I’ve tried hunting for caterpillars among my native plants in the yard over the past several years, hoping to find some interesting caterpillars with very little success. This past weekend I was looking around my little prairie patch in the backyard with my UV flashlight and found something exciting. Two large caterpillars feasting on partridge pea (Chamaecrista fasciculata). It took me quite a bit of research to finally identify them as one of the Zale moths (Zale sp.) in the Family Erebidae. I am fairly certain this must be Zale lunata (lunate zale), but according to Wagner in “Caterpillars of North America” and “Owlet Caterpillars of Eastern North America,” Z. lunata and Z. minerea are nearly indistinguishable as larvae. However, because there are no records I could find of Z. minerea feeding on herbaceous plants and Z. lunata is known to feed occasionally on herbaceous plants, particularly those in the pea family, I think it is a safe bet to call these Z. lunata. To test this for certain, I hope to be able to find them again and try rearing one to an adult, which are easy to distinguish between these two species.
15-August update:
A couple of nights after taking these photos, I visited the prairie patch and found four of these zale caterpillars. I collected one and put it into a flight cage along with some freshly cut partridge pea.
After not being able to find the caterpillar for the past two days, I finally discovered that it had pupated and has used some of the vegetation to cover its cocoon. There’s a chance it might eclose this year. If not, I’ll have to wait until the spring, assuming it survives that long. Here’s a photo of its pupation site.
28-August update:
Upon returning from work today, I found that my Zale had eclosed! I took a few photos and I think we can now definitely say this is Zale lunata.
A Thousand Acres of Silphiums 
A very impressive backyard find, Bill. I had to look up this species.
Thank you Miguel! Yes, the adults are very striking.