BUREAU OF ENTOMOLOGY. 223 



for repelling the flies, and others for the destruction of the bots, are 

 being tested. In the course of the work it has been found that a 

 fungous disease appears to destroy a considerable percentage of the 

 bots in nature. This disease is being studied. The relationship be- 

 tween bots and the disease of horses known as infectious anemia is 

 receiving consideration. 



Poultry pests. — Extensive investigations of poultry pests, par- 

 ticularly the common red mite and various species of chicken lice, 

 have been carried on with the result that very satisfactory control 

 measures have been developed. It has been determined that sodium 

 fluorid is effective against the lice. A single application of a very 

 small quantity of this material has been found to destroy completely 

 all stages and all species of lice on a fowl. Entire flocks have been 

 cleared up in this manner. These remain free of lice when ordinary 

 precautions are taken against reinfestation by intimate contact with 

 infested fowls. In these investigations the life histories of several 

 economic species of lice have been worked out for the first time. The 

 biology of the chicken mite (Dermanyssus gallinae) has been care- 

 fully followed for the first time. It has been determined that the 

 mite depends exclusively upon the fowl for its food and will not 

 develop in any stage on filth or excrement. In tests of a large series 

 of insecticides it has been found that a few thorough applications of 

 crude petroleum to the interior of poultry houses will completely 

 destroy the mites. The painting of the roosts and nests with a pro- 

 prietary compound containing carbolic acid also gave satisfactory 

 results. 



CEREAL AND FORAGE INSECT INVESTIGATIONS. 



To January last the work on cereal and forage-crop insects was 

 conducted under the direction of Prof. F. M. Webster, who died sud- 

 denly in that month; since his death the work has been conducted 

 under the supervision of the chief of the bureau. 



Alfalfa weevil. — The alfalfa weevil has spread rapidly during 

 the year, and the territory inhabited by it now extends north to 

 Standrod, Malta, Holbrook, Blackfoot, and Montpelier, Idaho; east 

 to Duchesne, Utah, and south to Richfield, Utah. Valuable informa- 

 tion as to the means and extent of its travel, and particularly as to 

 what farm products can be shipped with safety from infested terri- 

 tory, has been collected and given to various quarantine officials, with 

 the result that farm products, except alfalfa hay and commodities 

 which have been packed and handled with alfalfa hay, are now gener- 

 ally admitted to be harmless, and several important markets have 

 been opened to infested districts. 



The cost of spra}dng fields has been reduced from an average of $1 

 to 85 cents per acre, and the conditions which insure success have been 

 largely determined. Rotation pasturing has proved a perfect pro- 

 tection against the weevil and a practical method for certain kinds of 

 farms, and it is believed that a study of the farm-management prob- 

 lems of the region inhabited by the weevil will show that most of the 

 farms can profitably use this method. Continuous pasturing of hogs 

 has proved unexpectedly useful in saving the first crop and destroy- 



