The orange sulphur (Colias eurytheme), also known as the alfalfa butterfly and in its larval stage as the alfalfa caterpillar, is a butterfly that belongs to the lowland group of clouded yellows and sulphurs. A very common North American butterfly, when the wings are open, it shows a bright yellow colouration with various amounts of scaling in light orange. When the wings are closed, the ventral side shows a yellowish-orange colour along with an indistinct row of tiny black spots by the margins and a double spot at the center of the wings. Males have a solid black border around the wings, while the females have yellow spots in its place.
