Only female mosquitoes suck blood from other animals. Females do this because egg production requires protein, which is readily found in blood fluid.
Mosquitoes are insects that belong to the order Diptera, or true flies. All true flies have two wings, but a mosquito's wings, unlike other true flies, are covered with scales. These true flies have a four-stage life cycle: egg, larva, pupa and adult.
Mosquitoes breed in wet areas, with many species using stagnant bodies of water to lay their eggs, which float on the surface. Ponds, wetlands, old tires, tin cans, creeks and catch basins are perfect areas for them to lay eggs. Mosquitoes, depending on the species, either lay single eggs or groups of attached eggs, known as "rafts." Eggs will usually hatch into larvae within two days, but they have the ability to withstand winter freezes. Water is essential to their breeding and survival.
Cui, whose research focuses on mosquitoes, said that because water is so important, weather conditions also play a large role in mosquito populations.
"Rainfall is a major factor," Cui said.
He said local populations would be affected because precipitation levels in the area are low.
"Quite frankly, with the drought conditions, we have not found any [mosquito] larva in the State College Borough," Mark S. Henry, State College health officer, said.
Cui added that human-made contraptions, such as dog bowls and swimming pools, are potential breeding grounds for the mosquitoes.
Larvae live in bodies of water from four days to two weeks. Larvae shed their skins four times in a process known as molting and become larger after each molt. The larvae feed on organic matter and microorganisms in the water and must go to the surface for oxygen, which they collect using a tube called a siphon. The larvae enter the pupal stage after the fourth molt.
The pupal stage is the time when mosquitoes change into adults. It is a time of resting, and the pupae do not feed during this time, but, when disturbed, will "tumble" toward safety into deeper waters, hence the nickname "tumblers." Similar to the cocoon stage of butterflies when they change from caterpillars into adult butterflies, the pupae transform into adult mosquitoes once development is complete, which can take from one to four days, according to the American Mosquito Control Association's (AMCA) Web site.
Adult mosquitoes rest on the surface of the water for a short time to let all of their body parts harden and to also allow for the wings to dry out properly. Once complete, mosquitoes will wait a few days before mating and sucking blood.
Amy Kelchner, spokeswoman for the Pennsylvania Department of Health, said residents should take the West Nile virus seriously, but also keep it in perspective.
"It's here to stay, and it's not unexpected," she said. "First, if you are bitten by a mosquito, keep in mind that only a small percentage of mosquitoes have the virus. Second, most people who contract the virus won't even know they have it. And third, out of those who know they have West Nile, only one out of 150 will ever need medical attention," Kelchner said.
With the already small percentage of mosquitoes harboring West Nile, the drought conditions affecting State College and other locales throughout the state mean an even smaller number of mosquitoes have the virus.
Kelchner said it is important for residents to get rid of standing water around homes to control mosquito populations.
"The DEP will spray infested areas when necessary," Kelchner said, but added that residents need to control areas of standing water on their properties to ultimately help control problems such as West Nile virus.
