The efficiency of the duplex cone and Fay-Prince traps for monitoring adult male and female Aedes sierrensis was evaluated at 3 field sites in California. The numbers of females captured by both types of traps were significantly correlated with human sentinel collections. The Fay-Prince trap captured more Ae. sierrensis females than the duplex cone trap and was a better tool for estimating female activity levels. There was no significant correlation between the number of males captured in Fay-Prince traps and at humans. Male numbers in duplex cone trap collections explained only 27% of the variation in the number of males collected at sentinels, suggesting that neither trap is a robust tool for estimating male activity around humans.