Anopheles walkeri was described by Theobald (1) in 1901 from a number of females collected by Professor E. M. Walker at Lake Simcoe, Ontario, Canada. All the females were taken from “beds of reeds close to the marshy shore of Lake Simcoe.” No males or larvae were taken at that time. Howard, Dyar and Knab (2) re-described the female and recorded a rather wide distribution of the species from Ottawa, Ontario, Massachusetts, Virginia and Arkansas. The larva and male remained unknown. Dyar (3) gives no further information regarding this species but adds Michigan and the District of Columbia as new records of distribution. Matheson and Shannon (4) recorded the discovery of the larvae and males from a cattail marshy area at North Fairhaven, New York, on the southern shore of Lake Ontario. They stated that this mosquito was very abundant and during July (1922) was one of the worst pests in that region.