My friend Tara left her Monarch adults and pupae with me while she was off to NH for her dad's surgery. She also left many Black Swallowtail caterpillars. I butterfly sit for my friends. The plan was to keep the Monarchs and release after Hurricane Sandy. The weather here was cold after the hurricane, too. So I boxed them up and shipped them further south. Luckily, my son goes to college in Williamsburg, VA and he helped release them there. The people at the post office thought I was sending him a cake because I had called them to make sure he got the package right away. Not a cake, but butterflies he told them. Every butterfly counts!
There are pictures here that will show you how I boxed them for shipment.
You do not need a permit from the USDA to ship butterflies within your state, but you do need a permit to ship them across state lines.