Population size and probability of daily survival of adult Aedes triseriatus were measured in a 0.03 ha section of scrap tireyard in South Bend, Indiana, using single-release, multiple-recapture methods. Average population size estimates ranged from 1,349 to 4,492 females (999 males in one experiment), demonstrating that population densities of Ae. triseriatus can reach levels in tireyards far exceeding densities in woodlots. The probability of daily survival was equivalent between males and females (0.78-0.82). When laboratory-reared small and large mosquitoes were released, small mosquitoes of both sexes were recaptured at lower rates than large mosquitoes, suggesting that experimental populations of small and large mosquitoes behave differently once released into the field, but that mark-recapture methods may not be sensitive enough to detect differences in survivorship.