An ovitrap containing hay infusion and a second ovitrap adjacent to it containing a 10% dilution of the infusion in tap water together yielded 8 times more Aedes aegypti eggs than single CDC ovitraps containing tap water. These "enhanced pairs" were significantly more attractive than pairs with other combinations of infusion, water or methyl propionate, and have proven useful for daily monitoring of Ae. aegypti populations. Our results shed light on the oviposition behavior of Ae. aegypti in the field.