Most people never notice their first mosquito bites. After being bitten several times, though, you're likely to start noticing, often almost immediately after the mosquito feeds. The signs include:
- A puffy, white bump that appears a few minutes after the bite
- A hard, itchy, reddish-brown bump, or multiple bumps, appearing a day or so after the bite or bites
- Swelling around bites
- Small blisters instead of hard bumps
- Dark spots that look like bruises
In children and people with immune system disorders, mosquito bites sometimes trigger:
- A large area of swelling and redness
- Low-grade fever
- Swollen lymph nodes
When to see a doctor
If mosquito bites seem to be associated with more-serious signs and symptoms — such as fever, headache and body aches — contact your doctor.
Mosquito bites are caused by female mosquitoes feeding on your blood. Female mosquitoes have a mouthpart made to pierce skin and siphon off blood. Males lack this blood-sucking ability because they don't produce eggs and so have no need for protein in blood.
As a biting mosquito fills itself with blood, it injects saliva into your skin. Proteins in the saliva trigger a mild immune system reaction that results in the characteristic itching and bump.
Mosquitoes select their victims by evaluating scent, exhaled carbon dioxide and the chemicals in a person's sweat. There's conflicting evidence about whether mosquitoes prefer women or men.
Because most adults have had mosquito bites throughout their lives, an adult is less likely to have a severe reaction than is a child.
Mosquitoes can act as reservoirs of diseases such as West Nile virus, malaria, yellow fever and dengue fever. The mosquito obtains a virus by biting an infected person or animal. Then, when biting you, the mosquito can transfer that virus or parasite to you through its saliva. West Nile and encephalitis viruses are found in the United States. Dengue fever, although it is rare, has been reported in the southeastern United States. Other diseases, such as malaria and yellow fever, are far more common in tropical areas of the world.
You can take a number of steps to limit your exposure to mosquitoes and protect yourself from bites when mosquitoes are unavoidable.
Use insect repellent
Most insect repellent products applied to the skin contain one of three active ingredients:
- Picaridin (also called KBR 3023)
- Oil of lemon eucalyptus (a plant-based compound)
These repellents temporarily keep hungry mosquitoes from identifying you as a food source. The higher the concentration of DEET or picaridin in a product, the longer its protection will last. An application of a standard oil of lemon eucalyptus product protects you about as long as a product containing DEET at a low concentration.
Used according to package directions, insect repellents are generally safe for children and adults, with a few exceptions:
- Don't use DEET-containing products on infants younger than 6 months.
- Don't let young children get DEET or picaridin-containing products on their hands or faces.
- Don't use picaridin or oil of lemon eucalyptus on children under age 3.
- Apply repellent only to exposed areas of skin — not under clothing.
- When you go indoors, wash with soap and water to remove any remaining repellent.
Treat clothing and outdoor gear
Permethrin is an insecticide and insect repellent recommended for use on clothing and outdoor equipment. You apply a permethrin product directly to the clothes and fabric-covered equipment you want to protect. Because many brands of permethrin-based insect repellent are available, check the product label for specific application instructions. Some sporting goods stores sell clothing pretreated with permethrin.
Wear protective clothing
When you're in an area with lots of mosquitoes, wear:
- Long sleeves
- Long pants, possibly tucked into the tops of your socks
- Light colors
- A wide-brimmed hat to help protect your ears and the back of your neck
Reduce mosquitoes around your home
Mosquitoes need standing water to breed. To keep your house and yard free of mosquito pools:
- Unclog roof gutters.
- Empty children's wading pools at least once a week, and preferably more often.
- Change water in birdbaths at least weekly.
- Get rid of old tires in your yard.
- Empty outdoor flower pots regularly or store them upside down so that they can't collect water.
- Drain your fire pit if water collects there.