Bees and ants usually are looking for food, not trouble. But cross their paths, or their nests, and you could feel their sting. About 40 people in the United States die from allergic reactions to insect venom each year. After you have been stung once, you can become allergic to that insect's venom. The insects that are most likely to provoke dangerous allergy reactions are classified in the order Hymenoptera — bees, wasps, hornets, yellow jackets and fire ants. Biting flies, ticks, mosquitoes and spiders also can cause allergic reactions, though they tend to be milder.

A sting is never pleasant. Without allergy, a typical reaction is burning pain, redness, swelling and itching on the skin in the area of the sting.

In an allergic reaction, symptoms are not limited to the area that is local to your sting. A mild allergic reaction may cause symptoms that mimic hay fever, or may produce a rash of puffy pink "hives" or "welts" on parts of the skin that are not near to the sting. Symptoms of a mild allergic reaction could include runny nose, tearing or itching of the eyes, sneezing, or a metallic taste in your mouth.

Technically, every allergic reaction that occurs within minutes of exposure is a form of anaphylaxis, but doctors commonly reserve this term to refer to severe allergic reactions. A severe allergic reaction (anaphylaxis) can cause any of the symptoms of mild allergy (such as hives or hay fever symptoms); in addition, it can result in rapid swelling of your lips or throat, swelling around the eyes, throat tightness, wheezing, difficulty breathing, hoarseness, nausea, vomiting, diarrhea, abdominal pain, lightheadedness, or passing out due to low blood pressure.

Most insect-sting allergies are to bees, hornets, wasps and yellow jackets. Fire ants are present in the southeastern United States and can also cause allergic reactions when they sting.

Honeybees, the most common of these stinging insects, aren't aggressive unless provoked. You can recognize them easily by their hairy bodies and bright yellow or black markings. They typically are found around flowers or clover. Once they sting, they die. They often leave their stinger behind.

Yellow jackets are the most aggressive of the stinging insects. Less chunky than bees and bright yellow with black markings, they hover around garbage and wherever there are exposed foods, particularly those containing sugar. They may sting repeatedly. They nest in the ground.

Hornets have short black bodies with yellow or white markings. They nest in trees or bushes and may sting repeatedly.

Wasps are hairless with narrow "waists" that separate their chests from their long, slim, lower bodies. They can be black, brown or red. Wasps build nests under the eaves of buildings and under rafters. They sting repeatedly.

Fire ants inhabit the southeastern United States and attack people who walk on their nests. Their stings cause intense burning. A fire ant may bite into the skin and, while its head and jaw are locked in one place, quickly walk its abdomen and rear stinger in a wide arc, stinging repeatedly in a circle. Alternatively, it may leave a stripe of stings in its path as it runs across your leg.

Of course, the best way to avoid an allergic reaction to insect venom is to avoid getting stung. Here's how:

Keep your distance
Stay away from areas where insects congregate, including gardens and hedges, around fruit trees, and near garbage cans. When dining outdoors, keep food covered until you're ready to eat, and clean up afterward. Garage and patio areas should be kept clean and free of debris, and garbage cans should be tightly sealed. If you encounter the insects, slowly back away. Don't swat at them, flail your arms or make sudden movements that could trigger an attack.

Dress for success
Bees, hornets and other flying insects are attracted to bright colors and floral patterns. During picnic season, dress in white, khaki and other light solids, covering as much of your body as possible during late summer and early fall when insect numbers are at their peak. And avoid loose-fitting clothing, as insects can become trapped in it.

Insects also are attracted to smells, so avoid wearing perfume, colognes or other fragrances, including suntan lotion, cosmetics, hair spray and scented deodorant. Outside, wear closed-tow shoes rather than sandals.

Check your car before you drive
If you leave your car's windows open, check before getting in to make sure there are no flying insects inside. Running the air conditioner with the windows closed while driving can help prevent on-the-road stings. Also, keep a can of insecticide in the car with you.

Advertise if you're allergic
If you know you are allergic to insect venom, wear a MedicAlert or other type of medical identification. To order MedicAlert identification, call 800-ID-ALERT. Many people with insect-venom or food allergies carry a small kit containing a syringe of epinephrine (adrenaline) to inject if they begin to develop signs of an anaphylactic reaction.

Scrape out the stinger
If you get stung by a honeybee, scrape out the stinger with a credit card or a long fingernail. If you try to pull it out, you'll squeeze the venom sac and accidentally release more venom. Scraping it out leaves the venom sac undisturbed.

To ease the pain of a sting, take a pain reliever such as acetaminophen, ibuprofen or aspirin. Children should never be given aspirin because of the risk of Reye's syndrome, a rare, but life-threatening illness. Some people make a paste of water and meat tenderizer and apply it directly to the bite, but this treatment isn't recommended. This home remedy has been tested in small studies, and it doesn't reduce symptoms.

Get your shots
Once you've had a severe reaction to a stinging insect, you have about a 60 percent chance of having another anaphylactic reaction if stung again.

You can reduce your risk with immunotherapy, also called "desensitization" or "allergy shots", in which you get injections of diluted venom from the same insect that causes your allergic reaction. The continuous, slight exposure from these injections stimulates your immune system to replace its allergic reaction to venom with a more subtle type of immune response that does not result in allergy symptoms. After the first year of immunotherapy, the treatment is effective at preventing a future allergic reaction for at least 70 percent of individuals. Immunotherapy must be continued for a minimum of three years and people who have had an anaphylaxis reaction that included throat swelling or low blood pressure are usually advised to continue immunotherapy indefinitely.

Venom immunotherapy is recommended for adults or children who have had severe allergy symptoms after a sting. Skin tests are used to identify or confirm the insect type that triggered the allergy.