Over the past week, I have noticed a large number of moderate-sized, yellow butterflies in our Columbia yard, moving rapidly through the property. These are cloudless sulphur butterflies, common throughout the eastern half of the U.S.
The adults feed on a wide variety of flowering plants but females lay a single, pill-like egg on the leaves of cassias, a group of legumes. The egg hatches to yield a bright green or olive-colored caterpillar that harbors longitudinal stripes. After feasting on the host plant, the caterpillar spins its chrysalis which resembles a folded, dying leaf; of course, an adult eventually emerges from this camouflaged chamber.
Closely related to cabbage whites, cloudless sulphur butterflies produce several generations in the course of a summer and then drift southward as autumn approaches; the majority winter in South Florida or South Texas. The increased numbers that I observed this week likely represent the vanguard of that migration.
