Why do Mosquitoes Bite?

Only female mosquitoes bite, though all mosquitoes live on the sugar found in plant nectar, not on blood. Female mosquitoes bite to obtain necessary proteins from blood so they can produce eggs. Proteins in human and animal blood are necessary for the female mosquito to produce fertile eggs; since males cannot produce eggs they have no need for blood. Females require a new blood "meal" for every nest they lay, and produce about 250 eggs per meal.

Mosquitoes have been evolving for 30 million years, and have developed an impressive array of sensory receptors. They possess chemical, visual, and heat sensors, all designed to zero in on a blood source.

The chemical sensory receptors are located on the antennae, which allow mosquitoes to detect carbon dioxide. All mammals give off carbon dioxide, including humans; the gas is excreted through the skin and is exhaled with each breath. A mosquito can detect this scent from 100 feet (30 meters) away.

Female mosquitoes, unlike males, have a proboscis, which is a long, thin, needle-like syringe located at the mouth. This syringe allows the female mosquito to pierce her victim and fill her abdomen with the victim's blood. At the same time, when mosquitoes bite they inject a small amount of saliva that thins the incoming blood so it doesn't clot in the narrow channel of the proboscis.

When a mosquito is done feeding, some of its saliva remains in the wound and causes an immune system response, which often results in itching. A welt forms, known as a wheal, and the body goes to work breaking down the proteins from the saliva. The bite will continue to itch until the body has broken down all of the proteins, which generally takes 24 hours, but can vary depending on the person. Some oral medications, such as Benadryl, and several skin ointments, such as calamine lotion, are known to help reduce the itchiness caused by mosquito bites; the Internet also offers an array of mosquito bite home remedies.

Unfortunately, some people are bitten by mosquitoes more often than others. While scientists have yet to pinpoint the exact reason mosquitoes bite specific people, there are some well-known factors that play a role: giving off large amounts of carbon dioxide; wearing deodorant, perfume, cologne, or lotion; being outside at dusk; and wearing dark colored clothing. Overall, mosquitoes are attracted by smells, which often means more mosquito bites.

Mosquitoes can carry diseases that can be transferred to humans through their bite, some of which are malaria, encephalitis, West Nile virus, yellow fever, and dengue fever; insect repellents containing the active ingredient DEET reduce the chance of catching a disease. Repellents work by confusing the chemical receptors of the mosquito so that they cannot zero in on the source of the carbon dioxide.

When DEET is used according to the label instructions, it generally does not cause any health concerns; however, if the product is misused, there is a chance that serious side effects, such as headaches and weakness, can occur. Some health professionals urge people to use DEET sparingly, to avoid using it on children, and to never use it on infants, as the skin of young children and infants more easily absorbs chemicals that can lead to side effects. DEET repellents are very popular can be purchased from most drug stores, outdoor stores, and on the Internet.

Reducing the mosquito population naturally prevents mosquito bites and can be done by preventing standing water from collecting: flowerpots, trash lids, and anything deep enough to collect a puddle of water can be a mosquito breeding ground. Fountainless birdbaths or any other necessary standing water should be flushed with the hose every few days, while mosquito larva found in fishponds are often eaten by the fish. Some outside products, such as candles and tiki torches, also contain mosquito repellent to deter the insects.