[David]

I think most probably the frogs were trying to steal insects that were attracted to the pitchers. If so, it's a beautiful symbiosis between the nep and the frogs.

I have not seen frogs on my neps before but I have seen pictures of frogs in the pitchers in the wild, just sitting there waiting for an insect to drop in. There are also accounts of fresh water crabs going into the pitchers in the wild.