This section is from "Scientific American Supplement Volumes 275, 286, 288, 299, 303, 312, 315, 324, 344 and 358". Also available from Amazon: Scientific American Reference Book.
Mr. Zimmerman spoke of the importance of all cultivators knowing so much of insects and their habits as to distinguish their friends from their enemies. When unchecked they increase in an immense ratio, and he mentioned as an instance that the green fly (Aphis) in five generations may become the parent of six thousand million descendants. It is necessary, then, to know what other insects are employed in holding them in check, by feeding on them. Some of our most formidable insects have been accidentally imported from Europe, such as the codling moth, asparagus beetle, cabbage butterfly, currant worm and borer, elm-tree beetle, hessian fly, etc.; but in nearly every instance these have come over without bringing their insect enemies with them, and in consequence they have spread more extensively here than in Europe. It was therefore urged that the Agricultural Department at Washington be requested to import, as far as practicable, such parasites as are positively known to prey on noxious insects. The cabbage fly eluded our keen custom-house officials in 1866, and has enjoyed free citizenship ever since. By accident, one of its insect enemies (a small black fly) was brought over with it, and is now doing excellent work by keeping the cabbage fly in check.
The codling moth, one of the most formidable fruit destroyers, may be reduced in number by the well-known paper bands; but a more efficient remedy is to shower them early in the season with Paris green, mixed in water at the rate of only one pound to one hundred gallons of water, with a forcing pump, soon after blossoming. After all the experiments made and repellents used for the plum curculio, the jarring method is found the most efficient and reliable, if properly performed. Various remedies for insects sometimes have the credit of doing the work, if used in those seasons when the insects happen to be few. With some insects, the use of oil is advantageous, as it always closes up their breathing holes and suffocates them. The oil should be mixed with milk, and then diluted as required, as the oil alone cannot be mixed with the water. As a general remedy, Paris green is the strongest that can be applied. A teaspoonful to a tablespoonful, in a barrel of water, is enough. Hot water is the best remedy for house plants. Place one hand over the soil, invert the pot, and plunge the foliage for a second only at a time in water heated to from 150° to 200°F, according to the plants; or apply with a fine rose. The yeast remedy has not proved successful in all cases.
Among beneficial insects, there are about one hundred species of lady bugs, and, so far as known, all are beneficial. Cultivators should know them. They destroy vast quantities of plant lice. The ground beetles are mostly cannibals, and should not be destroyed. The large black beetle, with coppery dots, makes short work with the Colorado potato beetles; and a bright green beetle will climb trees to get a meal of canker worms. Ichneumon flies are among our most useful insects. The much-abused dragon flies are perfectly harmless to us, but destroy many mosquitoes and flies.
Among insects that attack large fruits is the codling moth, to be destroyed by paper bands, or with Paris green showered in water. The round-headed apple-tree borer is to be cut out, and the eggs excluded with a sheet of tarred paper around the stem, and slightly sunk in the earth. For the oyster-shell bark louse, apply linseed oil. Paris green, in water, will kill the canker worm. Tobacco water does the work for plant lice. Peach-tree borers are excluded with tarred or felt paper, and cut out with a knife. Jar the grape flea beetle on an inverted umbrella early in the morning. Among small-fruit insects, the strawberry worms are readily destroyed with hellebore, an ounce to a gallon of warm water. The same remedy destroys the imported currant worm.