BUREAU OF ENTOMOLOGY. 237 



Much valuable information has been obtained on the life history 

 and habits of the three species of horse bots that occur in the United 

 States, and the data, with suggestions for control, have been prepared 

 for publication. A nose protector for horses, which appears suitable 

 for preventing infestation by the bots, has been developed in the 

 course of the work. The nose fly, which has been given special at- 

 tention, is continuing to spread southward and eastward. Its recent 

 distribution has been mapped. 



Further work on the common chicken mite and various species of 

 lice on poultry has been carried on with the view of making the 

 results more uniformly successful and reducing cost of treatment. 

 In addition to studies of the poultry parasites that are most fre- 

 quently the subject of complaint, work has been done on the deplum- 

 ing mite and certain other mites that cause more or less local trouble. 

 What appear to be very satisfactory methods of control have been 

 found. 



The use of sodium fluorid proved so successful against chicken lice 

 that experiments were conducted to determine its effect on lice of 

 horses, cattle, and other domestic animals. The use of this material, 

 either in liquid or dry form, was found very satisfactory, but its 

 greatest advantage will accrue from the fact that it can be used in 

 dust form during the winter months, when the dipping of live stock is 

 objectionable. 



CEREAL AND FORAGE INSECT INVESTIGATIONS. 



In the last annual report the death of Prof. F. M. Webster, who 

 organized this section of the bureau's work, was announced. In 

 March, 1917, Mr. W. R. Walton was placed in charge. 



Grasshoppers. — Two severe outbreaks of grasshoppers, involving 

 many hundred thousands of acres, occurred during the early summer 

 of 1917 in California and western Montana. In the latter State much 

 of the territory involved was Indian land, on the Flathead Reserva- 

 tion, and for this reason the Bureau of Indian Affairs appropriated 

 the sum of $1,000 for the purpose of providing material and labor 

 in poisoning the grasshoppers. Two expert entomologists from this 

 bureau w^ere detailed to work in an advisory capacity in cooperation 

 with the States Relations Service and the State authorities. Good 

 progress has been reported in eliminating this outbreak. In Cali- 

 fornia the outbreak was more general in character, involving to a 

 greater or lesser extent the following counties: Humboldt, Glenn, 

 Butte, Colusa, Yuba, Nevada, Contra Costa, Merced, Tulare, San 

 Diego, Imperial, and- Stanislaus. Two experts, one of them engaged 

 expressly for this purpose, acted in cooperation with the State exten- 

 sion workers in combating the outbreak. Investigations were con- 

 ducted with the view of reducing the cost of poisoned baits and 

 utilizing such insecticides as are most available during the present 

 emergency. 



Hessian fly. — The great general outbreak of the Hessian fly that 

 occurred throughout the United States during the years 1914-1916 

 has abated very perceptibly, excepting in eastern Kansas, where seri- 

 ous infestation of the 1917 crop threatens severe injury to the winter- 



