My Peterson Field Guide to Eastern Butterflies gives the Latin name of this butterfly as Pieris napi, and some sources consider P. oleracea to be a subspecies of P. napi, the Green-veined White.
Whatever the case may be ... this species is distinguished from the closely related Cabbage White (P. rapae) by the lack of black markings on the dorsal surfaces of the wings, and the strongly veined undersides of the hindwings. The veins are less pronounced in the summer incarnation of the butterfly.
And true to their names, it seems that Cabbage Whites do have a marked preference for cabbage, whereas the Mustard Whites stick to wild members of the family Brassicaceae (a.k.a. Cruciferae) – Differential selection of host plants by two Pieris species.
The next photo is the only keeper, one of several attempts to capture an image of my first encounter with a Henry's Elfin (Callophrys henrici) ... this small butterfly just wouldn't stop moving. Preferred larval host plants are huckleberries, blueberries, viburnum and plums.
