Beside the Tortoise, there are many creatures which possess natural shears, such as the Locust, whose ravages are only too notorious. Then, taking our own country, we have plenty of examples of insect shears. Such is to be found in the jaws of the Cockchafer larva, or “White Grub” as it is popularly called. It lives underground, and feeds chiefly on the roots of herbage, shredding them to pieces with its shear-like jaws. And, as it spends on the average three years in the one task of perpetual eating, the damage which it does can be easily imagined.
There is a very pretty English insect which admirably exemplifies the power of the natural scissors. This is the Great Green Grasshopper (Acrida viridissima), which is equally voracious in all its stages of existence. It is always ready to use these jaws, and I do not recommend the reader to allow his finger to get between them, or their points will probably meet.
One of these insects, indeed (Decticus griseus), has derived the name of Wart-biter from its supposed use in curing warts. All that was needful was to catch a Wart-biter, and hold one of the warts to its jaws. It was sure to seize the wart, and bite it smartly, and there was a firm belief that any one thus bitten would be freed from the unsightly excrescence. The bite of the shear-like jaws caused much pain at the time, and this very pain had in all probability something to do with the cure.
An admirable example of the insect jaws used as scissors is to be found in the well-known Leaf-cutter Bees, insects belonging to the genus Megachile.
They make their nests in burrows, sometimes in wood, and sometimes in the ground, and form them in a very singular manner. After fixing upon a suitable burrow, the Bee goes off to a tree, generally a rose, and, using her jaws just as a tailor uses his shears, cuts off a nearly semicircular piece of leaf, flies away with it to her home, and, by dint of bending, pushing, and pulling it, she forces it to the bottom of the cell. Successive pieces of leaf follow, until she has made a thimble-shaped cell, and she then places at its end an egg and a supply of honey and pollen.
Cell after cell succeeds, each being introduced into its predecessor just as thimbles are packed. Judging from a specimen in my collection, there are about eight layers of leaves to form the walls of the cell, and the average length of each piece of leaf rather exceeds half an inch. The entire length of the cell-group is two inches and a half. The leaf-slices are always cut from the edge, and, in my specimen of the nest, the serrated outer edges of the leaves are all in one direction.
Should any of my readers find one of these nests, it will be as well for them to dip a needle point into diamond cement, and introduce it under the outermost coating of leaves. Otherwise, when the leaves are dry, and the insects break their way into the open air, the cells will probably fall to pieces.
These Bees are much more abundant than is usually thought. In summer-time it is hardly possible to find a rose-bush on which are not a number of leaves from which pieces of variable size and shape, but always with a curved outline, have been cut as with scissors. While cutting them, the Bee seems to trace out her pattern, as it were, by using her feet like one leg of a pair of compasses, and her head as the other leg. As soon as she has nearly finished the operation, she poises herself on the wing, to prevent her weight from tearing away the leaf irregularly, and then, while still on the wing, makes the last few bites, and severs the leaf entirely.
The Chisel and the Adze.
Already we have seen how exact is the analogy between the scissors and the turtle-jaw. As we are upon the subject of cutting instruments, we will continue it, trying to discover some further analogies.