certain other snakes have dens in rocks, in which they hibernate during the 

 coldest part of winter. . At times large numbers of snakes congregate in a 

 single cavity, where they pass the vjinter. References are found in litera^ 

 ture to "bundles" of snakes found by vvorkmen blasting in regions underlaid 

 by a rock formation. Various species burrow in the soil to escape the cold. 



Except pertain species adapted to extremes in aridity, snakes, espe- 

 cially the' subaquatic types, succumb also to intense heat. It has been re- 

 ported that even the rattlesnakes that frequent the I'ohavG Desert cr-n be 

 killed by 20 minutes' exposure to the direct rays of the midday sun, A 

 number of snakes estivate, suspending their noria'l activities during the 

 hottest part of summer. 



SHEDDING SKINS 



All vertebrates slough off the endderrnis from time to time» In hu- 

 man beings the change is gradual and imperceptible; other' m-'^ummals, as rab- 

 bits, mice, and squirrels, change their hair in spring and fall; the "molt" 

 of birds is well known. In the case of snakes, the entire epidermis, includ- 

 ing that covering the cornea of the eye, is sloughed off whole. 



The process of sloughing starts at the jaws, and the snake gradually 

 crawiks out of the cast-off epiderm.al layer, 'The length of time between sucr- 

 cessive slough varies. In captivity some snakes shed about every month 

 even during the coldest part of winter. The frequency of sloughing varies 

 with different individuals and possibly in the ssune individual at different 

 ages. Prof. Samuel Garman reported that a large king snake in his nosses-^ 

 sion shed its skin in April, Jnly and December, as did its mate in March, 

 May, August and October, These snakes were kent in a room throughout the 

 year. 



Or£J4.narily, about two sloughs are cast in a season, one v/hen' the snake 

 come* out of hibernation in spring and another about midsummer or later« 

 A young and growing snake, however, sheds its skin more frequently. The 

 milky appearance of the cyi^s of a snake shortly before the slough is cast 

 is due to the separation of the outer layer of epidermis from the cornea, 

 resulting in impaired vision. This gives rise to v-.rious superstitions re- 

 garding snakes going blind during dogdays,. 



ECONOMIC VALUE OF S^^AKES 



Many of the common snakes are largely-beneficial p.nd should" be pro- 

 tected. Such snakes are not poisonous and' although they may bite or at- 

 tempt to when captured, their bite is usually no more than a scratch and 

 is nonvenombus. Snakes devour large numbers of insects and mice, m.any 

 of Y/hich are injurious to garden crops and stored foodstuffs. 



One of the most abundant snakes in many parts of the United States is 

 the' common garter, or ribbon, sn-xke ( Thnmnophis ) . -The natural food of these 

 snakes consists of salnjnanders, small frogs, earthworms, insects, spiders. 



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