“Why, Mary Frances, you talk as though I knew a lot on the subject!” said Billy, “when, as a matter of fact, I don’t begin to know anything. It seems to me that the more I study, the more there is to learn. “I’m willing,” he went on, “to tell you girls what I can remember of what Professor Weed told about insect pests and insecticides—but I do wish you were both boys!” “We don’t, though. Do we, Eleanor?” said Mary Frances. “I shouldn’t think you’d mind. You’re always with boys during the school term, and—I don’t believe they’d listen anything like as well as Eleanor and I will.” FOOTNOTE: [G] There are a few aphids which feed upon roots. CHAPTER XXIX SOME SPRAYS FOR GARDEN PESTS “REALLY, there is some truth in that,” said Billy. “I’m not certain that I can remember much about the subject; but, since you are so anxious to learn, my children, I’ll refer to my trusty note book, and read to you about— GARDEN PESTS If we examine the various insects which injure plants, we find they do the harm in two different ways, according to their method of feeding. The different methods of feeding are by— (_a_) biting; or, (_b_) sucking. _Biting insects_ have _mandibles_, or jaws. The biting insects most familiar to you are beetles, grasshoppers, and many “worms,” or larvæ. If you catch a grasshopper, and hold a blade of grass in an upright position close to its mouth, you will observe that the jaws do not move up and down, but sidewise. This is true of all insects. It is quite easy to see the holes in leaves, bark, flowers or fruit where biting insects have been feasting. _Sucking insects_, instead of jaws, have a _haustellum_ or proboscis, which is a sucking tube, or beak, somewhat like a sharp hollow bristle. This they use to thrust down through outer layers of bark or leaves into the inner tissues where they draw up the sap or lifeblood of the plant. Among the sucking insects are aphids and scale insects. Now, it is an easy matter to throw poison on the parts of the plants that biting insects devour, where they will eat and swallow it, and then die; but it is almost impossible to place poison in the inner portions of the plants where sucking insects feed. Fortunately, most sucking insects have soft bodies which are easily destroyed; but it is a rather difficult task to do this work of destruction of sucking insects, because every insect must be touched by the destroying material to smother it, or destroy its breathing pores. Every farmer is familiar with some insecticides, or insect poisons. The trouble with using poisons, however, is that most poisons which will kill insects will also kill people, so it is better for young gardeners to use remedies harmless to human beings, but deadly to insects, of which there are a few.[H]