132 ECONOMIC MAMMALOGY 



Many of the Rodentia include insects in their diet, 30 some species to 

 a marked degree. Along the foothills in Colorado the striped ground 

 squirrel is said to "feed upon grasshoppers and other injurious insects, 

 almost to the exclusion of all other food." 31 Of 46 stomachs, 13 were 

 nearly or quite full of insects and 15 contained none. 32 Of 22 Iowa 

 stomachs, 46 per cent of the contents was insects, almost exclusively 

 injurious species, 33 while in 15 South Dakota stomachs a larger per- 

 centage of the insect contents consisted of harmless or useful species. 34 

 Of the contents of Franklin and Richardson ground squirrel stomachs, 

 50 per cent consisted of insects, according to Bailey's report of 1892, 

 but later reports do not seem so favorable, possibly due to different 

 conditions. 35 Of 35 stomachs of the chestnut-tailed squirrel of Utah 

 (Callospernwphilus castanurus) , 25 contained grasshoppers, beetles, 

 flies and larvae. 36 "Arboreal squirrels sometimes feed freely on scale 

 insects and other tree pests." 37 Gray squirrels are reported as having 

 destroyed oak apple galls. 38 Red squirrels are known to eat many in- 

 sects, 39 as probably all the other species do. 



Some of the wild mice are very much more highly insectivorous 

 than is generally supposed. In Michigan, of 4519 open cocoons of the 

 larch sawfly, more than 60 per cent had been opened by mice and only 

 a very small percentage had been parasitized by insect enemies or 

 attacked by fungi. 40 Much of the food of grasshopper mice consists 

 of soft-bodied insects such as grasshoppers and crickets, and the name 

 "scorpion mice" is sometimes applied to them because of their fondness 

 for scorpions. 41 The food of the harvest mice resembles that of the 



^Klugh, Journ. Mammalogy, viu, 1-32, 1927. Howell, N. Amer. Fauna, No. 45, 

 p. 62, 1921. 



31 Burnett, Office Colorado State Entom. Circular No. 18, p. 6, 1916. See also Bailey, 

 N. Amer. Fauna, No. 49, p. 52, 1926; U. S. Div. Orn. and Mam. Bull. No. 4, 1893. 

 Hisaw and Emery, Journ. Mammalogy, viu, 41-44, 1927. 



32 Burnett, Office Colorado State Entom. Circular No. 14, 1914. 



33 Gillette, Iowa Agric. Exper. Sta. Bull. No. 6, 1888. 



34 Aldrich, South Dakota Agric. Exper. Sta. Bull. No. 30, 1892. 



35 Bailey, Ann. Kept. U. S. Dept. Agric. for 1892, pp. 185-192; N. Amer. Fauna, 

 No. 49, pp. 55, 59, 1926. 



36 Merriam, N. Amer. Fauna, No. 4, p. 19, 1890. 



37 McAtee, Ann. Rept. Smithsonian Inst. for 1925, p. 416. 



38 Davis, Oak apple galls destroyed by gray squirrels, Bull. Brooklyn Entom. Soc., 

 xix, 91-93, 1924. Journ. Mammalogy, v, 274, 1924. 



^Hatt, Roosevelt Wild Life Bull., n, 109-110, 1929. See also Insects as the food of 

 squirrels, Canadian Entomologist, xxxix, No. I, p. 16, 1907. 



40 Graham, The larch sawfly as an indicator of mouse abundance, Journ. Mam- 

 malogy, x, 189-196, 1929. 



41 Gary, N. Amer. Fauna, No. 33, 1911. Merriam, ibid., No. 3, 1890. Bailey, ibid., 

 No. 49, p. 81, 1926; Farmers' Bull., No. 335, p. 13, 1908; Animal life of Carlsbad 

 Cavern, 1928. Burnett, Office^ Colo. State Entom. Circular No. 25, p. 7, 1918. Bailey 

 and Sperry, U. S. Dept. Agric. Technical Bull. No. 145, 1929. 



