Mosquitoes are blood-sucking insects that are attracted to moisture, sweat, heat, and carbon dioxide. They are attracted to some people more than others. Mosquitoes most often feed from dusk to dawn.

Mosquitoes carry disease in some parts of the world. They are carriers of the West Nile virus and may transmit the virus to humans and animals. West Nile virus causes an infection that can lead to inflammation of the brain (encephalitis) or the tissues surrounding it and the spinal cord (meningitis). Mosquitoes in Africa as well as other parts of the world may carry malaria or yellow fever. Mosquitoes do not carry the human immunodeficiency virus (HIV).

Symptoms of a mosquito bite may last for hours, days, or even weeks. Common symptoms that begin immediately are:

• Reddened skin.
• A swollen lump (wheal).
• Itching.

Staying indoors at dawn and dusk and in the early evening, coupled with wearing long-sleeved shirts and long pants when outdoors, may lower the risk for mosquito bites. Insect repellent, applied sparingly to skin and sprayed on clothing, may keep mosquitoes away.