What to do if you step on a poisonous catterpillar?

Butterflies can not bite people, they have probiscus's which means they have a long tongue which is used to drink liquids of nectar from flowers, so they have no jaws to bite people, nor do they have any stingers to inject venom, although few species of butterfly are poisonous to be eaten and their claws could scratch you very lightly. As a result, butterflies don't bite, so there is no remedy for a problem which doesn't exist.