These are really easy to rear through,rather than them going to waste. They will hatch in about 10 days and start themoff on the smallest and freshest sallow leaves. Keep them in a small plastic container, remembering to replace leaves and throw out the frass every day. Don't believe the hype that they will eat bramble and hawthorn once they've tastest sallow, they won't want anything else and will even go on hunger strike! Once they kick in properly you then become their slave. Boycan these guys eat and they rip through their instars to finally spin and pupate on the sticks you have been recently bringing back from the upper reaches of the local sallow, as that's where the freshest leaves are, they've become your pets and they've told you to climb that high for you! They are a beautiful caterpillar series to go through, relatively easy, a tad less demanding than the wife and you can always release the adults from the back of your garden as, from there, is where they originated. You'll loose about 25% caterpillars naturally, spray them with water once a week just to remind them about the real world and once pupated, stick them in sheltered position in the garden some where so the poor loves don't get too much of it. Come early April cut the thick cocoon gently with a pair of scissors and place them again in a plastic box keeping an eye out for them to emerge and then release. Simple, eh? Good luck.