Caterpillars make tasty treats for birds and other wildlife, so many developed a deterrent: stinging spines. Just because a caterpillar looks soft and fluffy doesn't mean you should try to pet it -- those are the ones most likely to sting. These stings can be as painful as those of a bee (or more so in some cases) and might require immediate medical care for those sensitive to the stinging chemicals.
Avoiding the Sting
When you see an innocuous-looking fuzzy caterpillar just begging to be picked up, avoid the temptation. He might look soft and cute, but it's sometimes difficult to tell the stinging caterpillars from the safe ones. It's best to leave them alone rather than touch them with bare hands. Caterpillars sometimes hide on the underside of leaves as they eat, which means you might get stung by accident while you work in the garden. Wearing gardening gloves as you work can help prevent the stings, and always use gloves when you must relocate a fuzzy or spiny caterpillar.
It's Good to Be Spineless
You'll likely know right away when you've been stung -- it starts to burn and itch almost immediately. Grab some clear tape and press it over the sting, removing it to remove spines that might be stuck in or lying on your skin. Don't try to brush them off with your other hand; you're likely to get stung again. You might need to use several pieces of tape to remove all the spines, but it's essential to get them all off your skin. They can continue to sting even after they're no longer attached to the caterpillar.
Take a Chill
Icing the area as soon as possible helps relieve the pain. It also helps prevent any swelling, and you should apply it right away, before the swelling appears. After you've chilled the area for a few minutes, make a paste of baking soda and water and spread it over the sting to help with the pain. Follow up with more ice as necessary.
Help the Itch
If the stung area continues to itch and burn slightly, taking an over-the-counter oral antihistamine can help. You might also find some relief by rubbing a topical antihistamine over the area. However, if the itching spreads to other areas of your body or if you have trouble breathing, seek immediate medical attention; some people are highly allergic to caterpillar stings and require prompt care from a doctor.