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infection of cattle with Piroplasma bigeminum can only be efEected 

 in nature by the offspring of an infected tick. The parent tick is 

 not therefore a direct carrier as an individual, but as the infection 

 passes through the eggs its chances of reaching a susceptible animal 

 are enormously multiplied. Dermacentor venustus, which is the 

 carrier of Rocky Mountain spotted fever, is next dealt with. In the 

 Bitter Root Valley of Montana, where the virulent type exists, the 

 mortaUty from the disease is from 70 to 80 per cent., while in other 

 neighbouring States a less malignant type occurs, with a mortaUty 

 record of only 5 per cent. D. venustus has never been reported from 

 Arizona, although known to exist in every adjoining State. In 

 California it has been found only in the extreme north-east corner, 

 and in New Mexico only in the north central portion. In Arizona 

 species of Anopheles which carry malaria are unknown to the author, 

 and the cUmate is too arid for Stegomyia to be hkely to breed there. 

 Dengue fever has been proved to be carried by mosquitos of the genus 

 Culex, and in the irrigated valleys of Arizona, road-sides flooded 

 with irrigating water and drinking holes for stock provide ideal breed- 

 inglplaces for these mosquitos. 



Pediculus vestimenti is beheved to be the only carrier of typhus 

 fever, and therefore the prevention of this disease should become a 

 simple matter. Clinocoris {Cimex) lectularius is the known trans- 

 mitter of leishmaniasis and cases of transmission of anthrax and 

 leprosy by bed-bugs are recorded. The author has been unable to 

 find any record of the existence of the bed-bug in the more densely 

 populated Salt River Valley of Arizona, but at a certain locahty in 

 the central portion of the State, at an elevation of about 2,000 feet, 

 this pest was on one occasion forced upon his attention. In south- 

 west Arizona Triatoma (Conorhinus) sanguisuga, variously known 

 as the " blood-sucking cone-nose," the " bellows bug," the " Arizona 

 tiger," or the " Arizona bed-bug," is a troublesome household pest. 

 The bite of this bug frequently produces red blotches on the body, 

 and while the injection of a specific poison by the insect is admittedly 

 probable, recent discoveries lead to the suspicion that various patho- 

 genic organisms are not infrequently carried by it. A South American 

 disease, known as " Barbiero fever," has recently been proved to be 

 carried by species of Triatoma. The connection of bubonic plague 

 with rat fleas and Florida sore eye with Hippelates, and the possible 

 connection of pellagra with Simulium, and infantile paralysis and 

 surra with Stomoxys calcitrans, are briefly indicated. 



Summarising the more important observations and discoveries 

 in connection with house-fly investigations, the author says that in 

 one case the average number of bacteria on the bodies of 414 house- 

 flies was found to be IJ million. Those collected in swill-barrels 

 averaged about 4 milhon bacteria per fly, while specimens in more 

 cleanly surroundings averaged only about one-tenth as many. House- 

 flies will ingest tubercular sputum and excrete tubercle bacilli, the 

 virulence of which may last 15 days. 



Omitting diseases beheved to be insect-borne, but concerning which 

 there is still some doubt, the total estimated loss to the United 

 States from disease-carrying insects is 357 million dollars annually. 



(C68) a2 



