Before 1970, Culexocossa was considered a synonym of Culex aikenii (Aiken & Rowland) (Stone et al. 1959), but Belkin (1970) revalidated it along with Culex panocossa Dyar, a species not found in Argentina, and the name aikenii was relegated to nomen dubium. Culex ocossa was not listed from Argentina by Knight & Stone (1977)." (Mitchell & Darsie, 1985).

Disease relations: The species may be involved in the transmission of Western Equine Encephalitis virus (WEEV) in Chaco and Corrientes provinces (Sirivanakarn & Jakob, 1981). The WEEV, Para and Venezuelan Equine Encephalitis viruses were isolated from specimens of Culex ocossa between 1977 and 1980 in Chaco Province (Mitchell et al., 1985). However, the epidemiologic importance of Culex ocossa may be underestimated as it was considered synonymous with Culex aikenii until 1970. As a result, many virus isolations were made from specimens identified as Culex aikenii. The latest, was found naturally infected with a wild strain of Venezuelan Equine Encephalitis (VEEV), and was infected and was able to transmit the VEEV in laboratory conditions (Galindo & Grayson, 1971; Galindo, 1972; Galindo & Adames, 1973).

Immatures have been found in permanent habitats including lakes, rivers and swamp margins in forests, gardens and along the sides of roads usually with abundant floating vegetation (Pistia, Eichhornia, Salvinia, Azolla) associated with Culex delpontei and Culex pereyrai in Brazil. Adults are nocturnal and feed on humans. The blood meal identification by the precipitin test of engorged Culex ocossa indicated that these mosquitoes feed on mammals and birds.