A female Anopheles mosquito normally mates only once in her lifetime. It usually requires a blood meal after mating before her eggs can develop. While the blood meal is not essential for the survival of female mosquitoes, it is crucial for successful egg production and egg laying. Blood meals are generally taken every two to three days, before the next batch of eggs is laid. About 100 to 150 eggs are laid on the water surface during oviposition (egg laying). Oviposition sites vary from small hoof prints and rain pools to streams, swamps, canals, river beds, ponds, lakes and crop fields. Each species of mosquito prefers different types of habitats to lay eggs. Under the best conditions in the tropics, the average lifespan of female Anopheles mosquitoes is about three to four weeks.