I have some caterpillars, and i want to make a mush out of leaves to feed them. how can i do this?

i have luna moth caterpillars, and i remembered the mash you can get whn you but silkworms. i thought "i should make a mahs like that from sweetgum tree leaves, but i haveno idea how. the leaves i give them wilt too fast. any ideas on how ti make a mash?