Insects that Build Submarines

Insects that Build Submarines

By A. Hyatt Verrill

Everyland magazine August 1916. Column, ‘Everyland Nature Club’; digitized by Doug Frizzle, Dec. 2011.

THAT sounds funny, doesn't it? Perhaps you think it's a joke, for we're so accustomed to think of submarines as wonderful inventions of our own that it's hard to believe such tiny things as insects made and used submarines ages before man first thought of building a boat of any kind.

But, queer as it seems, insects do build and use submarines and moreover they are very common, and any reader of Everyland who lives near a pond or stream—in temperate America, at least—can find these interesting little chaps and can watch them as they move about beneath the water. Even better, you can catch them, carry them home in jars or pails of water, and keep them in your own home in an aquarium where they'll be just as happy and interesting as ever.

But you musn't expect to find these insects rushing about in tight steel submarines and destroying other insects by torpedoes or mines. No, indeed! The submarines built by the insects are used for very different purposes and are made very differently from those which men use for the purpose of destroying ships and killing their fellow men.  The insects use their submarines for their homes and to protect themselves from enemies; and comfort and convenience, as well as safety, are far more important to the insects than are speed and destructiveness. But the insects' submarines are very cleverly and neatly built and are upholstered with the finest of silk. And the insect owners don't need periscopes nor machinery in their tiny submarines, for they are moved about by means of their owners' strong feet and never have to come up to the surface of the water for air or to have a look about. If they did that, some hungry bird might see them and gobble them down, submarine, insect and all, and, moreover, it isn't necessary, for these queer insects can breathe and can see at the bottom of the water just as well as when they're at the top; which is something we humans cannot do with all our brains and science and inventions.

But now you must be curious to know what these funny insects are like, and what they are, and how they live, and so we'll take a stroll to some shady pool or sparkling brook and see them for ourselves.

Place your face close to the surface of the water and look carefully at the sandy bottom beneath. At first you may not see anything but a few pebbles, some little bundles of sticks and some funny little cylinders of sand. But don't be discouraged, and in a moment you will be surprised to see some of these objects move about upon the bottom. Take them out and they are apparently dead and inanimate and, unless you know the secret, you would never guess that these ordinary looking things are insects' submarines.

But if you should break one open you would find it a hollow tube lined with soft and shining silk and with a pale, whitish, caterpillar wriggling about inside and very excited and indignant at having his snug home destroyed.

But it is much easier and kinder to watch the funny insects in a glass jar or aquarium, and in this way you may learn just how the caterpillar builds his submarine, how he makes it travel here and there, and, best of all, what happens when his short life is over.

If the little fellow thinks he's safe he'll cautiously move his head out from his silk-lined submarine home; then he'll look about and, if nothing frightens him, he'll crawl out until his little legs can grasp the object on which he rests, and then he'll walk about pulling his funny submarine with him.

And if you have sharp eyes and are interested in nature, and bugs, and live things, you'll notice that there are many different forms of these submarines. Some are little cylinders made of tiny sticks, or bits of grass or straws placed lengthwise side by side; others are like little log huts of the tiniest sticks or straws fastened together criss-cross; others are made of dainty little shells stuck together, and others are made of bits of moss and leaves, but most are made of tiny pebbles or grains of sand. But even these are of many different shapes. Some are like straight tubes, others are coiled like snail-shells, others are like little balls, and some are pointed at one end and look like the tusks of fairy elephants.

Although you cannot see any difference in the various caterpillars which make these submarines and live within them, yet each form of home contains a different kind of owner; and while they are all known as caddis-worms, there are many different species. Each specie always builds a certain kind of submarine house, each has distinct habits, and each is the larva of a pretty, winged insect known as a caddis-fly.

Some of the submarine caterpillars are carpenters, some are masons, and, in addition, many of them are expert fishermen and spread silken nets between the stones to capture their prey. Their tiny nets are funnel-shaped with the larger end pointed up the stream, but another kind of caddis-worm weaves little oval cups which are fastened to rocks on the edges of falls and cataracts. Both kinds of nets are kept open by the current and any minute creatures which are so unfortunate as to enter them are devoured by the hungry little builders of the submarines.

But the nets catch all sorts of dirt and rubbish as well as live things, and you often may see rocks completely covered with dirt which has lodged in the insect fishermen's nets and has hidden them completely out of sight.

By and by, when the caddis-worm has grown to full size, he feels dull and sleepy and drawing himself inside his submarine he closes his odd home with a silken door, leaving a tiny window for the water to enter, and then goes sound asleep. As he slumbers he wriggles out of his skin and changes to a shiny brown pupa or chrysalis. Then at last his sleep is over and the pupa bursts open and a queer little insect, very different from the caterpillar, gnaws through the silk door. It is a funny, damp creature with two long legs, and, using these legs for oars, the little fellow swims up to the surface of the water toward the nearest rock or stick.

Somehow he seems to have forgotten all about submarines and fish-nets, and, anxious to get to the open air, crawls up out of the water. Then a very wonderful thing happens, for two little pads upon his back swell up and change as if by magic into four delicate, hairy, brown wings. All his life this insect has lived at the bottom of the pond or brook; all his life he has crawled about, dragging his submarine house, or has slept inside a brown pupa. Never before has he been out of the water, never before has he possessed wings, and no doubt you think he'll have trouble learning to use them. But in that you'll be greatly mistaken, for no sooner do the little pads unfold than the caddis-fly spreads his new wings and flies away as gaily as though he'd used them all his life.