All Mosquitoes develop in still or very slow moving water. Mosquitoes develop through four stages: egg, larva, pupa and adult. There are at least fourteen species of mosquitoes found locally within the District. Some mosquitoes lay single eggs that float on the water’s surface. Others types lay their eggs attached in batches that float on swamps and ponds. The most pestiferous mosquitoes lay eggs on damp ground that periodically floods. The eggs hatch when rain, rising river currents or irrigation water flood marshy ponds, ditches, woodland pools and irrigation fields. Eggs can remain viable for several years and do not all hatch with the next flooding.
Mosquito larvae live just below the water’s surface and breathe directly from the surface by means of a siphon tube located on the rear of their bodies. Larvae feed on small organic particles suspended in water and grow by molting four times with the final molt resulting in a non-feeding pupal stage. After the transformation is complete, the new adults split the pupal skin and emerge. The development of larvae to adult stage requires 6 to 10 days depending on water temperature and the mosquito species.
Adult mosquitoes are usually less than 1/4 of an inch long with long slender legs and a single pair of wings. They can be distinguished from all other flies by the presence of a long piercing mouthpart (proboscis) and scales along the wing veins.
Mating is preceded by male mosquitoes forming swarms that attract female mosquitoes. The high-pitched humming of their wing beat enables the males to easily locate them. Female mosquitoes usually mate only once in their lifetime. Afterwards some species remain within a few hundred feet and other species can disperse over many miles.
Male mosquitoes usually live for a week and females may survive for a month. While both male and female mosquitoes feed on nectar from flowers, only females bite to obtain a blood meal needed for egg development. Female mosquitoes are attracted to carbon dioxide, odors, moisture and body heat all of which people give off in quantity when active. Female mosquitoes deposit 75 to 500 eggs in a single batch. Most mosquito species survive the winter in the egg stage and others spend the winter as hibernating adults in protected location.