I read their larvae have venomous spines that can cause a painful sting and inflammation lasting for several days. In some cases, the sting may cause headache, nausea, and shock-like symptoms. Also urticaria. Not exactly this one, but the Megalopygidae family.
Found in extreme south Texas to Colombia.
I found this in http://bugguide.net/node/view/158848 Explanation of Names: virgo - Latin for virgin, a reference to the all white adult.