The moth, Prodenia eridania1, belongs to the family Noctuidae. Its larva is known as the “Southern Army-worm,” and like many others of its family is of considerable economic importance as it feeds on many succulent truck and ornamental plants, chiefly in the Gulf States. Since it is easily reared and is representative of such a large group of economically important Lepidopterous insects, it is being increasingly used for physiological and toxicological research in the government laboratories.