536 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



EPIDEMIC AMONG WIXX) DUCKS AT GREAT SALT LAKE. 



Followino: a lonjr dry season, which favored the rearing: of a hirge 

 number of wild ducks, but materially reduced the area of the feeding 

 ponds, resulting in great overcrowding, a severe epidemic broke out 

 about August 1, 1910, among the wild ducks about Great Salt Lake, 

 Utah. Dead ducks could be counted by thousands along the shores 

 and the disease raged unabated until late fall. Shooting clubs found 

 it necessary to declare a closed season. Some of the dead ducks were 

 forwarded to the Biological Survey and were turned over for ex- 

 amination to the Bureau of Animal Industry, by the experts of 

 which the disease was diagnosed as intestinal coccidiosis. 



Various plans of relieving the situation were tried : The irriga- 

 tion ditches were closed, thus providing the sloughs and ponds with 

 fresh water, and lime was sprinkled on the mud flats and duck trails. 

 Great improvement followed this treatment, and experiments proved 

 that ducks provided with abundant fresh water and clean food began 

 to recover immediately. These methods promised success, but later 

 it was proposed that the marshes be drained and exposed to the 

 sun's rays — a course which can not be recommended. That coccidia 

 are not always killed by exposure to the sun is shown by their sur- 

 vival on the sites of old chicken yards. An added disadvantage of 

 the plan is that draining and drying the marshes would have a bad 

 effect on the natural duck foods and upon the birds themselves. 



ALFALFA AVEEVIL. 



The recently imported alfalfa weevil threatens to add a very 

 injurious insect pest to the many existing in the United States. 

 Already seriously destructive in Utah, should the insect continue to 

 spread it is likely to endanger the alfalfa industry throughout the 

 Western States. The Biological Survey is cooperating with the 

 Bureau of Entomology in investigations to devise means of check- 

 ing the spread of the weevil. Preliminary work has already shown 

 that a number of birds feed on the insect, and it is hoped to spread 

 this information among the farmers and so secure their aid in 

 furthering measures for the protection and increase in numbers of 

 these particular species. 



GROUND SQUIRRETiS. 



During the year field investigations and experiments were con- 

 tinued to discover better methods of destroying ground squirrels in 

 the National Forests and elsewhere. In order to test the efficacy 

 and cheapness of the strychnine-starch solution recommended in Cir- 

 cular No. 36, several demonstrations on a rather extensive scale were 

 undertaken in California. The Kern County Land Co., of Cali- 

 fornia, under the supervision of the Biological Survey, successfully 

 treated 29,000 acres of alfalfa with poisoned grain for the purpose of 

 exterminating ground squirrels over the area. At the Jesus Maria 

 Rancho an assistant of the Biological Survey supervised the de- 

 struction of ground squirrels over about 25 square miles of range 

 lands and practically exterminated them at a cost of about 4 cents 

 an acre. In winter, experiments were carried on in the San Joaquin 



