Fig. 7 - The copperhead, Ag kistrodon contor- 

 trix. This snake, found in the southern half of 

 Illinois, is common only in wooded, rocky areas. 

 The specimen pictured here shows signs of injury 

 on the back. 



of southern Illinois where poisonous species are 

 likely to be a real danger, the presence of snakes 

 is much less alarming to the residents. Possibly 

 this situation exists because where snakes are 

 common the residents recognize the venomous spe- 

 cies on sight, or it may be an illustration of the 

 old adage that familiarity breeds contempt. 



Four species of poisonous snakes, the timber 

 rattler, the massasauga or swamp rattler, the 

 copperhead, and the cottonmouth or water moccasin, 

 are known to occur in Illinois. Figs. 1-4 indicate 

 where venomous species may be found in the state. 

 The danger of encountering poisonous snakes is 

 actually less than is suggested by the maps, since 

 many Illinois counties are included within the range 

 of one or more species even though such snakes 

 may have been exterminated from these counties 

 many years ago. 



There are infallible methods for distinguish- 

 ing venomous from harmless snakes occurring in 

 Illinois, but none of these methods is very help- 

 ful to the average individual unless the snake is 

 dead and can be examined closely. Poisonous 

 snakes have (1) large, movable, hollow fangs and 

 venom glands; (2) eye pupils vertically elliptical 

 like those of a cat; (3) a pit on each side of the 

 head between the eye and nostril; (4) scales under 

 the tail just like those on the belly. Nonpoisonous 

 species have (1) teeth, but they do not have large, 

 movable, hollow fangs and venom glands; (2) round 



eye pupils; (3) no pit on the side of the head; (4) a 

 double row of plates or scales under the tail and 

 a single row on the belly. The size and shape of 

 the head are not good characteristics for distin- 

 guishing poisonous from nonpoisonous snakes. 



The most practical method for distinguishing 

 the venomous snakes from the nonpoisonous con- 

 sists of learning to recognize the local venomous 

 species by the color pattern. This is done simply 

 by examining pictures of these animals and memo- 

 rizing the characteristic pattern features. In the 

 northern half of Illinois, it is safe to assume that 

 any snake that does not have a rattle is harmless. 

 Three of the four poisonous snakes of Illinois are 

 shown in figs. 5-7. The fourth, the cottonmouth 

 or water moccasin, is shown on the cover. 



Even in an area harboring poisonous snakes, 

 there is little danger of snake bites for the person 

 who takes a few simple precautions. (1) Recognize 

 the poisonous species. (2) Always watch where 

 you step and where you place your hands, particu- 

 larly in rocky country where copperheads and timber 

 rattlers occur. Almost all snake bites occur either 

 on the hands or on the legs below the knees. (3) 

 Carry a flashlight or lantern at night. All the Illi- 

 nois poisonous snakes are nocturnal. (4) Do not 

 handle venomous snakes. A high percentage of the 

 snake bites in this country result from people 

 capturing or otherwise handling these reptiles. 



Snakes Believed to be Poisonous 



Many nonpoisonous snakes are mistaken for 

 poisonous species. These are the southern milk 

 snake, fig. 8, the common water snake, fig. 9, 

 and the fox snake, all of which are commonly mis- 

 taken for the copperhead; all species of water 

 snakes that superficially resemble the water moc- 

 casin; and the large terrestrial snakes that vibrate 

 their tails when alarmed and are therefore mistaken 

 for rattlesnakes. There is a possibility that the 

 southern milk snake might be mistaken for the 

 poisonous coral snake, which it somewhat re- 

 sembles. The coral snake probably does not occur 

 anywhere near Illinois, however, and the milk 

 snake is too uncommon to create much alarm. 



Some nonpoisonous snakes are reputed to be 

 dangerous, even though they are not mistaken for 

 rattlesnakes, copperheads, or cottonmouths. The 

 two species of hognosed snakes, one of which is 

 shown in fig. 10, are often dreaded. These snakes 

 are known also as "spread-heads" or "spreading 

 vipers." Despite their impressive appearance and 

 threatening behavior, these snakes are harmless 



