Female coloration stretches between bright yellow (like the solid state of sulphur) to greenish-white. Males are a rich, buttery yellow. Both have a double white spot on the forewing, though in males it is usually rimmed with a dark border so it is more visually pronounced. They are very similar in appearance to Orange sulphurs (also in the Colias genus) and can may be mistaken for them in the field. They fly direct routes to their destination, but it may look like they are sloppy in flight. Their front pair of legs are the same length as the others, whereas other families of butterflies have very short front legs. These long legs allow it to comfortably walk.
Caterpillars are chubby and green with a black stripe along the body. They especially enjoy feeding on clover, but they will also eat the leaves of alfalfa and other bean plants.