Forest Preserve District of Cook County, Illinois
Nature Bulletins
Newton Home Page

Introduction and Instructions

Search Engine

Table of Contents



Common Snakes
Nature Bulletin No. 270-A   May 20, 1967
Forest Preserve District of Cook County
Richard B. Ogilvie, President
Roland F. Eisenbeis, Supt. of Conservation

Most grownups have a dislike or horror of snakes and regard them as loathsome, or dangerous, or both. Children, however, have a lively curiosity about snakes. Little tots handle them without fear, and any prejudices which older boys and girls may have acquired, from their elders and popular misinformation, can be easily overcome. Actually, snakes are clean and dry -- not slimy; most of them are harmless; and many of them are highly beneficial to mankind. There are few kinds of poisonous snakes -- only four in Illinois -- and, unless in wild isolated regions, there are none in most localities.

Garter snakes and some of the smaller kinds are frequently found under boulders or rotting logs or, even in the vacant lots of cities and towns, flat objects such as lumber, sheets of tin, or roofing material lying on the ground. The larger snakes are seldom encountered except by chance. Modern agriculture has greatly reduced their abundance by drainage of marshes and wet ground, removal of woodlands, and intensive cultivation which wiped out much of their natural prey. Many of them are killed by mowers or reapers, and by automobiles on the highways. Most of these are valuable, especially to the farmer, because they eat great numbers of mice, rats, ground squirrels, gophers and such rodents. Several of the smaller kinds prey largely upon insects. Others eat earthworms, frogs, toads, or fish and aquatic animals, but do little harm because such creatures are plentiful.

Some snakes, like the bull snake, pilot black snake, fox snake and king snake, kill their prey by squeezing it and are called "constrictors". The poisonous snakes kill with their venomous fangs. Others merely seize the animal in their mouth and gradually swallow it, alive and whole. Some kinds lay eggs and some give birth to living young. Usually, the young appear in late summer or early fall.

Of the 32 distinct species of snakes in Illinois, only 18 are found in the Chicago area and only six of these may be called "common"; abundant and frequently seen. Three others -- the Smooth Green Snake, the little brown DeKay's Snake, and its smaller relative, the Red-bellied Snake -- are probably abundant in many places but are seldom seen because they are so small, so secretive, and so well camouflaged. The Pilot Black Snake, the Fox Snake and the Bull Snake are all common, all lay eggs, and are all large. The Common Water Snake, the Queen Water Snake, the Common Garter Snake, and the Plains Garter Snake are very abundant, all bear their young alive, and all seize their prey in their mouths. The Hog-nosed Snake or Puff Adder, the Blue and the Black Racers, the King Snake, and the Milk Snake or Spotted Adder, are large egg-laying snakes which are less common. All those named here are harmless.

A snake is frequently hard for the ordinary person to identify. An expert identifies it by the color and markings, by the kind and number of scales on its back, and by the arrangement of the scales on its belly. Some, like the green snake and the racers, have a uniform color but the young racers are spotted and blotched. Some have longitudinal stripes, some have crossbands, and some have spots or other distinctive patterns. Their colors tend to darken as they grow older, and the markings become less distinct, although they are always brighter just after a snake sheds its skin -- which it does several times during the warm months. There may also be considerable variation in certain species.

Like a snake's tail, this is the end. Don't hiss!

To return to the Nature Bulletins Click Here!
Hosted by NEWTON

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Sponsered by Argonne National Labs