Economic entomology for the farmer Economic entomology for the farmer and fruit-grower economicentomolo01smit Year: 1906 I30 AN ECONOMIC ENTOMOLOGY. been introduced, and, after a long series of experiments with insecticides, none of which proved satisfactory, resort was finally- had to American stocks upon which the foreign varieties were grafted. This has proved effectual to an extent ; but it seems that, in the course of time, the period varying somewhat, even American stocks lose ^'^- 95- their exemption in Europe and become gradually subject to injury from the Phyl- loxera attacks. We hav
Economic entomology for the farmer Economic entomology for the farmer and fruit-grower economicentomolo01smit Year: 1906 I30 AN ECONOMIC ENTOMOLOGY. been introduced, and, after a long series of experiments with insecticides, none of which proved satisfactory, resort was finally- had to American stocks upon which the foreign varieties were grafted. This has proved effectual to an extent ; but it seems that, in the course of time, the period varying somewhat, even American stocks lose ^'^- 95- their exemption in Europe and become gradually subject to injury from the Phyl- loxera attacks. We have a number of species of this same genus infesting a great variety of plants not of economic interest. Perhaps the most com- mon is that which forms large, blister- like galls on hickory leaves, so prominent as to attract attention from even the most casual observer. If one of these galls be cut open, the inside will be found lined with numerous minute, yellow insects, with dusky wings which lie folded flat over the back, and in this par- ticular the Phylloxera differs from the typical aphids, which have the wings vertical when at rest. The subject of dealing with underground pests, or plant-lice which feed upon roots, is one of importance, upon which the last word has not yet been said. As against the Phylloxera, bisulphide of carbon has proved useful, injected by means of a proper instrument into the ground at about the level of the roots and allowed to permeate the soil. The fumes are deadly to insects, and where they reach them in any but the ^^^ stage, kill. The Phylloxera does not require attention in our country at the present time, and no large space need be given the subject of remedies against it. The matter is different when we consider the species which infest other cultivated plants ; whether Rhizo- Galls of Phylloxera on grape-leaf.
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