Moved from Moths.

Despite being found under an apple tree, this probably is NOT an apple sphinx (Sphinx gordius) because the coloring is wrong. However, it's correct for Fawn Sphinx (Sphinx kalmiae) based on images in Wagner, p.259. Location is correct.

here's a quote from Wagner regarding physical features:
"Beautiful blue- or yellow-green caterpillar with seven oblique, abdominal lines narrowly edged with black above and usually yellow below. Head boldly marked with black line that is inwardly bounded with yellow-green. Most individuals recognizable by blue horn that bears minute black spine. Spiracles orange. Each midabdominal proleg has shiny yellow band between black crescents"

"Occurence: Woodlands, forests, also commonly yards and nurseries from Manitoba to Newfoundland south to Northern Florida and Lousiana, becoming uncommon southward."

Yours can be none other.

Wagner, D.L. (2005). Caterpillars of Eastern North America.

try googleing sphinx bizland and go thru the caterpillers at that site. it has a state by state list, many sphinx cats horn turns down in last instar. id do it myslef but i am too darn tired today..my navy son is traveling and i cant sleep when he is traveling... soon his plane will land.