th it, and when it is frightened it pops back into its little stone
case.

Mollie says it reminds her of a hermit crab.

A hermit crab, you know, lives on the seashore and takes possession of
an empty snail shell for a house.

It comes partly out dragging its house with it, but if you disturb it,
it draws back, sometimes quite out of sight.

[Illustration]

This little larva lives in a house, too, but it is a house of its own
making.

It is the larva of the caddice fly, or case fly.

Let us put one of these little sand cases in the saucer here.

Please fill the saucer about half full of water, John. Thank you.

Now, Mollie, I see you have picked up a fine big caddice case.

Put it in the saucer, and let us watch the larva crawl about.

[Illustration]

It never comes entirely out of the case, you see. It holds on to it with
the hinder part of its body.

Its little black head is hard, but its body is soft, and that is why it
does not like to expose itself to hungry larvae that might be living in
the water.

May says she wants to see the whole larva.

Suppose we carefully break away the little sand case.

No, indeed, little Nell, we are not going to hurt the larva; we are only
going to open its house.

[Illustration]

There, the larva is outside now, and you can see what a tender, pale
little thing it is.

It does not like to have its soft body exposed.

See! it is already gathering little bits of sand together.

It seems to be sticking them fast to its body.

It is really binding them together by a saliva-like substance from its
mouth.

It draws out little glistening threads that harden into silk as soon as
they touch the water.

Queer saliva you think.

But the caddice larva does not find it queer. It is used to saliva that
hardens into silk.

Yes, that is the way the larva of the aphis lion and of the ant lion
made their cocoons. They spun out silk in this manner.

The caddice larva makes its house of silk and sand and also lines it
with a beautiful covering of fine silk.

Yes, May, it papers its walls with silk.

You see it did not hurt the caddice larva to take away its house; it
immediately went to work to build another.

Why not pull it out, instead of breaking its house to pieces?

Because if it had been pulled hard enough to come out, it might have
been torn to pieces, it is such a tender little thing, and it holds fast
so tightly.

So the best way to remove it safely is