Florida White (Appias drusilla)
Without close examination, it is difficult to distinguish the florida white from the great southern white (Ascia monuste), which is of similar size and color. The most noticeable difference is that the wings of the florida white are almost completely white (a small band of black may be present on the forewing and some very light shading on the underside of the wings, but to a much lesser degree than in the great southern white). Additionally, the wings, particularly the rear wing, are more angular.
I have seen these butterflies in meadows on partially wooded hillsides, feeding in mixed groups with the great southern white. The florida white seems to be considerably less common, although it is hard to prove as the species are so difficult to distinguish when on the wing.