thanks Alan. Do you just remove the top or punch some holes in it when you're ready to use?
I punch a hole in the smaller vials - and have drilled holes in the caps of the larger cups.
A moist viv (obviously there is a span of degrees here) will soak coffee filter caps after a few days. So I adjust my approach based on how I keep my vivs.
Also - I don't want frogs getting into mischief trying to get into a vial/cup chasing flies.