Most mosquito species prefer to lay eggs at the edge of water bodies against mulch, grass, foliage or refuse that will hold the eggs at the surface of the water. If the water evaporates – or you pour it out – before the eggs develop, which usually takes about 7 to 10 days, the eggs will not develop completely into adults, and they will die. If water is not present, those eggs can sit for months until there is enough water to float the eggs to develop and feed the larva. That is why, even though much of the country is in a drought, mosquitoes are still active.