For Blake's birthday he got a Bugville Butterfly house. You send away for some larva, they come in the mail, then they grow through their life cycle and when they emerge into butterflies, you let them go.
We got our little cuppy with 5 little caterpillars last Saturday. They have all the food they need in this cup (all the brown spots), so you really don't have to do a thing, except make sure they don't get too hot or too cold. This week we have woken up every morning to find that they have grown bigger and bigger and bigger. This morning it looks like they are working their way towards making their cozy cocoons. When they are all in their cocoons, you move them to a butterfly house made out of netting until they come out all metamorphosised.
We'll keep you posted!