198 ECONOMIC MAMMALOGY 



As the activity of bats during flight demands a great deal of food 

 and there is not much nourishment in most flying insects, the quantities 

 of insects consumed by a large colony of bats is enormous. The Pipi- 

 strelle bats (Pipistrellus subflavus subflavus) are found with stomachs 

 "distended with small dipterus and coleopterus remains." 5 The stomachs 

 of little canyon bats (Pipistrellus hesperus) taken early in the evening, 

 after twenty minutes of flight, were invariably found to be gorged with 

 freshly eaten insects, 6 and probably they usually take several such meals 

 each night when insects are abundant. It has been estimated that at 

 such times each free-tailed bat (Tadarida cyanocephala) will nightly 

 eat enough insects to equal its own weight or more. 7 



Two little brown bats (Myotis lucifugus) in captivity preferred noc- 

 tuid moths and took from eight to ten at a meal, w r ith meals half an 

 hour apart, handling moths as large as the red underwing. 8 Pellets of 

 the California leaf-nosed bat (Macro tits calif ornicus} contained two 

 species of grasshoppers, four of moths, with harvest flies, beetles and 

 the gorged viscera of an insect, probably a grasshopper. 9 Pellets of Say's 

 bat (Myotis subulatus) contained remains of numerous Diptera, spiders, 

 a scarabaeoid beetle and a cuckoo-fly. 10 Pellets of the Pacific pallid bat 

 (Antrozous pallidus pacificus) contained remains of Jerusalem crickets, 

 scorpions, a beetle and fragments of other insects, including grasshop- 

 pers. 11 It is said that the destruction of bats in Germany in 1800 caused 

 an increase of processional moths which ruined the trees of a large 

 region. 12 



Bats sometimes, in the daytime, hang from the walls of caverns and 

 similar places in prodigious numbers, emerging in the evening in swarms 

 and scattering over the surrounding country in search of insects. The 

 accumulation of guano in the roosting caverns in the course of centuries 

 forms deposits of commercial importance. It was estimated that on one 

 May evening 100,000 bats emerged from the great Carlsbad Cavern 



5 Hamilton, Journ. Mammalogy, xi, 307, 1930. 



6 Bailey, Biological survey of Texas, N. Amer. Fauna, No. 25, pp. 210-211, 1905; 

 Harmful and beneficial mammals of the arid interior, with special reference to 

 Carson and Humboldt Valleys, Nevada, Farmers' Bull., No. 335, p. 31, 1908. 



7 Nelson, U. S. Dept. Agric. Bull. No. 1395, 1926. 



8 Pittman, Notes on the feeding habits of the little brown bat, Journ. Mam- 

 malogy, v, 231-233, 1924. 



9 Huey, Food of the California leaf-nosed bat, Journ. Mammalogy, vi, 196-197, 

 1925- 



10 Seton, A roving band of Say's bats, Journ. Mammalogy, m, 52, 1922. 



11 Hatt, Food habits of the Pacific pallid bat, Journ. Mammalogy, iv, 260-261, 

 1923. See also Grinnell (Hilda Wood), A synopsis of the bats of California, Univ. 

 California Pub. Zool, xvii, 235-255, 1918. Nelson, Nat. Geog. Mag., xxxm, 493, 

 1918. 



12 Schmeil, Textbook of Zoology, p. 66. 



