I planted two black willows last year - one in my garden and one outside it - in hopes of getting viceroys. I haven't raised any viceroy caterpillars since well before the hurricane (2005) and haven't even seen an adult in about ?two years - I saw one in late fall a couple of years ago. Still, if you don't plant willows, you can't expect to increase the population, so I planted the one outside the garden in a hole near the well, with a thick leaf mulch covering the space between the top of the plant and the surrounding soil - I keep it wet at all times. I planted the one in the garden a little lower than soil level and keep it equally as wet. I figure if the garden willow gets too big, which it undoubtedly will, I can always prune it.
I found six red-spotted purple eggs on the one by the well - red-spotted purples usually use wild black cherry, but they'll occasionally use willows and crabapples. I was going to leave them there to raise themselves, but when one disappeared, I brought them in to raise myself. I've always had trouble keeping willow fresh in a water pick, so I put very small branches in small containers of water with a hole punched in the top and put all this in some little plastic containers (about 9" tall X 6" in circumference) with a vented top. I figure this would keep the willow more humid. Well, it worked! The leaves stayed turgid the entire time the cats were eating them, wonderful! These cats pupated early - I wondered if maybe willow leaves were less nutritious than the usual wild black cherry leaves and would make smaller red-spotted purples. Three of the cats pupated on the ceiling of the little containers and two pupated on a willow branch. I put the branches in water picks and put them in the big chrysalis cage, and I laid the lids against the side of the cage. I saw what looked like a butterfly on one of the lids this morning, from a distance it just looked smallish, so I figured it was a male red-spotted purple. You can imagine my surprise when I approached the cage and saw that it was a viceroy!! I never saw the Mama, so it never occurred to me that I had gotten so lucky!
I looked up the usual sizes for adult viceroys as compared to red-spotted purples, and my Audubon field guide lists RSPs as being 3"-3 3/8" across, but I've released some that I'm sure were 4" or more, undoubtedly females. Viceroys are listed as being 2 5/8"-3" across. This butterfly hasn't opened his/her wings for me, but I'll guess it's under 3" across. There is a smallish RSP that also emerged this morning in the chrysalis cage with it.
Hopefully, I'll be able to get a picture.
Words can't described how pleasantly surprised I am!