Are wasps harmful to humans?

Wasps can be harmful to humans because they can sting and cause pain, allergic reactions, and in rare cases life threatening anaphylaxis, though most wasp stings cause only local pain and swelling and are not medically serious for most people, and wasps also provide ecological benefits. Harm from wasps includes painful sting injecting venom that causes sharp pain, redness, swelling, and itching lasting hours to days, and for people allergic to wasp venom, sting can cause severe allergic reaction with difficulty breathing, swelling of face and throat, hives, dizziness, and drop in blood pressure requiring emergency treatment with epinephrine. Multiple stings increase venom load and risk of severe reaction. Social wasps like yellow jackets defend nests vigorously and can sting repeatedly, increasing harm if nest disturbed. However, wasps are also beneficial as they prey on pest insects like caterpillars and flies, providing natural pest control, and some pollinate plants. So wasps are harmful in sense that they can sting and cause allergic reactions, but they are not harmful in sense of seeking out humans to attack, they sting defensively. To reduce harm, keep food and sweet drinks covered outdoors, seal trash cans, avoid swatting wasps, do not disturb nests, wear shoes outdoors, and if nest near home poses danger, contact professional pest control for safe removal, and people with known allergy should carry epinephrine auto injector.