Economic entomology for the farmer Economic entomology for the farmer and fruit-grower [microform] : and for use as a text-book in agricultural schools and colleges economicentomolo00insmit Year: 1896 :86 AN ECONOMIC ENTOMOLOGY. the little fellows everywhere, infesting almost all kinds of insects, and undoubtedly they do much to prevent the increase of injuri- ous species. Especially is this true of those ovipositing in eggs of other forms, for they are then 'nipped in the bud,' so to speak. Their work in the destruction of scale insects is also of great importance, and frequently we find on
Economic entomology for the farmer Economic entomology for the farmer and fruit-grower [microform] : and for use as a text-book in agricultural schools and colleges economicentomolo00insmit Year: 1896 :86 AN ECONOMIC ENTOMOLOGY. the little fellows everywhere, infesting almost all kinds of insects, and undoubtedly they do much to prevent the increase of injuri- ous species. Especially is this true of those ovipositing in eggs of other forms, for they are then 'nipped in the bud,' so to speak. Their work in the destruction of scale insects is also of great importance, and frequently we find on a scale-infested tree a large proportion with little round holes, showing where a para- FiG. 445. Fig. 444, Trichogramma pretiosa, a parasite in insect eggs ; a dot may represent natural size. Female Isosoma oviposit- ing in stem of wheat. site has emerged. It is a pity that in a family so generally useful we should find, exceptionally, some injurious species ; but there is no doubt that members of the genus Isosoma lay their eggs in the stems of grasses, including wheat, and the larvae, working as they do in the joints, have received the name 'joint-worms.' The stem hardens where the larva punctures it, and this inter- feres with the nourishment of the plant above that point, les- sening or entirely preventing the formation or maturing of the grain. There is but a single annual brood of these insects, and the winter is passed in the straw, from which the adults emerge in spring. In localities w^here this insect is sufficientlv abundant to make it necessary to use remedial measures, the utilization of
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