Megalopyge opercularis. Also known as the hag caterpillar. If you see this, retreat! Fiance' laid his arm on patio chair not noticing it on the arm. This thing is covered with poisonous hairs and is incredibly painful. He began to feel ill and dizzy so we ended up at hospital which gave him an antihistamine and pain meds. Iif you do come in contact, use a credit card to scrape out the hairs asap! There are 3-4 other poisonous caterpillars. of the same type.