An insect which feeds on the Oactus opuntia, or prickly pear of Mexico and other parts of South America. In the dried state in which it is brought to Europe it resembles grains about one-eighth of an inch long, with one side round and transversely wrinkled, and the other rather flat. The colour is of a purplish grey; the grey is owing to a powder which covers it naturally; the purple tinge proceeds from the colour extracted by the water in which it has been killed. The rich crimson colouring matter which it yields does not appear to be injured by long keeping in a dry place, some cochineal of 130 years' old having been found to produce the same effects as new. The colouring matter may be extracted either by water or alcohol. Alum was formerly the only substance used to fix the dye of cochineal. About the year 1650, Drebdel, a German chemist, discovered the effect of tin in heightening the colour. The solution of tin in different acids will produce crimson, purple, violet, and scarlet of various kinds.