This checklist of the mosquitoes of Idaho updates the list of Brothers ( 1971 ), adding 5 species.From the literature, 3, Ochlerotatus mercurator, Ochlerotatus nevadensis, and Ochlerotatus punctor, are addedand 1, Ochlerotatus stimulans, is deleted. We are reporting 2 new state records, Ochlerotatus decticus andOchlerotatus euedes, and extending their ranges westward in the United States. One new genus and 2 newsubgenera are also added.