Adult female Aedes aegypti that were reared on a suboptimal diet as larvae were less likely to engage in host-seeking behavior than were adults derived from larvae reared on an optimal diet. A postemergence carbohydrate diet of either 1 or 10% sucrose solution did not affect this response. When the progeny of field-collected Aedes vexans were reared in the laboratory, the adults were significantly larger than their parents. This indicated that the larvae of the field population were not as adequately nourished as their laboratory-reared progeny.