236 ANNUAL REPORTS OP DEPARTMENT OF AGRICULTURE. 



INSECTS AFFECTING THE HEALTH OF DOMESTIC ANIMALS. 



Work on insects in relation to packing houses and abattoirs has 

 been continued throughout the year. These investigations are carried 

 on cooperatively with the Bureau of Animal Industry and the work 

 was devoted especially to the problem in connection with the estab- 

 lishments operated under the meat-inspection service. Attention 

 has been given to the improvement of construction and arrangement 

 of equipment about packing establishments in order to prevent per- 

 manently the formation of suitable breeding places for flies. Inves- 

 tigations of methods of destroying larvae in various breeding media 

 which can not be readily prevented from becoming infested have 

 been continued. Further progress has been made in the destruction 

 of adult insects by means of traps and poisoned baits. 



In connection with this investigation the fact developed that many 

 flies assembled in the vicinity of slaughter houses, even though no 

 breeding places were present on the premises. This suggested the 

 need of studies on the flight of the several species of flies that are of 

 more or less importance. Preliminary experiments indicate that both 

 meat flies and the house species fly considerably farther than has been 

 supposed. 



The extensive use of screen-wire cloth for the protection of food 

 throughout the country, and the lack of knowledge concerning its 

 durability and its efficiency in protecting man, led to a series of tests 

 to determine the fineness of mesh necessary to exclude various insects, 

 and other tests to determine the relative durability of various kinds 

 of screen in different climes. 



Work on the screw-worm fly has been continued. The proper de- 

 struction of carcasses of animals is the most important step in control, 

 and methods of carcass disposal have been given further attention. 

 The relationship between climatic conditions and severe outbreaks 

 of this insect is very intimate and is receiving attention. The more 

 important findings obtained in the course of the work on this project 

 ha^'e been prepared for publication as Farmers' Bulletin 857. 



The work on horseflies has been expanded by placing an agent in 

 the field in Nevada and California to conduct investigations in coop- 

 eration with the Nevada Experiment Station. Although this work 

 was begun rather late in the season, satisfactory progress has been 

 made looking toward the determination of the breeding places and 

 habits of the several species that are of considerable importance to 

 the live-stock industry there. The work in southwestern Texas on 

 this project has progressed satisfactorily, but the habits of insects 

 of this group render their control very difficult. 



Work on the biology of the common ox warble of the United States 

 {Hypoderma Uneatum) has been continued and some findings have 

 been made which doubtless can be utilized in control work. Further 

 attention has been given to the question of the distribution, abund- 

 ance, and injuriousness of the two species of warbles occurring in 

 this country. The experiments in controlling the ox warble by ex- 

 tracting the grubs from the backs of cattle on individual farms have 

 been continued. 



