. The natural history of the farm; a guide to the practical study of the sources of our living in wild nature. Natural history. SOME INSECTS AT WORK ON FARM CROPS 271 Pig. 113. An aphid skin with a hole in its back, whence has emerged a para- site. to our shores along with imports of plant materials of various sorts. They have become established in our fields; but fortunately they attack only a few of our plants that are closely related to their own native food-plants. Pests like the brown-tail moth, having an unusually wide range of diet (including in this example the leaves of most of our de
. The natural history of the farm; a guide to the practical study of the sources of our living in wild nature. Natural history. SOME INSECTS AT WORK ON FARM CROPS 271 Pig. 113. An aphid skin with a hole in its back, whence has emerged a para- site. to our shores along with imports of plant materials of various sorts. They have become established in our fields; but fortunately they attack only a few of our plants that are closely related to their own native food-plants. Pests like the brown-tail moth, having an unusually wide range of diet (including in this example the leaves of most of our deciduous trees), are unusually difficult to control. Under natural conditions, there is an occa- sional excessive increase of foraging insects. Hordes of them suddenly appear, and destroy the foliage of one or two species of plants. For this evil, nature has her own methods of control. She uses carnivores and parasites to keep each species in check. In the midst of the aphid colony on a cabbage leaf, or on the curled tip of an aphid-infested apple spray, one may often see both predatory and parasitic foes of the aphids work- ing side by side to keep down the colony. Ladybird beetles and their larvae (fig. iii) consume the aphids bodily. Lacewing fly lar- vae (fig. 112) and. Fig. 114. A parasitized moth larva on a blue-grass top: some of its parasites have spun their cocoons beside it. others, on the grass-blade above. 6, shows an easy method of hatching out the adult parasites from the cocoons. (From the author's "General Biology").. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Needham, James G. (James George), 1868-1956. Ithaca, N. Y. , The Comstock Publishing Company
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectnaturalhistory, booky
