Hematological values in deer mice in relation to botfly infection

An incidence of 31.8 percent infection with botflies (Cuterebra sp.) was found in a population of deer mice (Peromyscus leucopus noveboracensis) trapped near the Queen's University Biological Station, Chaffey's Locks, Ontario, during July and August 1958. No infections were observed in mice trapped prior to 23 July. Infected mice had significantly lower hemoglobin concentrations and packed cell volumes than noninfected mice trapped during the same period. The possibility that reduced blood values resulting from myiasis might lower physiological resistance to environmental stressors sufficiently to contribute to population declines is considered.