Mosquito feeding behavior determines the degree of vector-host contact and may 
have a serious impact on the risk of pathogen transmission, including that of 
the West Nile virus (WNV). To measure the role of Culex mosquitoes as WNV 
vectors, host-seeking females were collected using animal-baited traps 
containing live birds (quail) or mammals (rabbits) and CO2-baited Center for 
Disease Control and Prevention traps placed in several wetland areas in the 
Czech Republic. Culex pipiens (L.) and Culex modestus (F.) were the most 
frequently collected species. Although Cx. modestus did not distinguish between 
baits, Cx. pipiens was collected significantly more frequently in bird-baited 
traps. Based on mitochondrial DNA analysis of bloodmeals from engorged females 
collected by CO2-baited traps situated within reed beds, a diverse group of 
birds were the predominant hosts (93.7%), followed by mammals (4.2%) including 
humans, and amphibians (2.1%). Among birds, Anseriformes were fed upon most 
frequently by Cx. modestus, whereas Cx. pipiens fed most frequently on 
Passeriformes. To measure the infection risk and confirm the distribution of 
mosquito species in various biotopes, transects of CO2-baited CDC traps were 
operated from wetland reed beds into upland vegetated areas. Even though both 
Culex species occurred in all biotopes sampled and frequently dispersed hundreds 
of meters away from fishpond shore vegetation, the spatial distribution of Cx. 
modestus was significantly associated with reed beds at wetlands. The first 
detection of WNV (subtype RabV) in Cx. modestus in Bohemia and confirmation of 
WNV presence in Cx. pipiens in Moravia together with observed feeding behavior 
supports the presumed role of both Culex species in the avian-to-avian enzootic 
WNV cycle and in avian-to-mammal transmission in the Czech Republic.