This article originally appeared in the July 2004 Harvard Men's Health Watch and is provided courtesy of Harvard Health Publications.

Insect bites and stings

Summertime, and the stinging is easy. Insect bites are as much a part of summer as barbecues and ball games. Most bites are little more than a nuisance, producing a brief ouch and a mild itch. Even the mildest bite, though, can have major consequences if the insect happens to be a mosquito carrying an encephalitis virus or a tick carrying the critter that causes Lyme disease. Other bites can cause considerable pain and swelling — and a few can trigger life-threatening allergic reactions in sensitive individuals or major toxic reactions in anyone who gets enough venom.

Here is a rundown on some of the insects in your neighborhood.

Mosquitoes and ticks
These insects are harmless unless they are carrying infectious agents. Although mosquitoes and ticks are everywhere, the worrisome infections are concentrated in certain locales. Encephalitis viruses, such as the West Nile virus, can crop up in pockets anywhere in the country; your health department will issue an alert if one of them has appeared in your area.

Mosquitoes like stagnant water, and they like to bite at dusk and dawn. It’s always a good idea to eliminate standing water, but widespread spraying is not necessary unless you know encephalitis is in the community. Follow the general precautions (see “Don’t let ’em get you”) to help fend off mosquitoes and biting flies.

About 90% of the nation’s Lyme disease occurs in eight states from Massachusetts south to Maryland; outbreaks have been reported in Wisconsin, Minnesota, northern California, and Oregon. Other tickborne infections follow similar patterns. Ticks like the woods and nearby grass. If you venture out in a Lyme disease area between April and October, be sure to take the precautions that will help protect you against all bites (see below); long sleeves and pants are particularly important. And since tick bites are usually painless, be sure to inspect yourself — and your dog — when you get home. It takes many hours to transmit Lyme disease, so you can prevent infection simply by removing the tick promptly with tweezers and then washing the bite with soap and water. Antibiotics, even a single 200-mg dose of doxycycline, can also prevent infections, but most experts don’t think medication is necessary.

Wasps, yellow jackets, hornets, and bees
You may be interested to know that only the female members of these closely related species have stingers. They are responsible for most of the insect-related deaths in the United States, about 40 a year, not because they are intrinsically toxic like some spiders (see below), but because some people are allergic to Hymenoptera venom. Yellow jackets are the most aggressive; they nest in the ground and tend to set up shop in areas of human activity. Hornets and wasps nest off the ground, often away from people. Most honey bees are actually quite docile unless provoked, but the Africanized bees (“killer bees”) that are spreading from Mexico north into the United States are much more aggressive, though their venom is not any more potent.

The general precautions outlined below should help protect you from bees, hornets, wasps, and yellow jackets. Be particularly careful to avoid the brightly colored garments, floral patterns, and sweet scents that attract these bugs. If a bee breaks through your line of defense, remove the stinger promptly by scraping it away with a sharp-edged object such as a credit card (see figure below); other methods of removal may release additional venom. These stings are painful; treat them by applying a cold pack and, if needed, taking a mild pain reliever, such as aspirin, ibuprofen (Advil and other brands), or acetaminophen (Tylenol and other brands).

Aside from pain, most of these stings are harmless. But people who have allergies can develop large areas of swelling around the area. Ice packs can help, as can antihistamines such as diphenhydramine (Benadryl).

The most serious allergic reaction is anaphylaxis, which can be lethal. Hoarseness, wheezing, a swelling of the mouth and throat, abdominal cramps, a racing pulse, and lightheadedness are signals that collapse and even death may follow. It’s a medical emergency and requires immediate attention. People who have had previous allergic reactions must do everything possible to avoid stings. They should also wear medical alert bracelets and carry bee sting kits so they can treat themselves with an injection of epinephrine (adrenaline) and an antihistamine tablet. Venom immunotherapy, administered in a series of shots by an allergist, can protect most highly allergic people against disaster. It may require an injection a month for five years or more, but it ’s well worth the effort.

Removing a stinger To remove the stinger left by wasps, bees, and similar insects, take a sharp-edged object (like a credit card) and swiftly scrape the stinger from the skin.

Spiders
Although all 60 species of North American spiders that bite people have venom, only two are highly toxic. The black widow spider is well named: Only the female is large enough to be dangerous. It has a small head, a shiny round abdomen, an orange hourglass on its body, and long spindly legs. Despite its name, the black widow may be brown or tan. Its web is coarse and irregular and often turns up in garages, basements, or woodpiles.

A black widow bite is sharp but only mildly painful. The trouble begins 30 minutes to 12 hours later, with severe muscle cramps that are usually most intense in the abdomen, thighs, and back. Larger doses of venom also produce widespread swelling, labored breathing, and convulsions. Urgent medical treatment is critical; fortunately, nearly all victims recover fully. An antivenom is available but is rarely used.

The brown recluse spider is also well named; the insect is secretive and may even take refuge in clothing that is piled on the floor. Because its appearance is not distinctive, it is often mistaken for other spiders and is ignored.

A brown recluse bite produces little or no pain. In just a few hours, though, the site becomes red and swollen, often with blisters. In a day or two, the area may enlarge and turn black. A few victims develop general reactions that may be severe, but most recover slowly with local wound care. An antivenom is available, but it’s not helpful if it’s used more than 24 hours after the bite. If the bite becomes infected, antibiotics are necessary.

Don’t let ’em get you
Although most bites are mild and harmless, try to avoid insect bites as much as possible.

Clean out spider webs, and stay away from spiders that are crawling near you. When you are in an area with lots of ticks, wear shoes and long sleeves and pants; button your cuffs and tuck your pant legs into your socks. Light-colored garments will give you the best shot at spotting ticks. Avoid bright colors, floral patterns, and sweet scents that attract bees. Stay behind screens between dusk and dawn, when mosquitoes rule.

Use insect repellents. Products containing DEET are best for mosquitoes, ticks, flies, and fleas. Preparations with 10%–30% DEET are safe and effective for adults. Protection lasts for several hours, but it diminishes with swimming and heavy perspiration. For extra protection against ticks, you can spray permethrin (PermaKill and other brands) on your clothing; a single application will last for up to a week.

Have a nice summer.