This week’s puzzler is a Green Frog, not to be confused with a green frog, as many of them are! Green Frogs are one kind of frog, just as Bull Frog or Wood Frogs are two other kinds of frogs. Green Frogs happen to be green, like many other frogs, which only makes it all that much more confusing!
Green Frogs are often and easily confused with Bull Frogs but once you know the difference, it will be easy to distinguish between the two. Green Frogs have what is called a dorsal lateral ridge that runs down the sides of their bodies, from their eyes backwards. Bull Frogs lack this ridge. The top photo is a Green Frog and the one on the right is a Bull Frog. 
You can tell the sex of some frogs by looking at the circle just behind their eyes. This is called the tympanum and is a membrane that covers the hearing organ, or ears of the frog.
In males the tympanum is LARGER than the eye. In females, the tympanum is the same size or smaller than the frog’s eye. So the Green Frog above is a female and the Bull Frog to the right is a male.
So now you know! Next time you see a frog, look for the tympanum and determine whether it’s a male or female.
Oh, and for the record, there is a mosquito biting the Green Frog’s butt in the top picture!