From Ohio History Central
There are about 2,700 species of mosquitoes in the world. Sixty of these live in Ohio. Mosquitoes (Culex pipiens, northern house mosquito) are small, slender flies with two narrow wings, long legs, and piercing-sucking mouth that is used to pierce your skin and drink blood.
Female lay her 100 - 300 eggs on the surface of water, which in one to five days. The larvae hang at an angle in the water, filtering food out of the water. Larvae eat plankton. These "wigglers" change into pupae until, after a few days, the metamorphosis is complete and they become adults. The 1/6 - 1/2 inch adult mosquitoes are most active during the evening and early morning. Mosquito habitat includes permanent or temporary water sources, in particular areas with stagnant water. Adult males feed on plant juices; adult females feed on animal and human blood, each traveling great distance from their breeding grounds
To feed, female mosquitoes insert their sucking mouth parts, injecting anti-coagulants to keep the blood flowing freely. It is when the human body tries to break down and get rid of these chemicals that they feel the itching sensation associated with mosquito bites.
Mosquito bites are not only irritating; they can sometimes be dangerous, carrying diseases from food source to food source. Many species of mosquitoes have been known to carry diseases like malaria and encephalitis. More recently scientists have associated them with the transmission of the West Nile virus.
The best control of mosquitoes is to get rid of stagnant water by draining areas and objects such as tires, unused swimming pools, buckets and anywhere else that may hold water. Although irritating to humans, mosquitoes area beneficial food source for a variety of wildlife, including birds, amphibians, bats, and the diving beetle.