“The tool for chipping away the wood consists of two curved fangs or teeth, almost black, one on each side of the mouth, which open and shut like a pair of cutting nippers. They are called mandibles and are in reality jaws or, more properly, teeth which, instead of meeting in a vertical plane as do ours, come together horizontally or sidewise. For precision of movement these mandibles are superior to our best cutting nippers, and for hardness they are almost equal to steel. They seize the wood, bit by bit, patiently and untiringly; they cut, saw, tear away a little at a time, and so bore a tunnel just large enough for the caterpillar to pass through.” “And what becomes of the wood-dust?” Jules further inquired. “I should think it would block the way, the passage being so narrow.” “The wood-dust passes through the creature’s body; the caterpillar eats it, and after digestion has taken from it the very small amount of nourishment it contains, it is ejected behind, molded into tiny pellets. Digestion in a caterpillar is soon accomplished. Just think of it: wood is an extremely meager fare, and so the worm must keep on eating its way forward, cutting, gnawing, digesting. To acquire the fatness necessary for the coming change the creature must have a good-sized pear-tree limb or lilac trunk to work on. “The wormhole dust left behind by the boring worm sometimes betrays the insect to its enemies. Whenever you see any of this dust left by digestion coming out at some little orifice in the bark of a pear-tree, apple-tree, or other tree, you may know the borer is at work, and the branch where he is at work should be cut off immediately, to prevent more serious harm. If the caterpillar has not gone too far, a pointed iron wire may be thrust into the opening and an attempt made to kill the creature in its hole. But as the passage is very winding, this method is by no means certain of success.” “Couldn’t the wire be pushed in through another opening?” queried Jules.