Cocoons are white, yellow, light green and fleshy red. Yellow cocoon contains pigments of various carotene derivatives, and is also the pigment of yellow orange, pink, brown gray and other colors of cocoon. Some pigments in green cocoons are related to flavonoids, while others are related to chlorophyll, especially in wild cocoons. White cocoons are mostly used in production. White cocoon color, normal luster and uniform cocoon shape are important standards for high quality cocoons.