The number of cases of encephalitis caused by La Crosse virus recently has increased insouthwestern Virginia counties. This article presents results of a study conducted from May to September 2000in Wise County, VA, that examined the area-wide oviposition activity and habitat preferences of Ochlerotatustriseriatus and Aedes albopictus, potential vectors of La Crosse virus in the region. Data from 490 ovitrapcollections made throughout the county showed that mean oviposition activity throughout the study was higherfor Oc. triseriatus (20.4 eggs/trap-day) than for Ae. albopictus (3.7 eggs/trap-day). The 2 species also had distincthabitat preferences for oviposition, with Oc. triseriatus favoring forested habitats and Ae. albopictus favoringurban/residential habitats. A landcover map of 6 habitat types derived from Landsat satellite imagery of thecounty showed that 63% of the county was forested and l8% was urban/residential. A Bayesian decision-rulemodel that incorporated the ovitrap data and landcover map was moderately successful at predicting the occurrenceof high oviposition activity and abundance of the 2 species. The predictions reflected seasonal and spatialfluctuations in oviposition activity, with accuracies between 55 and 79% for Oc. triseriatus and 70 and 94% forAe. albopictus. Kappa (K)l, a measure of the predictive power of the model, varied from poor (K < 0.4) to good(O.4 < K < 0.75) for both species, and was highest during periods when actual egg abundance was high. Thissuggests that the predictions were most accurate during periods when the risk for La Crosse virus transmissionis greatest. Limitations and suggestions for improving the model are discussed.