Dainty Sulphur (Nathalis iole) (Boisduval, 1836)

Diagnosis: This is the smallest (wingspan: 22 to 30 mm) sulphur found in Canada. The ground colour of the upperside is yellow, sometimes with orange on the hindwings. There are two distinct black bands on the upperside, one on the forewing lower margin and the other on the hindwing upper margin. On the underside of the forewings there are three submarginal spots.

Range: A widespread species of the southern U.S., the Dainty Sulphur is only irregularly reported as a migrant in Canada. There are six Ontario records, from Point Pelee in the south to Sault Ste. Marie in the north. In western Canada, it has most often been seen in southern Manitoba (eight records) and there is a single record from Saskatchewan at Round Lake.

Similar Species: The Little Yellow (Eurema lisa) lacks the black bars on the upperside of both wings. [compare images]

Early Stages: The small dark green larva has a purple dorsal stripe with a yellow or white side stripe. Although never recorded in Canada, larvae have been found in the northern states on a wide variety of plants that occur in weedy areas and in gardens, including marigolds and chickweed.

Abundance: The Dainty Sulphur is a very rare stray in Canada in migratory years.

Flight Season: In Manitoba it has been recorded from 25 July to 27 September. The Saskatchewan record was on 3 June, very early for this species.

Habits: The butterflies are normally found in open areas and along roadsides where their weedy foodplants grow. For such a small butterfly, it is strongly migratory, sometimes appearing in large numbers heading north in the U.S., usually along major river corridors (Pyle, 1981).

Remarks: There is some evidence that the Dainty Sulphur has bred for at least one generation in Manitoba, but it does not overwinter (Klassen et al., 1989).

© 2002. This material is reproduced with permission from The Butterflies of Canada by Ross A. Layberry, Peter W. Hall, and J. Donald Lafontaine. University of Toronto Press; 1998. Specimen photos courtesy of John T. Fowler.