All mosquitoes develop in still or very slow moving water. They evolve through four stages: egg, larva, pupa and adult. There are at least fourteen species of mosquitoes found within our District. Some mosquitoes lay single eggs, which float on the water’s surface. Others species lay their eggs in batches, which float on swamps and ponds. The most pestiferous mosquitoes lay eggs on damp ground. The eggs hatch with accumulated rain, rising river currents, or the flooding of irrigation water in marshy ponds, ditches, woodland pools, and irrigation fields. Eggs can remain viable for several years and not all will hatch during the next flooding.
Mosquito larvae live just below the water’s surface, breathing 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. They 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 the water temperature and the mosquito species.
Usually adult mosquitoes are less than quarter 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 mouth part (proboscis), and scales along the wing veins.
To mate, the male mosquitoes form swarms that attract female mosquitoes. The female's high-pitched humming beat of their wings enables the males to easily locate them. Generally, female mosquitoes mate only once in their lifetime. Afterwards, some species remain within a few hundred feet, while other species will disperse over many miles.
Most male mosquitoes live for a week however most females may survive for a month. While both male and female mosquitoes feed on nectar from flowers, only the females need a blood meal 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 will survive the winter in the egg stage. Although some may spend the winter, as hibernating adults, in a protected location.
The Aedes vexans, Ochlerotatus dorsalis, Culex tarsalis, and Culex pipiens
are the most common species found in the Grand Valley.