White wooly tufted caterpillar
It looks like a flannel moth caterpillar http://www.butterfly-fun-facts.com/stings/flannelmoth815cat6/ or possibly a yellow bear caterpillar. http://cfox.livejournal.com/91618.html Both can be extremely variable in coloration.
You might take a look at this site. http://www.discoverlife.org/mp/20q?guide=Caterpillars It is hard to id it from one photo. Another consideration is its size. Many caterpillars have features that vary as they grow, that is, newly emerged caterpillars look quite different from later instars. vw