On what type of cactus does the cochineal insect feed?

It's on the cactuses of the Opuntia spp that the cochineal insect [Dactylopius coccus] feeds. It particularly favors Opuntia fica-indica, whose common name is barbary or Indian fig cactus. The insect keeps competitors from feeding on prickly pear moisture and nutrients by making carminic acid. The acid may be taken out of the insect's body and eggs, for the making of carmine or cochineal dye.