Agricultural Extension Service, South Dakota State College
Each year the Norway ( or brown) rat and the common house mouse consume thousands of bushels of grain and other foods on South Dakota farms. They attack grain in the field and in farm storage. At the time they consume the grain they also pollute and contaminate it by their droppings, urine and hair. Every 24 hours each rat voids an average of 70 pellets and about 15 cc of urine. Such contamination makes food grains subject to seizure by the Food and Drug Administration because they are unfit for human use. The monetary losses resulting from such seizure of wheat may run as high as $1.00 per bushel. These rodeiits also attack poultry and livestock, carry diseases to man and livestock, destroy property by gnawing and burrowing and cause fright or embar: rassment by their presence. The total loss from rats alone has been estimated at about $20.00 per rat per year. One does not have to search long for reasons to control rats and mice.
Lofgren, John, "Rat and Mouse Control on the Farm" (1957). SDSU Extension Circulars. 685.