The Canadian Entomologist, 1920, Vol. 52 (Classic Reprint)

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Excerpt from The Canadian Entomologist, 1920, Vol. 52BY E. H. Strickland, Entomological Branch, Dominion Dept. Of Agriculture.Cottonwoods and other poplars have proved to be the trees best adapted for shade and ornamental purposes on the treeless plains Of Southern Alberta and Saskatchewan. It is, therefore, to be regretted that every year the leaves Of these beautiful trees are made unsightly by the presence Of large blackened areas, which may extend over their entire surface. In some years hardly a leaf on badly attacked trees escapes this disfigurement.By the middle Of June an examination Of the cottonwood trees around Lethbridge, Alberta, can hardly fail to reveal the presence Of small groups Of holes on the underside Of the leaves, (fig. 2) with perhaps a few smaller groups on the upper side also (fig. L, A).A closer examination Of these holes shows that they are never more than about 1 mm. In diameter and are polygonal in shape, being bounded by the finer reticulations Of the leaf veins. They do not entirely pierce the leaf but extend to the upper epidermis, which appears. As a transparent membrane when the leaf is held to the light. After a few weeks they become more circular in outline, and are surrounded with a cork-like growth.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.