With the introduction of West Nile Virus to the Americas there has been a greatly renewed interest in mosquito control among equestrians. But the fact is that other important viral encephalatides (eastern equine encephalitis, western equine encephalitis, and venezualan equine encephalitis) and many other important animal and human diseases are spread by this annoying, and sometimes life threatening, little insect. This article discusses management techniques to try and decrease you and your horse's exposure to the mosquito.

Successful mosquito control requires a knowledge of where and how they develop. All mosquitoes pass through four life stages: egg, larva, pupa and adult. The first three stages must have water for development. Mosquitoes can complete their life cycle in less than a week when the weather is very warm or development can be extended to several months when cool. It is the eggs of mosquitos that overwinter in climates with cold winters.

Depending on specie, there are several different egg-laying habits. Mosquitoes of the Culex group lay their eggs on the surface of water in rain barrels, bird baths, tin cans, old tires, car bodies, cisterns, roof gutters and any other container which holds water. Mosquitoes of the Aedes group deposit their eggs at the base of vegetation bordering streams or in low lying areas subject to flooding. Also, this group can deposit their eggs above the water line in artificial containers (such as tin cans, old tires, etc.) or in tree holes that hold water. These eggs will hatch when exposed to water.

After the eggs hatch, the larval stage begins. Mosquito larvae are often called "wrigglers.” Wrigglers are most commonly seen just below the surface of the water. Many species breathe through a tube (siphon) that extends upward from the end of their bodies toward the water surface. The larvae feed on microorganisms found in the water and grow rapidly, eventually passing through four molts. After the fourth molt has taken place, the mature larvae transform into pupae. Mosquito pupae are also quite active and are often called "tumblers" because of their tumbling motion in water when disturbed. After a few days the pupae transform into adults. The adult male mosquito feeds only on nectar and plant juices whereas, the females are blood feeders and generally require a blood meal before they can lay eggs.