Subject: Spiky caterpillar,
Location: central MO, USA
April 28, 2014 7:03 pm
I took a picture of this caterpillar in early September 2006, he was on my tomato plants… I plucked the leaf he was on and put it on a chair so I could try to figure out what he was… never did find out. Here’s the picture, It looks similar to the Mourning Cloak Caterpillar which is on here, but different enough that I think it is a different caterpillar, maybe the spiny elm caterpillar?
You actually got quite close with your identification attempt. We believe this is the caterpillar of a Questionmark, Polygonia interrogationis, a butterfly in the same tribe as the Mourning Cloak, Nymphalini. You can compare your image to this image from Bugguide. Are you growing hops in your garden? According to BugGuide, the “Caterpillars feed on nettle, false nettle, elms, hackberry, Japanese hops.”