XII.—CATERPILLARS. “We found these upon the dead-nettle.” As he spoke, Frank opened a small cardboard box and showed his uncle half a dozen large, hairy caterpillars. [Illustration: Larva Cage.] “Splendid,” said Uncle George. “We will just put these into the cage.” Uncle George, who was a very good carpenter, had of late been busy in his spare time making a box or cage for keeping caterpillars in. He called it a _larva cage_. It was a curious looking thing, something like a small meat-safe. Three sides and the top of it were covered with gauze. The fourth side was a large pane of glass. The gauze-covered side opposite to this opened as a door. It was divided into an upper and a lower part by a shelf in the middle, and, by sliding in two pieces of wood, it could be divided into four tiny rooms. Now that it was finished, Uncle George wanted to get it stocked, and his two nephews wanted it stocked too. “Do you want any more of these woolly caterpillars?” Frank asked. “No, Frank, but you can bring me in some more of a different kind. Or, better still, let us go out into the garden now and see if we can find any there.” The gardener beamed with joy when Uncle George told him what they had come to the garden for. “Caterpillars?” he said. “I wish you would take them all, sir. They are the worst vermin in the garden. Last year they left scarcely a leaf on my currant bushes.” Our three friends went straight to the currant bushes. Here they found a good many pretty little caterpillars of a creamy colour, richly striped with orange, and dotted over with black spots. These, their uncle informed them, were the caterpillars or _larvæ_ of the magpie moth. On the cabbages they found several caterpillars of the large white butterfly. These were bluish green in colour, with three bold yellow stripes running along the whole length of their bodies. “What are these, Uncle George?” Tom asked, as he turned up a cabbage leaf and pointed to several white patches on its under side. The leaf next it was spotted just like it. “Oh, Tom, how lucky we are! These are the eggs of the large white butterfly. Now we shall be able to follow up the whole life of this insect, and a wonderful life it is. Let us go right in and examine them. Take some cabbage leaves and some currant leaves to feed the hungry caterpillars with.” “Our larva cage is now quite full,” said Uncle George, when he had put the caterpillars in. “Why do you not put them into the same room, Uncle George?” “There are two reasons for that, Frank. First, they live upon different kinds of food. The hairy caterpillar, or ‘woolly bear,’ as boys call it, feeds upon nettles, the cabbage caterpillar prefers cabbage leaves, while the currant caterpillar will only eat currant leaves. [Illustration] 1. Caterpillar and Eggs of Cabbage Butterfly. 2. Egg magnified.