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CHAPTER VII ORCHARD, GARDEN, AND FIELD INSECTS SECTION XXXI. INSECTS IN GENERAL The farmer who has fought "bugs" on crop after crop needs no argument to convince him that insects are serious enemies to agriculture. Yet even he may be surprised to learn that the damage done by them, as estimated by good authority | CHAPTER VII 69 CHAPTER VII ORCHARD GARDEN AND FIELD INSECTS SECTION XXXI. INSECTS IN GENERAL The farmer who has fought bugs on crop after crop needs no argument to convince him that insects are serious enemies to agriculture. Yet even he may be surprised to learn that the damage done by them as estimated by good authority amounts to millions and millions of dollars yearly in the United States and Canada. Illustration FIG. 136. ANTS Every one thinks he knows what an insect is. If however we are willing in this matter to make our notion agree with that of the people who have studied insects most and know them best we must include among the true insects only such air-breathing animals as have six legs no more and have the body divided into three parts--head thorax and abdomen. These parts are clearly shown in Fig. 136 which represents the ant a true insect. All insects do not show the divisions of the body so clearly as this figure shows them but on careful examination you can usually make them out. The head bears one pair of feelers and these in many insects serve also as organs of smell and sometimes of hearing. Less prominent feelers are to be found in the region of the mouth. These serve as organs of taste. Illustration FIG. 137. PARTS OF AN INSECT Illustration FIG. 138. COMPOUND EYE OF DRAGON FLY The eyes of insects are especially noticeable. Close examination shows them to be made up of a thousand or more simple eyes. Such an eye is called a compound eye. An enlarged view of one of these is shown in Fig. 138. Attached to the thorax are the legs and also the wings if the insect has wings. The rear portion is the abdomen and this like the other parts is composed of parts known as segments. The insect breathes through openings in the abdomen and thorax called spiracles see Fig. 137 . An examination of spiders mites and ticks shows eight legs therefore these do not belong to the true insects nor do the thousand-legged worms and their relatives. Illustration FIG. .
