID. My first guess was hoary edge; they bear a decent resemblance to silver-spotted skippers, which are so common here I pretty much tune them out. I’ve only seen one other spread-wing skipper that I can recall, so I figured the wild indigo duskywing would’ve stuck out like a sore thumb.

But a couple days later I realized it was probably wild indigo duskywing after all, because I found them on another species entirely.

7/20/17.

This is columbine (Aquilegia canadensis), which I thought to check on based on some mentions I’d seen in my initial research. Columbine duskywings are a closely related species in the same genus that apparently look almost identical to wild indigo duskywings. Columbine duskywing, however, is not on my county species list. And wild indigo duskywings have apparently been recorded feeding on columbine as well.

Did a quick experiment to confirm and yeah, one of the columbine caterpillars is feeding quite well on wild indigo leaves. I’m keeping a few from each plant to see what happens when they eclose, but I’m pretty pleased with this ID.