“Look at this root, quite covered with ugly warts, hollow inside. I open one. What do we find within? A small worm, a larva that would, if left undisturbed, develop into a weevil with a beak that lies down on the breast between the forelegs when the insect curls up and plays dead. This weevil is known to men of science as belonging to a genus called ceuthorhynchus, a name formed from two Greek words and meaning snout-hider. It is black, with grayish hairs on the back and white scales on the belly. Its thorax has a deep furrow and its wing sheaths are ornamented with fine parallel grooves.
“It lays its eggs about the beginning of summer. The insect works its way down to the root and punctures it here and there with its beak, laying an egg in each puncture. In flowing around the wounded part the sap of the plant forms a knob or fleshy wart in which the larva grows until the end of October, when the worm leaves this nest to bury itself in the ground, safe from the cold, and undergo transformation. The punctured root exhausts its energies in bleeding sap to form the warts occupied by the larvæ, so that the cabbage rapidly withers away; and in this manner the cabbage-weevil makes itself an enemy much to be feared, especially in England where it is extremely common. Nor does [[335]]it confine its depredations to cabbages; it attacks turnips also, and radishes and rape.”
“This weevil seems to eat a good many things,” said Jules. “I thought each kind of insect always fed on one particular plant.”
“You were not far wrong, my boy. In most cases insects have very exclusive tastes, each confining itself to one kind of plant and disdaining all others. Sometimes, however, they vary their diet, and as they are connoisseurs, very well up on vegetable flavors, in changing their food they choose plants having nearly identical nutritive properties, taste, and smell. Do not we ourselves find in the radish and the turnip something of the smell and taste of the cabbage?”
“That’s so,” assented Louis.
“We find more or less similarity in the qualities characteristic of a great many other plants grouped together by botanists in the family of cruciferæ and including, for instance, the cress, the radish, and colza.”
“Botanists, cruciferæ—I don’t know very well what those are,” said Emile.
“No, those are strange words to you. Botanists are learned persons who spend their time studying plants and who tell us their names and properties, differences and resemblances, where they grow and when they blossom, with other matters of that sort.”
“And cruciferæ?”
“That word means cross-bearers and is applied to a large group of plants with blossoms having four [[336]]pieces or petals placed two by two, opposite each other, so as to form a sort of cross. A good example is the colza blossom. Plants with cross-shaped flowers include the cabbage, rape, turnip, radish, clove, colza, cress, and many others.”