BUREAU OF ENTOMOLOGY. 219 



larvas in stable manure, another substance, hellebore, has certain 

 advantages. If excessive amounts of borax are applied there is 

 likely to be injurj^ to crops when the manure is used as a fertilizer; 

 but hellebore, being volatile, does not have any injurious effect 

 whatever on the manure. Important results were also obtained in 

 testing other means of controlling the house fly, particularly in the 

 use of the so-called maggot trap, which furnishes a very economical 

 means of removmg the larvee from manure without the addition of 

 any chemicals. In fact, the use of the maggot trap will enable the 

 farmers to obtain more fertilizing value from the manure than is the 

 case under the usual methods of management. 



The work on the spotted-fever tick m Montana was continued in 

 cooperation with the Montana Board of Entomology and the United 

 States Public Health Service. The operations consisted of systematic 

 dippmg of the animals which support the adult stage of the tick. The 

 work was well received by the people directly concerned and promises 

 to reduce very greatly the number of cases of spotted fever in the 

 Bitter Root Valley. 



The work on the possible transmission of pellagra by insects, 

 which had been under way for two years in cooperation with the 

 Thompson Pellagra Commission, was discontmued for the reason 

 that the findings indicated that there is only an extremely remote 

 possibility that insects may be concerned in the spread of the disease. 



A new line of work was instituted at the urgent request of the 

 Bureau of Animal Industry, namely, an investigation of house flies 

 and related insects in the estabhshments operating under the meat 

 inspection act. These meat-packing estabhshments present many 

 peculiar problems in the control of me house fly. An agent visited 

 several of the larger establishments in the country and was able to 

 supply information that enabled the Bureau of Animal Industry to 

 take immediate steps that had the effect of reducing greatly the 

 annoyance and danger from flies in the estabhshments operating 

 under Federal control. 



INVESTIGATIONS OF INSECTS AFFECTING THE HEALTH OF ANIMALS. 



The investigations of insects which affect the health of animals 

 dealt with the flies causing myiasis, with the so-called nose fly of the 

 North Central States, with the stable fly, horn fly, ox warbles, and 

 other species. The so-caUed screw-worm fly attacks living animals 

 throughout the southwestern part of the United States. In some 

 locations it is so abundant that it causes heavy mortahty among 

 young calves. Tlie investigations showed that this pest develops 

 very largely in carcasses, and experiments were conducted to deter- 

 mine the proper methods of preventing the breeding of the pests in 

 such situations. Extensive tests were also made of various sub- 

 stances which attract the adult fhes and which may possibly be 

 used in attracting the insects to traps or poisoned baits. 



It is found that the so-caUed wool maggot of sheep is a source of 

 considerable loss to producers in western Texas as well as in other 

 States, Apparently the attack on sheep is a recently acquired habit 

 of one of the species of blowfly. As the blowflies of other countries, 

 notably Australia, are very important in causmg losses to sheep raisers, 

 it is possible that the American species may eventuaUy develop into a 

 pest of prime importance. It therefore requires special investigation. 



