It may be one of the Hemaris clearwings: http://www.npsc.nbs.gov/resource/distr/lepid/moths/vt/1481.htm http://www.npsc.nbs.gov/resource/distr/lepid/moths/vt/1480.htm or any of a set of similar hawkmoths without clearwings. Pretty cool insects. Mark Walker Castleton, VT