Nathalis iole, the dainty sulphur or dwarf yellow, is a North American butterfly in the family Pieridae.

Some feel that the dainty sulphur is so unique among pierids, in shape and in several structural features, that it should belong in a separate subfamily.

Male dainty sulphurs have an oval scent patch (called an androconial spot) in each hindwing bar.

The barred yellow is larger than the dainty sulphur, and the underside of the wings is either all grayish white or brownish red.

The species lives in almost any open space including coastal flats, deserts, fields, roadsides, vacant lots and waste areas.

Females lay their lemon-yellow or orange-yellow eggs singly on young or emerging leaves of the host plant.