Final answer:
Millipedes do not sting, but they can secrete irritating chemicals that cause skin irritation, redness, and swelling. Washing the area with soap and water usually helps, but medical attention should be sought if symptoms persist or worsen.
Step-by-step explanation:
To recognize a millipede sting, one should first be aware that millipedes do not actually sting, but they can secrete a defensive fluid that may cause irritation if it comes into contact with skin. Signs of a reaction to millipede secretions include skin irritation, redness, swelling, and in rare cases, small blisters. These secretions contain chemicals like hydrochloric acid and can sometimes cause a mild to moderate burning sensation. It is important to wash the affected area with soap and water to remove any remaining chemicals. If the irritation persists or if allergic symptoms develop, it is advisable to seek medical attention.