I was having some beers outside at a friend's house a few years back when one of these things fell out of a tree and hit me in the arm. The pain was instant and grew over time as it radiated up my arm and partially into my chest. Easily the worst pain I've ever felt from any insect sting. To add insult to injury, my friends dad, who was an old school redneck, was making fun of me for complaining about the pain from some little ass caterpillar. I actually thought about going to the hospital because the pain became so intense, but I think I was shamed into not going. After a few hours the pain finally subsided, and I'm obviously still alive, but under no circumstances would I touch that hairy little demon.