What can they do at the hospital if you go in for really bad bug bites?

Depends: If you get poisoned by certain spider bites, life support may be needed (brown recluse, black widow ). On the other hand, infection is a real issue from spider bites. Bee stings is yet another issue. Secondary infection of the bites may also need to be addressed. So there are many potential answers depending on the type and the extent of the bites.