10 BULLETIN 1395, U. S. DEPARTMENT OF AGRICULTURE 



and selling it at tlie rate of 3 cents a pound, Mexican money. At 

 the time of the writer's visit in July thousands of bats were hanging 

 from the roof and several inches of excrement covered the floor, 

 giving on" an excessively strong odor of ammonia. The owner 

 stated that the bats migrate when the weather becomes cold in fall 

 and return in spring. Soon after they return they have their young. 

 At another place in the same town a man built a small detached 

 room in the yard back of his house for the purpose of smoking bacon 

 and other meat, but before he began to use it bats of this species 

 took possession in such numbers and produced so much guano that 

 he abandoned his original purpose and was making a good return 

 on his investment through the sale of guano. The writer heard also 

 of bat guano being taken from a cave on the southern slope of Mount 

 Popocatepetl. 



THE FLORIDA FREE-TAILED BAT 



The following extract from a letter from Hiram Byrd, State 

 Health Officer of Florida, to L. O. Howard, Chief of the Bureau of 

 Entomology, under date of June 26, 1912, relative to bats taking up 

 their abode in an uncompleted opera house begun in 1895, at Tavares. 

 Fla., undoubtedly refers to the Florida free-tailed bat, Tadarida 

 cynocephala, and if so shows that this species has the same colonial 

 habits as the one found in Texas: 



The doors and windows of the lower floor of this opera house were securely 

 fastened up to keep intruders out. but the upper windows were only closed by 

 loose boards, which soon dropped out, making it easily accessible to bats. 

 They took advantage of it, and in the course of a few years were there in 

 countless thousands. I know of no way of estimating the number. . . . The 

 only time I was ever there at the right hour was on a trip to Eustis. The 

 train stopped at Tavares one-half hour before sunset and remained there 

 something like 45 minutes. I took advantage of the occasion to see the bats 

 emerge from the building. I had only been watching a few minutes when 

 they began, first a single one. then two or three together, and as if the rustle 

 started them, then they began seriously flying out of the window with in- 

 credible swiftness. There must have been at least half a hundred a second. 

 I watched this stream of bats pouring out for half an hour or so. and was 

 told by some of the residents of Tavares that it would continue until something 

 like half an hour after dark, making probably two hours altogether. 



About two years after the opera house had been cleaned out and 

 converted into a packing house. Doctor Byrd made inquiries of 

 citizens in the vicinity of Tavares and Eustis, Fla., as to whether 

 they had experienced any appreciable difference in the number of 

 mosquitoes since the time the bat roost in the building was at its 

 height, and as a result of these inquiries stated that he was convinced 

 that if there was any difference it was not noticeable. 



MALARIAL CONTROL BY BATS 



During many years of study of the mammals of Mexico, the 

 writer lived a large part of the time in places where Mexican free- 

 tailed bats were extremely abundant. Their presence in no case 

 appeared to have the slightest influence on the prevalence of ma- 

 laria. In many Mexican villages and ranches, where nearly every 

 inhabitant was infected with malaria and where malarial mosquitoes 



