Is my frog pregnant?

[Sanimal]

I have several questions about my two American green tree frogs. First of all, how do I tell what gender they are? I've heard that for males, the eardrum is smaller than their eye and for females it's larger. However, I'm unsure if this is true. They both croak; does this mean that they are both males? Do only male green tree frogs croak? I thought they were both males, until I noticed about two weeks ago that they were in the "amplexus" position. The smaller frog was on top of the larger frog and was gripping it under the two front legs. A few days later that frog was again in this position. This is the last time I saw them do it. A few months ago I noticed that another one of my frogs (which has died by now) was also in this position atop of the same frog (the larger one again). I actually didn't mean to breed them; I didn't do anything required to do so (putting them in a rain chamber, cooling their temperatures, feeding them heavily, etc.).

Another question I have is that the larger frog (which could be a female) has a bluish coloration inside its belly (not on the outside). I don't think it's eggs because she has had this for a while (I think for a few months now). If it isn't eggs, what is this? Is it just the internal organs slightly visible? Also, how long is the period of time from when the frogs mate until they lay their eggs?

Thank You!

Sanimal

[Kurt]

A horny male frog will grab on to anything, it doesn't have to be female or even the same species. If you want to find out whether you have a mated pair set them up in a rain chamber.