ORGANIC gardening in PENNSYLVANIA
Monarch caterpillars will eat any Milkweed.
Turns out that this probably isn't milkweed. :( There was no sap when I popped off the leaves. Plus my monarch cats wouldn't go near it. I found some milkweed at a local creek, and they are devouring it. It was such a relief. They were barely eating any of the A. tuberosa that I harvested fresh from my garden. All is well now. They are well fed, and I can stop worrying about them. :)