254 ANNUAL EEPORTS OF DEPARTMENT OF AGRICULTURE. 



the animals has been completed on about 1,000,000 acres at an average 

 cost of from 5 to 10 cents an acre, resulting in the destruction of about 

 90 per cent of the animals. In addition 289,000 acres on which the 

 first poisoning had already been done were given a second treatment, 

 resulting in the practical extermination of the pests. As many as 

 300 dead prairie-dogs have been counted in an alfalfa field within 

 24 hours as a result of distributing grain poisoned with only one 

 ounce of strychnin. The importance of this work is made evident by 

 an estimate of the Forest Service that the range for live stock im- 

 proves 50 per cent after the prairie-dogs have been destroyed. 



The success of this work on public lands has induced extensive 

 cooperation by private owners. Farmers and stockmen have been 

 aided by demonstrations and have been assisted in organizing, direct- 

 ing, and supervising comprehensive campaigns. As a result a large 

 saving has been effected in growing crops and good yields have been 

 secured on large areas where in many cases the prairie-dog infestation 

 had previously rendered the production of crops an almost hopeless 

 undertaking. Arrangements have been made to increase this work 

 through cooperation with the extension services of several States. 



POCKET GOPHERS. 



The elimination of pocket gophers from the Ochoco National 

 Forest of Oregon was continued cluring the fall, and 95 per cent of 

 the animals were destroyed from about 13,000 acres which had been 

 heavily infested. Extensive demonstrations of methods of poisoning 

 were held among the farmers in California, Washington, Oregon, 

 and Idaho, resulting in the elimination of these destructive pests 

 over considerable areas of orchard and other farm lands. 



NATIVE MICE AND RATS. 



Pine mice, meadow mice, and deer mice have wrought serious 

 havoc in orchards, gardens, and truck and potato farms, as well as 

 in melon-producing districts throughout extensive areas, especially 

 in the Eastern States. Investigations have been conducted and 

 demonstrations of effective methods for the eradication of these pests 

 have been given in Virginia, West Virginia, Pennsylvania, Maryland, 

 Ohio, Indiana, and Iowa, and advice for protection against them has 

 been given on request in many other States. In one county in Vir- 

 ginia the horticultural commissioner estimated a loss of $100,000 to 

 orchardists from apple trees killed by pine mice during the year. 



Investigation of damage to forest nursery stock b}^ wood rats has 

 been conducted on the planting areas of the Converse Experiment 

 Station of the Forest Service in California. Many facts of im- 

 portance relating to their habits and depredations have been deter- 

 mined and advances made in the methods for their control. 



HOUSE RATS AND MICE. 



The initial steps have been taken to launch a nation-wide campaign 

 for the more adequate control of house rats and mice, notorious de- 

 stroyers of field crops, stored products, and poultry. Many data rela- 

 tive to damage by them have been assembled, and present conditions 

 in many localities were ascertained by direct inspection. Efforts 



