Cochineal - Dactylopius coccus
Seen in cactus of the genus Opuntia. Apparently these scale insects live and feed on the cacti. They produce carminic acid to deter predators. This substance is used as colorant, dating as far back as the 15th century, according to Wikipedia.
The cochineal is a scale insect in the suborder Sternorrhyncha, from which the natural dye carmine is derived. A primarily sessile parasite native to tropical and subtropical South America through North America , this insect lives on cacti in the genus ''Opuntia'', feeding on plant moisture and nutrients. The insects are found on the pads of prickly pear cacti, collected by brushing them off the plants, and dried.