Green frogs are one of Michigan's largest species, growing up to 6 in. long. They are widespread around the state where there are permanent ponds and can tolerate the widest variety of conditions of any anuran species. They have reportedly survived a dip in a highly chlorinated swimming pool. Often mistaken for bullfrogs, green frogs have a dorsolateral ridge that is absent in bullfrogs. Males can be distinguished from females by the size of the tympanum or eardrum. In males, the eardrum is larger than the eye; in females it is smaller than the eye.
Green frogs have the longest window of breeding, calling from May through July and even into August. The tadpoles take 3 months to mature and often over winter before metamorphosis, making permanent ponds crucial for their success.
The green frog call sounds like a banjo string being plucked.