The insects responsible for allergic reactions are almost exclusively in the class Hymenoptera. The most important are yellow jackets, hornets, wasps, honeybees, and fire ants. Allergy to insects may affect individuals who are either allergic (atopic) or non-allergic to common pollens and molds. Reactions may be local and are characterized by swelling, redness, and pain, or they may be systemic. Examples of systemic reactions are: generalized urticaria (hives); bronchospasm (asthma-like symptoms); throat swelling; and in some patients, low blood pressure. Severe systemic (anaphylactic) reactions may be fatal if not treated promptly. Anaphylactic reactions are mediated by allergic antibodies directed against components of the insect venom. Following the sting and penetration of the venom, the venom antigens react with the allergic antibodies present on the surface of mast cells and basophils. These antigen-antibody reactions initiate a series of intracellular events that culminate in the release of several active chemicals such as histamine. The action of these compounds on the various tissues is responsible for the symptoms of allergy in a person. The presence of significant amounts of allergic antibodies directed against insect venom can be demonstrated in an individual by skin tests or by a laboratory test, using the individual’s serum; the test is known as a radioallergosorbent (RAST) test. See RAST. In recent years the treatment of highly allergic patients has been improved significantly with the introduction of better allergenic materials for diagnosing and treating insect allergy. Today, it is recommended that patients with a clinical history of severe anaphylactic reactions to insect venom, and high levels of allergic antibodies, be treated by immunotherapy, starting with small doses of venom extract and increasing the dosage. Following are the main characteristics of insects that cause allergic reactions: Yellow Jackets Bands of yellow and black around the thorax and abdomen. The head is yellow and black. Yellow jackets are second only to hornets in aggressiveness and are frequently seen near garbage and picnic areas. Their nests are large and are usually
located in the ground, often in tall grass between the walls of buildings or under stones.
Hornets Black body with white markings on the thorax and abdomen. The face, excluding the top of the head, is also white. Hornets may be difficult to distinguish from yellow jackets, since they often have yellow markings. Hornets’ nests are large, gray, or brown and are located in tree branches, under the eaves of houses, or against a wall, usually more than four feet above the ground. Hornets are considered the most aggressive of the major stinging insects, sometimes attacking without apparent provocation.
Wasps Black or brown with yellow or white stripes and a fusiform (tapering toward each end) abdomen. The wasp can be distinguished from the yellow jacket and the hornet by its thin waist, which joins the abdomen and the thorax. Wasps are not as excitable as the other stinging insects; they usually sting only if touched or brushed while in flight around the nest. They build their nests in trees or around shelters such as the eaves of houses or porches. The nest is usually small and contains thirty to sixty insects.
Honeybees Easily recognized by their small, stocky, brown, yellow, or black bodies with a round abdomen. Probably the best-known insect, honeybees are found most frequently in artificial hives, but the colonies may be found in natural nests inside the trunks of trees, under floorboards, and in other enclosed areas. The stinger differs from that of the yellow jacket, wasp, or hornet, in that it cannot be used repeatedly (the stinging apparatus is severed from the body after the sting, the stinger is left in the skin, and the bee dies).
Fire Ants Introduced from South America during the 1920s, fire ants are now well established in several Southern states. The venom of the fire ant differs from that of hymenoptera insects, in that it can produce severe local reactions or systemic anaphylactic reactions. The insect attacks by biting to secure itself, then inserts its stinging apparatus, which contains the venom. Highly sensitive patients with high levels of allergic antibodies against the venom of the fire ant are usually treated with immunotherapy. Someone who is sensitive to insect bites should avoid : 1. Standing in the direct path of a flight of insects 2. Contact with a nest 3. Throwing objects at a nest 4. Mowing the lawn 5. Planting flowers 6. Trimming hedges or shrubs 7. Painting houses 8. Handling trash or garbage cans 9. Walking barefoot outdoors 10. Cooking or eating outdoors 11. Using scented preparations such as perfume, hairsprays, colognes, or deodorants 12. Wearing brightly colored clothing with flower patterns