Mosquitoes are a bit like flying syringes. Their large needle nose, called a proboscis, is ideal for quickly landing on a victim, withdrawing a bit of blood and then taking off for the next target. You may not notice a mosquito bite initially, but within an hour or two after a bite, you may have raised red bumps from mosquito bites that itch like crazy.

When a mosquito bites, she leaves behind saliva. In fact, the saliva present in mosquito bites serves the mosquito well, since it works as an anti-coagulant. These means the mosquito can quickly draw blood without catching your attention.

The saliva injected when a mosquito bites causes our bodies to produce a histamine response. We have a slight allergy response, and thus our skin around the bite area gets itchy. This can actually be a good thing, even if it’s an annoying one, because mosquito bites can transfer disease. In the US, risk of West Nile Virus is the main concern. In other countries, mosquito bites may transfer malaria and other quite nasty germs. If our bodies didn’t respond with the itch factor to mosquito bites, we might not realize we’d been bitten. Though knowing you’ve been bitten may not prevent the spread of disease, you can tell your doctor about it if you develop severe flu symptoms a few days or weeks later.

Some people build up a tolerance to mosquito bites. They may barely notice when they’ve been bitten, and the skin may not swell up. This is sort of like getting allergy shots. Small doses of mosquito saliva over time can cause us to become immune to the saliva. Adults more typically have less of a reaction to mosquito bites than do children. This immunity can wear off after a while, and an adult who hasn’t had mosquito bites for a few years might become itchy again after receiving a few new mosquito bites.

Other people may have strong allergic reactions to mosquito bites. These are not usually anaphylactic shock reactions, like those caused by bee venom in people allergic to bees. Instead the skin may develop blisters, bruises or scabs. A child with an allergic reaction to mosquito bites can look almost like he or she has a case of chicken pox. It can help people with extremely itchy mosquito bites to use oral antihistamines or topical antihistamine creams on bites. People who have a lot of bites and swelling from bites should be watched for possible infection of the bite sites.

Since mosquito bites can cause more than an itch, it’s a good idea to avoid them when you can. Mosquitoes are most active during the hours just before and after sunrise and sundown. It can help to wear protective clothing (though some mosquitoes can drill right through clothing) and insect repellent if you’re in areas with large mosquito populations. Also screening windows and keeping doors shut can keep mosquitoes out of your home.