The Very Hungry Caterpillar

I could see this little devil moving its head from side to side, and I could just about hear its little raspers going hell for leather at my lime tree.  It's going to be a moth of some sort, and I really really want to kill it.  But on the other hand I really really want to let it go and see what it grows into.

Most of the loopers I know are green, but this one is a bit different.

I think I'll wait a few days before sending it to meet it's maker - I'm sure it can't kill the lime tree in the meantime.  I hope.