Found these guys crawling on my fading pansies and used the caterpillar photos on DallasButterflies.com to identify them.
Judging from their photos, this is a Variegated Fritillary (Euptoieta claudia) caterpillar, which is in the same family with the Gulf Fritillary and the lovely Julia butterfly. I'm not sure this is the right food for them, but perhaps it was suitable. The pansies are all gone.
Looking forward to seeing the butterflies!