More Swallowtails

One would have to call it a record shot - it was flying and not awfully close so I was pleased to have anything. 
When is a Swalltail common here? When ti is a Scarce Swallowtail.
When is a Swallowtail scarce here? When is a Common Swallowtail 
A good riddle and today was the first time I'd seen a Common Swallowtail here.
Today it was off to St. Melany with DS#1 and Chasrlotte A for a meal and a jolly good one we had too in a pretty rustic setting. 
Sort of thing the French do much better than the English.