Allow me to introduce you to Megalopyge Urens. It is common in Montevideo during the months of January, February, and March.
A 1936 edition of Revista Soc. Entomológ. Argentina describes an encounter:
“I’ve been grazed on the elbow by one of them and was unable to determine which hairs produced the sting. I felt a muscle pain and cramping that came in spasms and jerks at the base of the fingers followed by pain in the chest and back, a pulling at the back of the neck and in the nerve of each tooth at the side of the face. The pain lasted some ten hours, sufficiently strong to keep me awake. In Montevideo, mothers fear greatly this caterpillar because its showy display attracts children who pick them up and suffer from contact with the hairs that often bring on fevers. A remedy, that I haven’t experienced, usually involves mashing the caterpillar and mixing it with oil or alcohol and making a compress to lay on the affected part.”
The caterpillar creates a cocoon, from which emerges a large moth that I once saw resting against the kitchen window one night. The colors of both are glorious but probably stand as a warning to all to give it wide birth.