Some Facts About ILLINOIS SNAKES and Their Control 



PHILIP W. SMITH, Assistant Taxonomist, Natural History Survey Division 



Thirty-five distinct species of snakes are 

 known to occur within Illinois. Some of these spe- 

 cies consist of two or more subspecies; including 

 all the subspecies there are 50 different kinds of 

 snakes in the state. A few subspecies are strik- 

 ingly different from closely related subspecies; 

 others differ only in such minute details as number 

 of scales on certain parts of the body or in arrange- 

 ment of head plates. The number of kinds recog- 

 nized by the observant person who is not a 

 specialist is likely to be between 35 and 50. Only 

 four Illinois species are poisonous. 



Despite a similarity in body form and method 

 of locomotion, the snakes- of Illinois are an ex- 

 tremely diverse group. Some species occur in 

 every county; most, however, inhabit only limited 

 portions of the state. Some species prefer prairie 

 regions, some forest, and still others forest-edge 

 or other brushy places. Some have distinctive 

 adaptations for swimming, climbing, or burrowing; 

 others do not. They range in size from the 10-inch 

 black-headed snake to the 7-foot bull snake. Some 

 kinds bite viciously; others cannot be induced to 

 bite. Some lay eggs; others give birth to young. 

 Some feed on only one or two other kinds of ani- 

 mals; others eat almost any animal they can 

 swallow. 



Credit Side of Snakes 



Snakes have long been a persecuted animal 

 group. Within the past few years, however, there 

 has been a noticeable and commendable change in 

 attitude toward these animals among farmers and 

 other persons who have realized their economic 

 value. 



The most obvious service of snakes to man is 

 their predation on destructive rodents. At least 16 

 kinds of Illinois snakes feed primarily on such 

 pests as mice, rats, and ground squirrels; accord- 

 ingly, they deserve protection. Their fondness for 

 small mammals is indicated by the frequency with 

 which racers, bull snakes, king snakes, and rat 

 snakes are seen in old buildings, under grain 

 shocks, and in other places favorable for rats 

 and mice. 



Twelve other kinds of Illinois snakes, mostly 

 small species, feed on invertebrate animals, in- 

 cluding insects and their larvae. The value of 

 these snakes is difficult to measure because many 



of them also feed on such beneficial animals as 

 spiders and earthworms. The best known of these 

 snakes are green snakes, brown snakes, ring- 

 necked snakes, and worm snakes. 



Approximately 10 aquatic species of Illinois 

 snakes feed primarily on fish and frogs. They 

 have been accused of competing with fishermen for 

 desirable fish. Water snakes usually take the most 

 readily available fish and thus tend to catch the 

 slowest swimming kinds, which are least desirable 

 to sportsmen. It should be pointed out that some 

 fisheries biologists believe that, to improve fish- 

 ing, predators should be encouraged rather than de- 

 stroyed. Natural "cropping" of the fish population 

 has been shown to result in rapid fish growth. 



At least eight of the Illinois species of snakes 

 mentioned in preceding paragraphs feed on other 

 snakes; four of these are known to destroy poison- 

 ous species. 



Debit Side of Snakes 



Although fish-eating snakes probably do little 

 or no harm to fish populations of lakes or streams, 

 they might conceivably cause considerable damage 

 in a fish hatchery, where small fishes are concen- 

 trated. 



The larger Illinois snakes, which are effective 

 rodent destroyers, occasionally take birds and their 

 eggs. Ground-nesting birds suffer the greatest 

 loss. A few kinds of snakes climb readily and thus 

 can prey upon birds that nest in shrubs and trees. 

 However, as stomach analyses have shown, rodent 

 destruction outweighs the predation on birds. 



Most people can trace their principal objection 

 to snakes to the fact that they have a deeply in- 

 stilled fear and dislike of these animals. Even 

 though they know a" snake to be harmless, they 

 find it startling to step on or near a snake. Many 

 persons can dispel this prejudice toward snakes 

 by learning something about them. They may even 

 find snakes fascinating animals once they over- 

 come their fear. 



anger of Poisonous 



Snake 



In some rural areas where reptiles are uncom- 

 mon, many of the residents have exaggerated fears 

 of snakes. They may even believe that all large 

 snakes are poisonous. In other areas, as in parts 



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