Georgical Essays Author:Alexander Hunter Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: ESSAY IV. On the Aphides. JL He Aphis or Blighter, as we now, for the first time, venture to call it, from its being the most general cause of what are ter... more »med blights in plants, forms a highly interesting tribe of insects. In point of number, the individuals of the several species composing it surpafs those of any other genus of this country . These insects live entirely on vegetables. The loftiest tree is no lefs liable to their attacks, than the most humble plant. They prefer the young shoots on account of their ten- dernefs, and on this principle often insinuate themselves into the rcry heart of the plant, and do irreparable mischief before they are discovered. But for the most part they besetthe foliage, and are .always foimd on the under side of the leaf, which they prefer, not only on account of its being the most tender, but as it affords them protection from the weather, and arious injuries to which they would otherwise be exposed. Sometimes the root is the object of their choice, which, from the nature of these insects, one would not £ priori expect; yet have I seen the roots of lettuces thickly beset by them, and the whole crop rendered sickly and of little value : but such instances are rare. They rarely also attach themselves to the bark of trees, like the Aphis salicis, which being one of our very largest species, and hence pofsefsing superior strength, is enabled to penetrate a substance harder than the leaves themselves. Reaumur, considering each A/ihis as bringing forth ninety young, calculates that in five generations the produce from a single one would be five thousand nine hundred and four millions nine hundred thousand. As among Caterpillars we find some that are constantly and unalterably attached to one or more particular species of plants, an...« less