Some persons uninformed as to the need for rodent control and the methods followed by the Biological Survey in carrying on the work have stated that control by use of poison and C.C.C. workers endangers the existence of other forms of wildlife. This, however, is not the case. The Biological Survey has studied rodent-control methods for more than twenty years and in this period it has developed the most scientific and selective poisons possible. Scientific investigations conducted by the Bureau are bringing increasing knowledge of the habits of economically injurious species and of their physiological reaction to various baits. This has made it possible to use more and more specific control methods and so to select, prepare, and expose poison baits as not seriously to endanger animals other than those for which the baits are intended. When these scientific methods are carried out under direct supervision of trained personnel, the total number of beneficial species destroyed is negligible. The Biological Survey is a conservation organization and will undertake no work that will be detrimental to any species of animal not interfering too greatly with the interests of man. Those conversant with actual conditions in the range States realize that if agriculture is to survive, the control of injurious rodents is as essential as is control of the corn borer, the chinch bug, the boll weevil, the grasshopper, the coddling moth, and numerous other agricultural pests. The Survey insists that in conducting work of this sort, the most careful supervision by trained technicians must be given. All cooperating agencies recognize the necessity for such supervision, and as a result a most worth-while program has been carried on during the past three fiscal years. The Biological Survey has entered into written cooperative understandings with the various governmental agencies under which rodent-control activities have been conducted. These agreements place the responsibility for technically supervising all rodent-control activities in the hands of the Bureau, leaving the cooperating agencies responsible for administration. Control Work Illustrated The illustrations on the following pages tell better than would volumes of written words, the story of rodent damage and of cooperative work to reduce this damage. PRAIRIE DOGS Four years experimental study in northern Arizona showed that prairie dogs destroy 60 percent of the wheat grass, 99 percent of the dropseed, and 83 percent of the grama grass, or 80 percent of the total potential annual production of forage. The possible destruction of four-fifths of the forage, or even a far smaller proportion, is serious enough at any time, but in periods of drought it is likely to be calamitous. The following pictures show typical prairie dog infestation. [Illustration] Prairie dog mounds on abandoned Indian farm, Southern Navajo Reservation, Arizona. [Illustration]