Since being detected in Missouri in 2002, the number of human cases of WNV declined annually through 2005. However, this downward trend in the number of reported human cases in Missouri was reversed in 2006 when 61 cases of West Nile Fever and three deaths due to West Nile encephalitis were reported. The unexpected increase in human cases underscores a concern that WNV may continue to be a serious human health risk throughout the western hemisphere. The risk of exposure to West Nile virus is highest for those who are most likely to encounter infected mosquito vectors. The risk of encounter with an infected mosquito increases with the abundance of mosquitoes in the peridomestic environment and the amount of time a person spends in this environment. The abundance of infected mosquitoes in the peridomestic environment is related to the population dynamics, feeding preferences, and survivorship of key mosquito species along with the presence of suitable hosts and favorable environmental conditions. With these facts in mind, a research project was was undertaken to address several aspects of mosquito bionomics. The first phase of this project, completed in 2007, was to examine the temporal dynamics, species composition, and relative abundance of central Missouri mosquito populations in relation to climatic and environmental variables (e.g., temperature, relative humidity, wind, rainfall, and qualitative rating of habitat with regard to oviposition sites and resting sites). This information was integrated into a predictive model of “risk” with regard to the likelihood of mosquito encounters and encounters with key vector species.