On our Butterfield Pond Hike in Giles State Forest, Wilmot, NH. See bugguide.net/node/view/434 for more information. Do not touch these caterpillars because their hairs cause skin irritation. The prominent identifying feature of these caterpillars are the four tussocks on the back and the yellow color. The photo on the left (not mine) is of the moth that this caterpillar turns into. Click on the moth to see a big picture of it.