Technical Abstract: Scientists in the USA seek to develop Global Information Technology (GIS, GPS, remote sensing)-based systems that can be used to deploy sentinel traps for mosquito vectors and for the implementation and evaluation of mosquito control. Achieving this objective requires the development of methods for unbiased estimation of adult mosquito density. Unbiased estimators will enable the identification and analysis of natural mosquito dispersion parameters and the development of GIT-based models for forecasting mosquito activity and distribution. In North America, the CDC light trap (augmented with attractant CO2 gas) is used to determine the species composition and abundance of vector populations, as well as the geographic distribution and virus infection rate in these populations. But we do not know the relationship between mosquito capture rates by CDC traps and the numbers of mosquitoes attacking the human population. In the present study, the landing rates (LR) of Anopheles quadrimaculatus, Culex nigripalpus, Cx. quinquefasciatus, Ochlerotatus triseriatus and Aedes albopictus on human hosts were compared with capture rates of the same species by CDC traps (with CO2). We found significant associations (P '0.05) among the day-to-day responses to LR and CDC by An quadrimaculatus and Cx. quinquefasciatus, and among the hour-to-hour (over 24 hours) responses of all species except Oc. triseriatus. CDC traps typically underestimate LR by 40-125%, depending on the mosquito species and time of day, but improved precision (R2 =0.61-0.70) in these estimates is achieved by the identification/removal of outlier responses and the fit of log-transformed LR data for each species to linear or polynomial models. Temporal variations in the capture rate of mosquitoes by LR and CDC suggest that each method samples separate components of the mosquito population and/or differentially stimulates competing response patterns in individual female mosquitoes.