Like golden clouds in the summertime, the Sulphurs spatter the radiators of our cars and dance over the green fields in happy ecstasy. Not so ecstatic is the farmer who sees voracious green caterpillars eating up his alfalfa and clover. The butterflies are very variable in color with several seasonal forms. The springform is rather pale, but, if you add more orange to the wings, you have the Flavid Sulphur, common in summer. Another summer form has the orange replaced everywhere by lemon yellow. There are several similar appearing Sulphur butterflies, but 3 characteristics in combination usually distinguish the Orange Sulphurs from all others. First, there is a dark diffusion at the base of each wing; second, there are usually 4 or more black dots on the undersides of the wings; and, third, the wings have no pink edges. Albinic or white individuals are quite common.
When the Orange Sulphurs crowd damp places in a roadway with fluttering wings or swarm over the fields, they truly appear as flying bits of butter. Their flight gives an appearance of clustered confusion, but it is on their great numbers and camouflage that they rely on for protection. A Sulphur alighting on a sunflower or poppy seems to vanish into the golden blossom.
The slender green caterpillar feeds mainly on clover, alfalfa, and lupine. The small fat chrysalid pulses its slow life hidden in thick grass.