10 SPERMOPHILES OF THE MISSISSIPPI VALLEY. 



also the Great Plains as far west as the foothills of the Bocky Moun- 

 tains. In a north and south direction it embraces the vast area stretch- 

 ing from the Mexican boundary and the Gulf of Mexico north to the 

 plains of the Saskatchewan Biver. It comprises the largest and by far 

 the most important continuous stretch of agricultural land on the con- 

 tinent, and the greater part of it is now under high cultivation. Five 

 very distinct species of spermophiles inhabit this region, four of which 

 are restricted to it, namely: Bichardson's Spermophile (Spermophilus 

 richardsoni), Franklin's Spermophile (Spermophilus franJclini), the 

 Striped Spermophile (Spermophilus tridecemlineatus), and Kennicott's 

 Spermophile (Spermophilus spilosoma obsoletus) ) the fifth, the Mexican 

 Spermophile (Spermophilus mexicanus), ranges southward over the 

 table-land of Mexico as far as the Valley of Mexico. Only two species 

 (S. franklini and S. tridecemlineatus) range east of the Mississippi 

 Eiver, and these find their extreme eastern limits respectively in west- 

 ern Indiana and eastern Michigan. 



On account of the immense damage done to crops these animals have 

 been the subject of investigation at some of the agricultural colleges and 

 experiment stations in the West, and several bulletins have been issued 

 containing notes on their food habits or giving directions for their 

 destruction. 



In 1878 Prof. E. W. Hilgard, of the University of California, published 

 a bulletin on the destruction of ground squirrels by the use of bisul- 

 phide of carbon.* This method has proved by far the most successful 

 of any thus far put in practice, and has been largely adopted with 

 gratifying success. (See pp*. 29-30.) 



Mr. E. J. Wickson in his work on California Fruits devotes a para- 

 graph to methods of destroying ground squirrels in orchards.f He rec- 

 ommends three means of extermination : (1) Poisoned wheat; (2) bisul- 

 phide of carbon, and (3) i smokers.' The latter term includes the various 

 devices for burning sulphur or damp straw and forcing the fumes into 

 the burrows, thereby suffocating the inmates. 



In August, 1889, Prof. C. P. Gillette published the results of an exam- 

 ination of the stomachs of twenty-two specimens of the Striped Sper- 

 mophile (Spermophilus tridecemlineatus) in a paper entitled i Food Hab- 

 its of the Striped Prairie Squirrel.'! He showed that this species 

 is not an unmixed evil, for besides large quantities of grain, it eats 

 numbers of grasshoppers, wireworms, and other noxious insects. He 

 concludes that a large proportion of its food is made up of insects, 

 which seem to consist almost exclusively of injurious species, chiefly 

 cutworms, webworms, and grasshoppers, and adds: "The squirrels 

 would be a most valuable adjunct to any cornfield after planting if 

 some method could be devised to prevent them from taking the corn." 



* Bulletin of the University of California, No. 32, April, 1878. 



tE. J. Wickson: The California Fruits and How to Grow Them. San Francisco, 

 1889, p. 554. 

 t Bulletin No. 6, Iowa Agricultural Experiment Station, August, 1889, pp. 240-244. 



