CHIROPTERA 199 



in southern New Mexico. When this cavern was discovered years ago, 

 guano filled some of the largest rooms to a depth of 100 feet, coming up 

 nearly to the openings, and sloping away for hundreds of yards over 

 the cave floor, representing a great many centuries of deposition. It is 

 estimated that 100,000 tons of it have been removed and marketed at 

 from $20 to $75 per ton, or a total of much more than $2,ooo,ooo. 13 



The food of British insectivorous bats consists chiefly of injurious 

 moths and beetles. Leisler's bat (Nyctalus leisleri) one hour after sun- 

 set was found crammed full of insects. The water bat (Myotis dauben- 

 toni) feeds largely on caddis-flies. A mouse-eared bat ate 1 500 house- 

 flies in one night, and another ate 80 grasshoppers in one night. 14 The 

 oriental bats of the genus Megadermus feed largely on small birds and 

 even on other bats. 15 



One group of bats (Noctilio), found in Porto Rico, Trinidad, and 

 Virgin Islands, has formed the habit of eating fishes. There have been 

 many observations of their scooping the surface of the water, appar- 

 ently for food, and there is some direct evidence of their eating fish. 

 A number of stomachs examined contained nothing but fish, though 

 many contained insects, such as beetles, ants, mole-crickets, with some 

 spiders. 16 They probably do little or no harm and much good. 



A small family of South American bats, which reach much greater 

 size than the North American bats, sometimes with a wing expanse up 

 to 28 inches, have acquired the name vampires from their habits of 

 sucking the blood of other mammals, including human beings. Two 

 species have been said to subsist entirely upon a diet of blood. 



The flying foxes, or fruit bats (Pteropodidae), ranging from Africa 

 to Japan, Australia and Polynesia, reaching a large size and feeding 

 chiefly upon fruit, are abundant in some places and very destructive 

 to tree fruits. One Malay species is said to have a body eighteen inches 

 long, with a wing expanse of five feet from tip to tip. The United States 

 government is constantly on guard to prevent their introduction into 

 the United States. 17 



"Bailey, Bats of the Carlsbad Cavern, Natl. Geog. Mag., XLVIII, 321-330, 1925; 

 Animal Life of the Carlsbad Cavern, pp. 108-129, 1928. Nelson, U. S. Dept. Agric. 

 Bull. No. 1395, 1926. 



14 Poulton, British insectivorous bats and their prey, Proc. Zool. Soc. London for 

 1929, pp. 277-303- 



15 Poulton, Proc. Zool. Soc. London for 1929, p. 300. 



18 Benedict, Notes on the feeding habits of Noctilio, Journ. Mammalogy, ix, 

 58-59, 1928. Goodwin, Observations on Noctilio, Journ. Mammalogy, ix, 104-112, 1928. 



17 Palmer, The danger of introducing noxious animals and birds, Yearbook U. S. 

 Dept. Agric. for 1898, pp. 96-98. 



