They are the only vectors of malaria, yellow fever and dengue to man. They also transmit heartworms in dogs and viral encephalitis in horses. Worldwide there are over 2,500 species of mosquitoes, with about 150 species in the U.S. Mississippi has approximately 60 species. Mosquitoes are perhaps the most successful of all insects. They do not inhabit saltwater.
Mosquitoes are important because of their blood-feeding behavior.
This makes them major nuisances as well as disease carriers. Only the females suck blood - the males are nectar feeders. The females need the protein in blood to produce viable eggs. More money is spent on mosquito control than on control of any other insect. Smaller cities and towns most often have programs using personnel with other duties in addition to mosquito control.