Among the worst enemies of the prairie farmer in Western Canada are the various species of Citellus a type of burrowing rodent commonly referred to as the Ground Squirrel or the Gopher. These animals are most difficult to keep in check and they cause an immense amount of damage to cultivated crops. The annual loss to agriculture in the State of North Dakota, for example, has been estimated at more than one million dollars. In Manitoba the gopher population in certain areas as have been surveyed, has been estimated at 20 animals per acre, and the damage caused has been conservatively estimated at fifty cents per rodent each year. The lose per acre thus occasioned may mean all the difference between a comfortable profit and a heavy loss on the years crops. In addition to the direct loss inflicted by gophers upon crop growth, the mounds of earth thrown up during their tunnelling operations increase considerably the expense of working the land and gathering the harvest. There is further the possibility of such common rodents serving as alternate hosts, or as the direct carriers of organisms pathogenic to higher animals. Citellus beechyi in California has been shown to be susceptible to Pasteurella pestis of bubonic plague, and to be capable of acting as host to murine species of Ceratophyllus through whose agency the disease is conveyed to man. Whilst the possible establishment of bubonic plague in the Canadian prairie areas would seem to be remote, the similarity of climatic conditions in Western Canada to those in the endemic areas of bubonic plague in Manchuria and the fact that the latter disease is essentially one of ground rodents through whose ectoparasites the disease is conveyed to man, must not be overlooked. The effect from a parasitological standpoint of the practice used by some mink ranchers, of feeding fur bearing animals upon small mammalia has not been experimentally investigated, but is another point worthy of consideration. Now there can be little doubt that artifical methods of controlling ground rodents - trapping, poisoning, burrow fumigation - have not in the past yielded results commensurate with the immense expense involved. In Manitoba a sum of approximately $5000.00 has been spent as a bounty upon gophers, and an approximate total of 100,000 gophers has been destroyed in one year, but there is no evidence that any serious diminution has been thereby brought about in the gopher population...