"Very well, I will; do you think of some kind of tools that men use: think of the carpenter and his tools, and let us see if we cannot find some of them among the insects."
"Why, the carpenter has a saw. Is there any saw among these little fellows?"
"Yes indeed, there is; and a capital saw it is. Now listen, and I will tell you all about it. There is a kind of fly called the saw-fly; it has four wings, and commonly its body is yellow, and its head is black; but the most curious part of it is the saw. The young ones feed upon the leaves of rose-bushes, and gooseberries, and raspberries, and currants, and several other kinds of bushes; and the old ones always lay their eggs on the branches of these bushes, so that the young ones may have something to eat as soon as they come out. It uses its saw to make a place in the branch to put its egg in."
"Uncle Philip, what is the saw made of?"
"It is made of something like horn, and is fixed very nicely in a case; it resembles what the cabinet-makers call a tenon-saw more than it does the carpenter's common saw. The tenon-saw is made of a thin plate of steel, and has a stiff brass back, to keep it from bending. The brass back has a groove in it, and the saw is put in that groove, and then it is fastened to it. But the fly's saw is fixed in another way: there is a back to it too, but that back is not fastened to the saw. The groove is in the saw, and there is a ridge all along the back-piece, which just fits in the groove, and so the saw slides backwards and forwards, and the ridge always keeps it in its place. Besides all this, boys, the fly is better off than the cabinet-maker, for he uses only one saw at a time; but our little workman has two exactly alike, and they are so fixed that the creature first pushes out one, and when it is drawing that back, pushes out the other; so that it is all the time cutting, and does double work. I think the fly's saw is the best, too, for another reason. The saws of the carpenter and cabinet-maker have their teeth bent; first, one a little on one side, and then the next to it a little on the other side, and so on to the end of the saw; so that when sawing, the cut may be wide enough for the blade to move easily. Now the fly's saw has the teeth a little bent, or twisted, too; but it has something else: on the outside of every tooth there are a great many very small teeth, so that the outside of every one is just like a rasp, or file."
"But, Uncle Philip, it must take them a great while to saw a very little cut; they are so small."
"Yes, it does; but they persevere. It takes them more than an hour and a half to make one groove, and sometimes they will go on and make as many as six without stopping. That shows, boys, what perseverance will do."
"And when it is done sawing, Uncle Philip, where does it keep its saws?"
"Oh, I told you they fitted in a case; but when the fly is done sawing, it uses the saws to put the egg in the place cut for it, and then it draws the saws almost entirely into the case, and drops upon the egg a sort of frothy stuff like a drop of soap-lather."
"What is that for?"