C. F. Hodge (1911) calculated that a pair of house flies beginning operations in April could produce enough flies, if all survived, to cover the earth 47 feet deep by August. This, of course, is an ecological absurdity but it does convey some idea of the tremendous reproductive potential of some insects. If one can reverse for a moment the usual focus on insects as enemies of man, Hodge's layer of flies represents an impressive pile of animal protein.