Bloodfed female Aedes aegypti were exposed to a surface treated with pyriproxyfen at 1.0 g m2 for 30 min and then allowed to lay eggs in cups of water containing 4th-instar larvae. Adult emergence from the immatures was highly inhibited, and transmission of pyriproxyfen from the females to the water was revealed. The transfer of the chemical to the water decreased with time before the blood meal. Chemical analysis for pyriproxyfen on the exoskeleton of treated females demonstrated the rapid disappearance of the compound. Pyriproxyfen obviously affected egg maturation of females treated before blood meals, as the number of eggs deposited decreased concurrently with the number of days before the blood meals.