CACTEÆ. This plant is nearly allied to the prickly pear, and assumes a somewhat tree-like form. The insect as well as the cactus are natives of Mexico and other warm parts of America, but they are now cultivated chiefly in Guatemala. This cultivation was carried on by the Mexicans long before the country was known to Europeans. The insect is not uncommon on wild cacti in Texas and Florida. Both plant and insect have been successfully introduced into the Canary Islands, Algeria, Java, and Australia. But the attempt to produce cochineal in India has been practically a failure.
The cochineal insect is a small creature, a pound of cochineal being calculated to contain 70,000 in a dried state. The male is of a deep-red colour, and has white wings. The female, which is wingless, is of a deep-brown colour, covered with a white waxy powder; flat beneath, convex above.
In some parts of Guatemala large plantations of Nopal exist for the cultivation of the C. cacti. Before the rainy season commences, branches of this cactus plant covered with these insects are cut off and stored in buildings to protect them from the weather. When the wet season is over, four or five months afterwards (October), the plantations are again stocked from these supplies. Little 'nests' of some vegetable fibre, each containing about a dozen females, are placed on the spines of the cacti. The eggs are soon deposited, and when the young females are developed, they spread over the plants, attaching themselves to the leaves, and looking more like vegetable excrescences than insects. They become covered with a cottony substance. The first crop of pregnant females, only these being valuable for cochineal, is gathered in December, and several more crops are obtained till the following May.
In the Canary Islands the insects are reared in winter and put out on the cactus leaves from May to July. Small gauze bags containing pregnant females are hung on the cactus plants, from which the young when developed spread over the leaves. In August and September, just before the females are ready to deposit their eggs, they are collected in trays, and those gathered in one day are placed in the evening in an oven heated to 150° F. They are afterwards more thoroughly dried in the sun. Hot iron and boiling water are also used in killing the insects. According to the way the insect is killed and dried, the cochineal is known in commerce as silver or black; an inferior kind being sometimes called foxy. The colouring principle of cochineal is called cochinealin or carminic acid, and the insects scarcely yield more than 10 per cent. of pure dye, although the amount is generally supposed to be much greater. Carmine has also been demonstrated in other kinds of coccus and in aphides.
The cochineal industry has suffered very much through the introduction of aniline dyes. To see to what extent this is the case, it need only be stated that the amount of cochineal exported from the Canary Islands, where it is produced in by far the largest quantity, amounted in 1869 to 6,310,600 lb., which was valued at £842,921, while in 1885-95 the annual export from these islands only reached about 1,500,000 lb., valued at £80,000. Meanwhile the price has fallen from eighteen or twenty shillings per lb. to about two shillings (1895).