February, 2010

Dainty Sulphur

We have several species of butterflies that can be seen all year in our area, even in the winter. One of these is the miniscule dainty sulphur (Nathalis iole), the smallest sulphur in the U.S., and one of the smallest butterflies, with a wingspan of about an inch. As is common with butterflies that produce caterpillars and adults throughout the year, the cold-weather and warm-weather adults look different. During the summer, dainty sulphurs are rather light-colored and very yellowish. They almost always rest with their wings closed, so the underside is what one normally sees when getting a good look at this butterfly. Dainty sulphurs found in the winter are often a dull gray or greenish color, mainly on the lower surface of the hind wing. When it is really cold, these butterflies perch on the tip of a dead stick or piece of grass, fold their wings down very tightly, and look remarkably like a dry leaf.

Many of the flowers that bloom during Dec. to Feb. in our area are quite small, such as speedwell, oxalis, henbit, and other lawn weeds that survive cold weather by hugging the ground. This butterfly is certainly diminutive enough to take advantage of these nectar sources. The caterpillars of this species feed on plants in the sunflower family, including asters and various weeds and spring wildflowers.