The distribution of I. gemina includes small, shallow ponds, marshes, and canals in the San Francisco Bay Area from Pt. Reyes, Marin Co., south to Santa Cruz Co.. California, United States. All but one of the habitats discovered after 1978 are in urban areas and are liable to habitat alteration. The previously unknown andromorph female is described and compared with the male and heteromorph female. A key for the identification of female Ischnura from the San Francisco Bay Area is provided.