Project Summary West Nile virus (WNV) is a mosquito-borne flavivirus, and the leading cause of domestically-acquired arboviral disease in the United States, resulting in significant disease and death every year among humans and other animals. Efficacious, vector-targeted interventions are critically needed, but current vector control methods (primarily insecticides sprayed into the environment) have been inadequate for WNV control. We have been developing and testing stations that contain endectocide-treated bird feed as a way to control WNV transmission to humans in the western U.S., the region which suffers from the highest incidence WNV disease in North America, by targeting the primary bridge vector mosquito, Culex tarsalis. This project is designed to develop endectocide-treated birdfeed as a novel, safe and scientifically-validated way to control the risk of West Nile virus transmission to humans in the western U.S. The concept is that birds will self-medicate by birdfeed stations containing the treated feed, which would be placed as arrays on homeowners' properties, in neighborhoods or in parks. The blood of treated birds would then kill the primary mosquito vectors of West Nile virus that blood feed on them, which would lower the risk of West Nile virus transmission to people who live, work and recreate around the birdfeed stations.