The spring peeper averages three-fourths to one and one-fourth inches in length. It has a dark, irregular, x-shaped mark on the back and a dark mark between the eyes. The body color is yellow, brown, gray or olive with a pink cast. A small adhesive pad is present at the tip of each toe.
The spring peeper may be found statewide in Illinois. This small anuran lives in moist woodlands. It is seldom seen except when breeding. It lives in trees or on herbaceous plants. It is usually active at night. Breeding occurs from early March to early June. The male’s call is a soft, birdlike whistle. The female deposits several hundred eggs singly, attaching them to submerged objects. Hatching occurs in a few days with transformation to the land-based form being completed in May and June. The spring peeper eats small arthropods (spiders, insects, mites and others).