A Word About Mosquitoes
Mosquitoes won’t find rain gardens to be good breeding areas because if a rain garden is properly constructed the water will drain within 24 hours (but usually within an hour or two). The Culex mosquito, the primary variety that can transmit West Nile virus to humans prefers to breed in small, stagnant containers of water. These are usually old tires, pots, birdbaths and pans under planters.
The development of a mosquito, from egg to adult takes 10 to 14 days depending on the air temperature. The warmer the air the shorter time the eggs take to mature. It takes 24 – 48 hours for eggs to hatch. After the eggs hatch the mosquito larva must live in water for 7 -12 days.
Rain Gardens and Mosquitoes (Rutgers)