Oviposition traps were used to follow changes in the population of Aedes aegypti (L.) (Diptera:Culicidae) in a seven-block area in midtown region of Tucson, Arizona. About 20,000 eggs were collected over a period from 1 June to 14 October 2000. Peak mosquito populations were correlated with the late summer rains. Mosquitoes seeking a blood meal were collected and dissected to determine if they had previously fed, i.e. if they were parous. Of the 241 females examined, 44% were parous, with a range from 0% to 80%. Females that had blood in their guts were collected and the source of blood was identified using an ELISA. Preliminary results suggest that 80% of them had fed on humans. These data suggest that the reproductive history of Tucson populations of Ae. aegypti could be conducive for transmission of dengue viruses.