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hygienic value of the roost would not cause it to be built, but 

 that the dollars and cents would, and the hygienic value would 

 follow. He had constructed a roost at the experimental farm 

 of the Bureau of Plant Industry of the U. S. Department of 

 Agriculture some six miles south of San Antonio, and since that 

 time has published a number of newspaper articles, has secured 

 the endorsement of the San Antonio Academy of Medicine and 

 the Bexar County Medical Society, and the idea of bat roosts in 

 malarious localities has thus spread far and wide over the 

 country and is naturally attractive on account of its simplicity 

 and on account of the possible commercial gain. 



I have not looked into the question of commercial gain, but 

 from: the standpoint of mosquito destruction and consequent 

 relief from malaria, I have felt impelled to make certain investi- 

 gations, which, however, have not gone so far as to induce 

 actual experimentation by the erection of an experimental bat 

 roost in any part of the country. 



Rather glowing 1 claims are made in San Antonio concerning 

 the disappearance of malaria in the vicinity of the bat roosts 

 erected, and these are fortified by the sworn statements of cer- 

 tain Mexican families residing in the neighborhood before and 

 after the roosts were erected. 



During 191 3 and 1914 I directed Mr. F. C. Bishopp, in charge 

 of the field laboratory of the Bureau of Entomology at Dallas, 

 T'exas, to visit San Antonio and investigate the Campbell bat 

 roost and the relation of bats to mosquitoes and the prevalence 

 of malaria. Mr. Bishopp went to San Antonio on several 

 occasions and made observations concerning bats and mosquitoes, 

 not only there but at Uvalde and along the foothills north of 

 that town where myriads of the common bat of that region live 

 in the numerous limestone caves. He reported that Doctor 

 Campbell's first bat roost was built in 1909 on the Experimental 

 Farm of the Bureau of Plant Industry of the Department of 

 Agriculture, but the bats were not induced to live in this roost; 

 at the time of Mr. Bishopp' s visit it was not occupied by them. 

 In 1910 another bat roost, with slight modifications, was built 

 at the head of Mitchell Lake, some ten miles from San Antonio. 



