Two isolates of La Crosse virus were obtained from 515 Aedes triseriatus larvae collected during June and September 1972. The first isolate was from a pool of 43 larvae collected from a basal tree-hole in Iowa County, Wisconsin on 7 June 1972. The second isolate was from a pool of 40 larvae subsequently collected from the same tree-hole on 2 September 1972. A. triseriatus has been repeatedly shown to be infected with La Crosse virus, has transmitted the virus efficiently in the laboratory, and is closely associated with the vertebrate hosts during the period of virus transmission. Isolation of La Crosse virus from larvae of A. triseriatus suggests that this species may possibly serve as an overwintering reservoir for La Crosse virus.
On leave of absence from the Faculty of Graduate Studies, Mahidol University, Bangkok, Thailand.