I hate for anything to suffer and I hope I didn't cause these creatures to. Once, I captured a huge black widow out in the yard with the intent of preserving it as a specimen for the boys. Pouring alcohol on it was supposed to kill it immediately, according to my entomologist friend. Well, I poured the alcohol on it and it swam around frantically for what seemed like forever. Probably just a minute or two at the most. I was mortified. Then I found out my alcohol wasn't 70% like normal, but cheap 50% and that's probably why it didn't kill it right away. I felt really bad about that.
The kitchen window may actually be to blame. Tadpoles live in dark and COOL water. We could never get them to turn into frogs inside either, but they grew up fine outside. Used to capture them from the neighborhood pond. I think it is too warm (and maybe too bright) in the house. Try it again outside with local native frogs, and then the frogs can hop away when they are ready. Pond building experiment!