Female Aedes albopictus and Aedes epactius infected by inoculation with St. Louis encephalitis (SLE) virus transmitted virus transovarially to their F1 progeny. With Ae. epactius, minimal infection rates (MIR) in F1 larvae were similar for progeny reared at 18 (+/- 1) degree C or 27 (+/- 1) degree C, whereas, MIR's were significantly higher in F1 adults reared at 18 degrees C, than they were in F1 adults reared at 27 degrees C. Use of different strains of SLE virus appeared to influence transovarial transmission of virus by Ae. albopictus, but not by Ae. epacticus. Transovarial transmission of SLE virus was not demonstrated with colonized strains of Aedes dorsalis, Ades sierrensis, Ades triseriatus, Ades vexans, Culex pipiens, Culex quinquefasciatus and Culex tarsalis, and field strains of Ae. vexans.