Economic entomology for the farmer Economic entomology for the farmer and the fruit grower, and for use as a text-book in agricultural schools and colleges; economicentomol00smit Year: 1906 384 AN ECONOMIC ENTOMOLOGY. Most of these parasites have the disadvantage of not influ- encing in the least the amount of injury done by the host; they simply prevent it from changing to an adult. It often happens that spinning caterpillars even complete their cocoon, and in this we find the mass of parasitic cocoons instead of the Lepidopter- ous pupa. On the other hand, some of them complete their Fig. 4
Economic entomology for the farmer Economic entomology for the farmer and the fruit grower, and for use as a text-book in agricultural schools and colleges; economicentomol00smit Year: 1906 384 AN ECONOMIC ENTOMOLOGY. Most of these parasites have the disadvantage of not influ- encing in the least the amount of injury done by the host; they simply prevent it from changing to an adult. It often happens that spinning caterpillars even complete their cocoon, and in this we find the mass of parasitic cocoons instead of the Lepidopter- ous pupa. On the other hand, some of them complete their Fig. 442. Apcuiteles species.—Little mass of cocoons on leaf, replacing an infested larva; a single cocoon below, from which adult has issued ; much enlarged. development and kill the caterpillar before it is much more than half-grown. Many of these cocoon-forming species belong to the genus Microgaster, and they are typical of a very large series in the family. The plant-lice-infesting forms frequently belong to the genus Aphidius. As in the previous family, many of these insects have an external ovipositor. While the preceding series of parasites contain a very fair pro- portion of large species, the next family, Chalcididce^ contains
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