Man struggles against these tiny monsters not only for his life and health but for his food as well. Almost every cultivated plant has its enemy, and some of them have many. The bugs alone which stick their beaks into all sorts of plants to suck their juices would starve man out in one or two brief seasons if they in turn were not held in check by enemies of their own. The chinch bug alone has demonstrated his power to devastate the wheat fields. The bark beetles that girdle square miles of forest trees, the moths that destroy their foliage, the creatures that burrow into the fruit and fruit trees, the gall-forming flies that form galls on the roots of the grape vines able to destroy the revenues of a whole country, the beetle which strips the potato of its leaves, the one which infects with its dirty jaws the melon vines of the South and turns the melon patches brown--these are a few of the vast array of our enemies. It would require a book much larger than this one just to enumerate those well known. It should make every American proud to know that it is the American economic entomologist who has, more than any other, pushed his way into this field and shown mankind how to fight these monsters which destroy his food, his animals and himself. But all these fascinating little creatures are not our enemies. We must not forget that man has domesticated certain of the insects and that gigantic industries depend upon them for their existence. The honey-bee furnished mankind with sweets during the generations preceding the discovery of the sugar cane, and the silk worm furnishes still the most costly raiment with which we clothe ourselves. The friends we have in the insect world are those which destroy the pests of our cultivated crops like the Australian lady-bird beetle which has been sent from one country to the other to keep in check the fluted scale which is so injurious to the orange orchards, and the parasites of the gipsy-moth which, in Europe, helps to keep under control this plague of our forest trees, must certainly be counted as our friends. Also, they are our friends if, like the spiders, they kill such monsters as suck our blood or make our lives unsafe, or, like the great hordes of wasps and hornets, wage unending warfare against the flies but which, because they attack us personally if we come too near their nests, we kill on sight. Strangely enough, it is often these same stinging insects which help us by fertilizing the blossoms of our fruit trees. Indeed many plants are so dependent on these little creatures that they have lost the power of self-fertilizing and thousands of species of trees and plants would become extinct in a generation without their friendly aid.