The northern leopard frog averages two to three and one-half inches in length. Its body is brown or green. Two or three rows of dark spots are present between the dorsolateral folds. The spots are rounded with light borders. More spots are present on the sides. The vocal sacs of males are only visible when calling. There is a dark spot on the snout. The dorsolateral folds are light-colored and continuous to the groin area.
The northern leopard frog may be found in the northern one-half of Illinois. This amphibian is sometimes called the “meadow frog” because in the summer it is often found well away from water. It lives in marshes, streams, ponds and lakes. The northern leopard frog is a wary, alert, excellent jumper. It may scream when grabbed by a predator. Breeding occurs mid-March through May in ponds, lakes, sloughs or ﬂooded ﬁelds. The call of the male may be imitated by rubbing a thumb across an inﬂated balloon. The female deposits about 3,000 to 5,000 eggs in three- to six-inch spheres that are attached to submerged vegetation. Hatching occurs in about 10 to 14 days. Transformation to the adult form occurs June through August. The northern leopard frog eats arthropods (spiders, insects, mites and others), mollusks (snails, slugs and others) and annelids (earthworms, leeches).