A chemically identical dye derived from the woad plant "(Isatis tinctoria)" was used instead. The genus includes woad ("Isatis tinctoria"). They suggest that the source of the dye was indigo or "Isatis tinctoria". Woad ("Isatis tinctoria") was important as a source of indigo blue textile dye. The larvae feed on "Isatis tinctoria", "Raphanus raphanistrum" and "Eruca vesicaria". Instead, Karaites propose that the source of the dye was indigo or woad ("Isatis tinctoria").