This is often the last butterfly of the year that I see, sometimes here in Ohio as late as mid-November. I also come across them pretty consistently on my visits to southern Illinois in October.
The Clouded Sulphur may be encountered in fields, lawns, alfalfa or clover fields, meadows and roadsides. Swarms of these butterflies often congregate at mud puddles. Their range covers most of North America.
Unlike some other late-flying species, the Clouded Sulphur does not hibernate over the winter as an adult. On the upper sides of its wings, males have a solid black border, while the females have yellow spots in their borders (unfortunately, this butterfly rarely lands with its wings open).
The word “butterfly” probably originated because of the yellow color of European sulphurs. The Clouded Sulphur has seasonal color variations that range from a white to yellow.
To me seeing this insect is a sure sign of Autumn, as it often visits Fall-flowering plants like New England Aster.