I tend to "free feed" all of my amphibians. That is, I have enclosures set up to just turn the food items loose in the tank and watch the show. It never ceases to amaze me how large of prey frogs will take on. I believe the term is "gape limited predation", meaning they will eat anything they can cram in.

I have found though with tree frogs anyway, that night is best to feed them, if they are "sleeping", they will eat when they are ready. I also found they quickly become obese if you do not carefully control how much food they have access to. believe me when I say there is nothing more sorry looking than an obese amphibian. (The frog I mention here is on a diet, but it may be some time before he is back down to his "fighting" weight...)