What is Allergy: Insect Sting?

Several insects belonging to the class Hymenoptera are capable of injecting venom into humans and animals. These insects include honeybees, bumble bees, hornets, wasps, yellow jackets, and fire ants. All of these insects are currently found in the United States as well as in most other land areas of the globe. Their venom, which they use to kill or paralyze other insects, is composed of proteins and other substances. It is proteins in the venom that cause allergic reactions in people. Not everyone is allergic to stinging insect venom. In people who are not allergic, the venom causes only redness, itching, and mild pain and swelling at the site of the bite. Cleaning the area and applying ice are enough to relieve the symptoms. Even people who are allergic to the venom usually have only mild symptoms, although the swelling may extend beyond the area right around the sting. People with allergy may have a more serious reaction, called an anaphylactic reaction.

Source: http://www.emedicinehealth.com