Inhibition of the replication of alternate California serogroup bunyaviruses in Aedes triseriatus mosquitoes has been observed for mosquitoes previously infected with La Crosse (LAC) virus. By contrast, prior infection of mosquitoes with LAC virus did not interfere significantly with the subsequent infection and replication of Guaroa bunyavirus (Bunyamwera serogroup), or heterologous viruses such as West Nile flavivirus, or vesicular stomatitis rhabdovirus.