The Small White (Pieris rapae) can be confused with the Large White (Pieris brassicae) and the Southern Small White (Pieris mannii) (which does not occur in the US) but the black patch on the tip of the wing of the Large White spreads out to about half way down the wing margin whereas on the Southern Small White it spreads out a shorter distance and on the Small White this patch is only limited to the tip of the wing.

As with the Large Whites, Southern Small Whites and Green-veined Whites (Pieris napi), males have a single spot on the upperwing while females have two.

Conservatory Garden, Central Park, Manhattan, New York City, New York, USA, 2 November 2017