Between 1980 and 1984, field studies were conducted in 2 areas on the Delmarva Peninsula to identify the presence of La Crosse (LAC) virus. Ovitraps were used to collect eggs of Aedes triseriatus complex mosquitoes. No virus was obtained from 969 pools containing 22,370 adult mosquitoes reared from eggs. Only 1 of 143 raccoon serum samples had neutralizing antibody to LAC virus; 36 sentinel domestic goats, and 99 other wild mammal serum samples were negative. The apparent absence of LAC virus may be due to the uncommon occurrence of the eastern chipmunk, a species which has been shown to be an amplifying host for this virus, on the Peninsula.