CHIROPTERA 197 



including many kinds of injurious moths and beetles not often taken 

 by insectivorous birds of diurnal habit. 1 In the dusk of early evening 

 and on moonlight nights they may be seen flying about seeking and 

 catching their prey, their erratic flight being the result of the search 

 for and pursuit of insects. 



Though they certainly perform a great service to mankind in keep- 

 ing many troublesome and harmful insects within bounds, their value 

 as destroyers of mosquitoes may not be so great as many people have 

 supposed. Several years ago much newspaper publicity was given a book 

 based upon the theory that the encouragement of bats by the erection 

 of "baj: towers" would not only rid the adjacent region of mosquitoes, 

 but would also provide a revenue from the guano they would deposit, 2 

 this being simply the waste from the insects eaten by the bats. The 

 experiment described was very interesting, but in most regions the 

 accumulation of guano would be too slow to yield much revenue, and 

 a study of the flight habits of bats, together with an examination of 

 their pellets and guano, do not support the belief that they are very 

 large consumers of mosquitoes. 3 This is not because of any aversion 

 to mosquitoes as a diet, but probably because the usual flight of the 

 bats is too high to catch the swarms of mosquitoes, especially the ma- 

 laria mosquitoes, which fly not far above the ground. Consequently 

 the supposed efficacy of bats in preventing mosquitoes from spreading 

 malaria is not well founded. Localities where bats are very numerous 

 are often afflicted with malaria and clouds of mosquitoes. However, 

 bats do sometimes fly near the ground, even capturing beetles and other 

 insects on the ground, and doubtless do take some mosquitoes. Fargo 

 attributed the absence of mosquitoes from Bird Key, Florida, to the 

 presence of bats, mosquitoes being numerous on neighboring keys, 

 where there were no bats, 4 a rather strong case based upon circumstan- 

 tial evidence. In this connection we might say that the popular notion 

 that bats harbor and distribute bedbugs seems to be without foundation. 



1 Grinnell, Bats as desirable citizens, California Fish and Game Comm. Teachers' 

 Bull., No. 6, 1916. 



2 Campbell, Bats, mosquitoes and dollars, 1925. 



3 Storer, Bats, bat towers and mosquitoes, Journ. Mammalogy, vn, 85-90, 136-138, 

 1926; Science, LXIII, 337-338, 1926. Goldman, Journ. Mammalogy, vii, 136-138, 1926. 

 McAtee, The role of vertebrates in the control of insect pests, Ann. Rept. Smith- 

 sonian Inst. for 1925, p. 416. Nelson, Bats in relation to the production of guano 

 and the destruction of mosquitoes, U. S. Dept. Agric. Bull. No. 1395, 1926. Howard, 

 Mosquitoes and bats, U. S. Public Health Reports, xxxv, pp. 1789-1795, 1920. Hall, 

 Economic value of the Mexican free-tailed bat, California Fish and Game, xn, 136- 

 137, 1926. 



* Fargo, Bats of Indian Key, Tampa Bay, Florida, Journ. Mammalogy, x, 203-205, 

 1929. 



