What kind of treefrogs? I have raised pacific treefrog tadpoles in plastic shoeboxes and have some new morphs in a plastic critter keeper. It is easy to put pantyhose over the top of the critter keeper when i feed them fruit flies to try to keep most of the flies around so the frogs can eat them. Moving them into a larger tank is a good idea though. You cant really put an undertank heater or heat or uvb lamp on a plastic tank. Depends on what type of frog, how large, how many in a container, etc.