The last observed of c. two-dozen larvae; and the only  one 
collected and brought indoors (11-September) where it fed on  
Northern Prickly Ash for only two more days before pupating.
Unlike other  late-instar larvae seen, appearing to be smaller, 
this one apparently  skipped the larger last instar, yielding 
this small "Spring form"  adult.  Forewing length, only 47mm.
Room kept at 62F.  Light from  east & south windows.
Eclosion, 26-Feb-2013.
                                                        D J Hoag, Grand 
Isle, VT