You get a friend with pipevine to mail you pipevine leaves. The leaves keep fresh in a ziploc bag in the fridge. I raised my PVST cats on nothing but Priority Mail pipevine leaves since I have no pipevine and the cats would not eat my wild ginger.

I have no idea how nourishing it might be, but I've seen those kind of late-instar cats eat certain kinds of pipevine plants to the ground and even eat some on the immature seed pods. Piggies...that's just their nature! I've got 14 cats left now and am close to running out of foliage for them...at least they're all 5th instar cats! Now, why can't the PVST mothers do what the Giant Swallowtail mother(s) in the area has done this year...just 1 or 2 eggs at a time, then I don't see any more for weeks! Just sayin'...!

That is a big problem, isn't it? That happened to me with some Spicebush cats a few years back. My Spicebush plants were too small to support them to pupation, so I took them out to the wild and put them onto some Sasafrass. I would imagine that if they run out of food and can't find anymore Pipevine close by, they would just die. KC has a great idea there, and I wish I had thought of that back when.

Depends on the hostplant and/or caterpillars whether my suggestion works. Some leaves won't hold up. Some caterpillars demand fresh food.

I've fed refrigerated common milkweed leaves to monarchs since the early '70s. Dutchman's pipe worked well last year. Other attempts have failed. Lunas and polys would not eat refrigerated English walnut.

Thanks everyone. I didn't even think about moving them to another plant. (duh!). They didn't run out this time, but it got close. I do have another plant growing up the chicken run that they haven't found yet..........so that definitely would have been a possibility. I'm surprised a pv swallowtail hasn't found that one yet. Although it does give it a chance to grow bigger, before one does find it.
Thanks!

Pipevine leaves do indeed hold up well in water in a refrigerator. I did that one time, can't remember when or why, just that they ate and grew on them.

Sherry