It is a Lophocampa maculata - Spotted Tussock Moth.
The following quote is from Wikipedia:
"The Spotted Tussock Moth, Mottled Tiger or Spotted Halisidota (Lophocampa maculata) is a moth of the Arctiidae family. It is found across southern Canada, the western parts of the United States, south in Appalachians to South Carolina and Kentucky.
The wingspan is 35–45 mm. The moth flies from May to July; the larvae remain from July to September. There is one generation per year.
The larvae feed on the leaves of poplar and willow, but also feed on alder, basswood, birch, maple and oak.
Named "Tussock moth" for the tufts of hair on the caterpillar."
