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June 27, 2013 at 12:29 PMComments: 0 Faves: 0

What Bit Me!? A Summer Guide to Insect Bites

By Jeffrey VanWingen M.D. More Blogs by This Author

A lot of kids come into my office during the summer for sports physicals, bumps, scrapes, and sprains. Looking at the shins of boys always makes me smile. I believe that a vast array of scrapes and insect bites on a boy's legs are evidence of a fun, adventure-filled summer.

Summer is a time when insects feast on our skin. Bites are prevalent, and this often raises the question, "What bit me?"  Well, let's find out!


Mosquito bites and summer go hand-in-hand. Warm, rainy, humid weather provide ideal conditions for larvae to spawn and hatch in standing water. When mosquitoes hit the air, they look for a blood meal to repeat the cycle. Unfortunately, they are attracted to the carbon dioxide that we exhale, and any area of exposed skin is fair game.

When the mosquito bites, it leaves some of its saliva under the skin. While the saliva benefits the mosquito by preventing the blood from clotting, it creates an area of intense inflammation under the victim's skin - the mosquito bite. These bites are pea-sized mounds of red, itchy, inflamed skin. They typically resolve in a matter of days. No sequelae (residual effects) are seen unless repeated scratching causes scarring or opens the door for infection.


Fleas may visit our skin courtesy of an animal friend or the environment. These little guys can find a home in a warm protected place like fur, sand, soil, or carpet.

Flea bites are more prevalent in the lower reaches of the body, like the ankles or shins, where they have hopped on from the ground or pets. They are often found in clusters and may contain a small pus-containing knob (pustule) atop the bump. Like mosquitoes, fleas bite for a blood meal, leaving behind inflammation-inducing saliva. 


Common house flies are annoying, but at least they don't bite! Similar looking relatives, the black fly and the horsefly do, however. These species are quite common across North America and can be present at different times of warmer seasons. Black flies are a particular nuisance because they can arrive in droves without warning and attack incessantly. These fly bites are also driven by a reaction to the insect's saliva. They tend to be larger and broader than mosquito bites. And, like mosquito bites, they are present singularly and randomly across exposed skin, resolving within days. It's difficult for these insects with their big proboscis (biting part) to do so without creating intense pain. For this reason, most everyone knows exactly when, where, and by what they've been bitten when a fly is responsible.

No-see-ums (Flying Midges)

As the name implies, these insects are tiny - often unseen. Like mosquitoes, they are spawned around standing water and are more prevalent around water and after significant rainfall. Due to their size, a bite may or may not be felt. Their size also adds to the insidious nature of these insects because they can often pass through metal screens in windows and doors. Mesh screens are often small enough to keep these insects out. The bites typically look broader than a mosquito bite. They are found anywhere on exposed parts of the body. Unlike larger insects, no-see-ums have no difficulty finding their way though hair to the scalp. The bites may be singular or in clusters, and they may or may not have a pustule atop the bite. 


Fire ants are the most common biting ants in North America, but they are especially prevalent in southern regions. Unlike the above insects who bite for nourishment, fire ants bite for protection. Intrusion into or near a colony will stimulate these ants to attack. Attacks involve the recruitment of multiple ants. Since the ants are on the ground, body parts on the ground are those attacked. 

Bites from these insects are intense. As the name implies, the venom injected into the skin causes an immediate painful burning emanating from the site. The burning lasts for several minutes and then subsides. A red bump follows, which usually contains a pustule. There is never any confusion about the culprit when fire ants bite, as they definitely makes their presence known.


A lot of people show me bites or rashes and declare that a spider must have bitten them during the night. Looking at a minor insect bite, I am usually skeptical that a spider is responsible. When these guys bite, destruction occurs. A spider bite leaves behind venom; the goal of which is to paralyze its meal and start the digestive process, making a nice soup that the spider can enjoy later. 

The potency of a spider bite will vary among the species. In humans, the effects can range from redness, inflammation, and bruising to paralysis, muscle spasms, and a large cavity of dead tissue. 

The most feared spider bites are the black widow and the brown recluse. These bites should prompt immediate medical attention. If you live in an area where brown recluse or black widow spiders are prevalent, be sure to familiarize yourself with their appearance in order to distinguish them from less harmful spiders. Thankfully, most other spider bites can be managed with basic wound care.


I generally see scabies in the winter when people spend more time indoors and hats/heavier clothes are warn. Scabies are mites that  burrow into the skin, transferred from human to human. The skin manifestations of scabies are rough and scaly like a rash. Often, linear burrows can be seen where the mites have tunneled. Scabies have a predisposition for the web spaces between the fingers, but no area of the skin is off limits. For more information on scabies see my past blog.


For most insect bites, time is the best medicine. Try to avoid scratching, as this can cause scarring and introduce infection. Antihistamines can help block the body's response to the insect's saliva/venom.

Studies have shown, however, that antihistamines have a better effect when used proactively. For instance, if exposure is anticipated, an antihistamine (Claritin, Zyrtec, etc) can block the body response to bites, leading to smaller, less itchy bites. Insect repellent is also a good idea for proactive considerations.

Advice is different for scabies for which the insect has taken up residence in the skin. Scabicidal creams can eradicate the skin of scabies when used as directed. See my other blog for more complete treatment information. 

When treating spider bites, wound care is necessary depending on severity and geared at preventing a secondary infection while also promoting healing.

In Conclusion

Insects remind us each summer that our position atop the food chain may not be as secure as we commonly think. Bites are commonplace, some with obvious culprits and others that are more insidious. A basic knowledge about characteristics can better direct identification and treatment.

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