Page:Popular Science Monthly Volume 7.djvu/726

706 that it is controlled with comparative ease. The natural enemies of the species are encouraged by the intelligent cultivator, and poultry may be taught to feed upon it. Of over twoscore predaceous and parasitic species of its own class which I have enumerated, those herewith figured may be considered the most important. The only true parasite is a species of Tachina-fly (Lydella doryphoræ, Riley), somewhat resembling a house-fly, which fastens its eggs to the doryphora larva. From these eggs hatch maggots, which feed upon the fatty portions of the said larva, which, after entering the ground, succumbs to its enemy, and, instead of eventually giving forth a beetle, as it naturally should do, gives forth, instead, the Tachina-flies. A number of different lady-birds (Coccinellidæ), of which the convergent lady-bird is the most common, devour the eggs of the doryphora. Of true bugs the spined soldier-bug (Arma spinosa, Dallas) is the most effective, though several other rapacious species assist it, all of them piercing and sucking out the juices of their prey. Of artificial remedies there are various mechanical contrivances for knocking the insects off the haulm and catching them—some such even being worked by horsepower. The sun is, also, so hot in some of the Mississippi Valley States that the larvæ are roasted to death if shaken from the haulm on to the hot soil at mid-day. The remedy of all others, however, and the one universally employed, is Paris-green, which is used either in the form of a powder, or in that of a liquid, being combined in the former case with from twenty-five to thirty parts of some dilutent, as flour-middlings, plaster, etc., and in the latter with one tablespoonful of pure green stirred into an ordinary bucketful or about three gallons of water. Enormous quantities of the poison have thus been used in America, especially since it has proved a perfect remedy for the cotton-worm in the Southern States as well as for the potato-beetle in question. Cautiously and judiciously used it proves cheap and effective, and a large experience goes to show that no ill effects follow such use of it. There is a very closely-allied species, the Doryphora juncta of Germar, called the bogus Colorado potato-beetle, which, very naturally, has often been confounded with, and mistaken for, the genuine depredator. It differs, however, in the eggs being paler; in the larva being paler, and in having but one row of black dots on each side instead of two; and in the beetle having the second and third black lines of the elytra (counting from the outside) joined, instead of the third and fourth; in the punctures of said elytra being more regular and distinct, and in the legs having pale instead of dark tarsi, and a spot on the thighs. Singularly enough, this species, though it feeds and thrives on Solanum CarolinenseSolanum Carolinensis [sic], will not touch the cultivated potato, and is, therefore, perfectly harmless to man.

The English reader is more particularly interested in this insect, because of its possible introduction into Europe; and on the subject of its introduction I cannot do better than quote some passages from