I've never seen anything like that on a tiger swallowtail cat or any other cat, for that matter. 'Wonder what it is? Parasitized by something? Fungus?

Sherry

I've never seen it either. It looks so wrong, so that's why I euthanized. (freezer method)

He looked a little skinny too. I don't know if he was one of the eggs or caterpillars I brought in. The other ones look fine. I'm leaning towards parasite.

Update: I went back out to my wafer ash, and there was a tachinid fly sitting on a leaf :(

I suspect it laid eggs on/in that poor caterpillar. Of course now I'm worried that a tachinid could have gotten in my house too. I guess it's better than having chalcid wasps though....

edit: So maybe not a tachinid fly infection - I didn't find any photos on the web that looked like my caterpillar. So frustrating - I think I'll try to find an entomologist and email them.