dime. In warmer seas the urchins grow large, even as large as a large
orange. People often use these larger ones for food.
The sea-urchin walks on his spines, as the cross-star-fish does on his.
But as the quills of the urchin are all around him, like a ball-cover,
his walk is a roll! By the little suckers he can cling to the rocks,
and he can climb up their sides.
Turn over the bare urchin shell, and you will see that while at the top
it has no opening larger than a pin-prick, on the under side there is a
hole where the curved rays do not come entirely together. You see the
urchin must have this open place for his fish-lines, and to put food
into his ever-hungry mouth.
Since the sea-urchin eats so much, he must grow! Does he?
Yes, the sea-urchin grows, and it cannot cast its shell as a crab can.
It has not a soft skin as you have, yet his shell is never too tight.
How can the shell expand as the urchin grows?
The shell is made up of a great many little plates, or scales. As the
urchin within grows and needs more room, these little scale-plates grow
larger all around.
Here is a strange thing: these wee plates are set like bricks in a
dome. You know the urchin is made on the five-ray pattern bent like a
flattened ball.
About the body of the urchin, within the shell, is wrapped a soft,
pretty, silk-like mantle. This mantle lines the shell. It takes lime
from the sea-water and builds it into more shell along the five edges
of these wee plates. It also adds new plates.
So, as the urchin keeps growing all the time, its mantle is building
upon the plates all the time. The house or coat, whichever you choose
to call it, grows with the growth of its owner. I think your mother
would be glad if she could find you a coat to grow with the growth of
your body.
The shell part of the urchin is gray or greenish gray. The quills are
often red, brown, pink, or purple. When a number of these urchins are
fast upon a rock, they look like a bed of lovely fringed flowers.
The urchins are able to bore holes even in the hard limestone rock.
They bore these holes to live in, and, as they grow, they make the
holes larger, but not the openings. So, after a time, they are shut
into a prison which they have dug for themselves. They do not do this
on our coast.
On the coast of Spain you will find the rocks covered with these
urchins, fixed in holes. No doubt they feel that stone walls are safe
walls. If they had wished to get away, and go and come freely, I think
they could have made their doorways as large as themselves.
There is much more to be learned about sea-urchins. You will do well to
study them when you can. In fact, the longest life is not long enough
in which to learn even what is to be learned of very simple and common
things. There is danger that when we have learned a little we shall
become proud, and that we shall not take the trouble to learn the very
much more which we do not know.
LESSON XLI.
THE FLYING FLOWERS.
You have just read about some of the Radiate Family. From their beauty
they have been called Flowers of the Sea. We will now hear about some
insects which might be called Flying Flowers.
I knew a little boy who, the first time that he noticed butterflies,
cried out, “Oh, see all those flowers flying!” That was a pretty idea.
It well described the butterflies, as you will see when you come to
read about them.[20]
There is another family of insects which also deserves the name of
Flying Flowers. Their shape, colors, and motions are very lovely. These
insects are the Dragon-Flies.
I am sorry that such beautiful creatures have had harsh names given to
them. They are called Dragon-Flies, Horse-Stingers, Darning-Needles,
Spindles, and so on. These names have nothing true in them. These
pretty insects never harm any one.
The French people call them Little Ladies. Now, that is a nicer name.
It is given to them because they are graceful and pretty, and also neat
and delicate, in their looks and motions.
[Illustration: A Flight of Dragon-flies.]
I knew a man who called these insects Air-Jewels. That was because they
are almost always on the wing, and their eyes and bodies flash and
shine like precious gems.
I have known silly people to start and scream when one of these
dragon-flies came darting by. That was foolish; they might as well
scream at a rose or a violet. There is no need of running away from
one of them. The great trouble is that they are so swift and shy, you
cannot easily catch one if you wish to examine it.
The dragon-flies are cousins of the termites, the may-flies, and the
lace-wing flies. They have four large, fine, lace-like wings, divided
into a great many spaces or meshes.
The two pairs of wings are nearly or quite equal in size. The head
is large. The body is long and light. They are very active in their
motions, and are very seldom at rest. They fly so swiftly that you
can scarcely see their thin wings, but only the flash of their
bright-colored bodies.
Dragon-flies like damp or wet places. You will find them above lakes
and ponds. They fly over marshy places or by the edges of quiet streams.
Go out to some still, silver-like pond, where the tall trees stand in
a ring about the water. The ferns, the tall yellow spikes of the St.
John’s-wort, and the blue clubs of the arrow-plant make a wreath around
the sandy margin. There you will see hundreds of gay dragon-flies
darting up and down. They swing in the sunbeams, as if glad to be alive.
In their great beauty the dragon-flies are as pretty as the
butterflies. Like them, they love the sunshine. They are the
children of the summer time. The hotter the weather, the happier the
dragon-flies seem to be.
Let us look for a little time at a dragon-fly. It belongs to the class
of the ring-made creatures. Its body is made in rings, and its feet
and legs are jointed. The body is very long and slim. Some kinds of
dragon-flies have the body rather flat, but usually it is round, is
slimmest in the middle, and thickens a little both at the tail and
where it joins the breast.
The wings of the dragon-fly are horny and of iris or golden hues.
Sometimes the body is a vivid blue or bright green. Sometimes it is
banded or spotted with yellow or scarlet.
The wide wings look like delicate lace spread on a fine frame. A little
child who found one of these wings, brought it to me, saying, “I dot a
dood piece of lace!”
The head of the dragon-fly is large, and has on each side what you
would call a great eye. But like that of the house-fly, this eye is
made up of many eyes set so as to seem to be one. I hardly dare tell
you how many there are--over twelve thousand! Through these wonderful
eyes the light plays and flashes like fire. Between these big eyes
three little simple eyes are set in a band across the head.
The dragon-fly has a queer mouth. The jaws are hidden under two thin,
skin-like lips. These move up and down as it eats. It does not suck
food, like the butterflies and house-flies, but eats after the manner
of the beetle.
Thus, you see, the dragon-fly belongs to the great Division of the
Eaters, not of the Drinkers. Instead of feeding on nectar, as we would
think so lovely a thing should, it eats insects.
All its life long, from the egg, it is always greedy, because it is
always hungry. It spends all its time hunting for food. Who could count
how many small insects a dragon-fly, eats in his short lifetime?
FOOTNOTES:
[20] See Seaside and Wayside, No. 3.
LESSON XLII.
UNDER THE WATER.
Now let us hear the story of the dragon-fly from its beginning. While
it is an egg, a larva, and a pupa, it lives under the water. Only when
about to burst from the pupa-case, and at last get its wings, does it
leave the water and seek the upper air.
In all its early stages the dragon-fly lives in cool, still shallows,
among green and graceful water-plants. There the sunshine glows all
about it, as it darts over the bottom of the pond, hunting for food.
The mother dragon-fly, as she flits over the water, drops her eggs upon
it. They sink to the bottom. She may put them into plant stems. Their
cases are waterproof. If the eggs are not eaten up by beetles and other
fellow-citizens under water, they are quite safe, and soon the larvæ
hatch out.
[Illustration: Home of the Dragon-fly.]
Most insects move quickly in the larva state, and are dull or quite
asleep in the pupa-case. This is not the way with the dragon-fly. He
is busy and strong all his life. The egg settled upon the pond bottom
is quiet; the larva moves about, but is rather slow and lazy. The pupa
dashes here and there, and frightens all the little animals in the
pond. At last the perfect insect rises on the wing. It darts about with
almost the swiftness of light.
The larva of the dragon-fly is gray. It has six legs. It is always
hungry, and feeds on small water-animals, as beetles, grubs, shrimps,
leeches, and their young.
This larva does not run after its food, but lies waiting for it. On the
bottom of the pond, hidden in the shadow of a leaf, root, or stone,
or seated on stems or leaves that are under water, the larva waits
patiently for its prey to come by.
Did you ever see a person with a net for catching insects? This net
is a fine bag set on a little hoop. The hoop is fastened upon a long
handle. Sometimes the handle has joints, and will fold up. As insects
dart by, the person with the net brings it down over them with a quick
motion.
The dragon-fly larva has something much like this with which to catch
its food. The lower jaw is fastened by a hinge to a little jointed rod.
The rod, and the jaw-plate upon the end of it, when not in use, are
folded down upon the head of the insect.
The plate has fine teeth upon its edge. When the prey comes by, the
larva snaps out its rod, with the plate, as if they both were on a
spring, and so catches the things that are swimming along a little way
off. They do not see their foe, and do not know that he can reach so
far with his sweep net.
The teeth on the edge of the plate shut up, and then the rod folds
back, and puts the food into the hungry larva’s throat. I suppose the
little creatures that swim along feel quite happy and safe, and then,
all at once, out springs this weapon, and they are gone.
But this little plague of the pond is not quite safe himself. There are
some other creatures down under the water that eat him. All nature is a
kind of game of “tit for tat,” you see.
The larva of the dragon-fly breathes air. He has no lungs as you have,
but gills as a fish has. How does he get air?
Through his body goes a long tube. The tube ends in a horny point at
the tail. This point is made of five very fine spikes. These spikes and
this tube are able to take from the water some of the air that is in
it. Thus he gets air much as a fish does.[21]
This spike on the tail of the larva has a very strange use. It shoots
out the water which it has taken in, as you would shoot water from a
squirt-gun. It shoots the water out with such power that it drives the
larva along in the water.
Did you ever see a steamboat driven through the water by a screw or
wheel at the stern, or hind part? What do you think that the man who
first made such a boat said? He said that he took his idea of how it
should be made by seeing this queer larva move in the water.
When this creature seizes food, he likes to strike it from below. He
rises under it in the stroke, as the shark does. Dragon-fly larvæ are
very bold. They can eat large and hard insects.
When the larva changes to a pupa, it becomes more lively, fierce, and
hungry than ever. It does not change its form at this time as much as
most insects do.
The dragon-fly pupa has six legs, and each foot has strong hooks on it.
Its color is pale brown, clear and shining, and its case is horny. Some
rings of the body have horny spikes upon them. Upon the case of the
chest is a pattern like wings.
These pupæ dash about the bottom of the pond, swimming or running, and
eat almost everything that lives there. The body and head of the pupa
are thicker than those of the grown-up dragon-fly. They are made for
seizing and killing prey.
When it is nearly time for the pupa to come out as a dragon-fly, the
case grows clearer, like glass. The large, beautiful eyes grow brighter
and brighter, and the pupa leaves the deeper part and gets near the
edge of the pond.
FOOTNOTES:
[21] See Seaside and Wayside, No. 3. Lessons on Fish.
LESSON XLIII.
A HAPPY CHANGE.
When the close of the pupa state draws near, the coming dragon-fly
loses its fierce appetite. It seems to feel tired and heavy. It
breathes slowly, as if it could not get air enough. The body has
changed inside the horny case, and the time is near when it will leave
the water for air, and walking for flying.
Once the larva wanted nothing better than to chase bugs about under
water. Now, all at once, it longs for the free air and for the sun. It
needs no one to tell it what to do. In some way it knows exactly how it
should act.
This tired pupa now seeks the stem of some tall reed or grass that
grows in the water. Slowly it crawls up the stem. The hooks on the feet
take fast hold as it goes, and it keeps on until it is nearly a yard
above water.
The hooks, though very small, are so sharp and hard that they can go
into wood. When the pupa is as high up as he wants to be he drives the
hooks into the stem. Thus it will hold firm even when it twists and
struggles hard.
The pupa likes best to find two reeds or stems near, so that it can
take hold of both and swing between the two. Then, like a child in a
swing, it begins to sway to and fro. Now, as it sways, a strange thing
happens. The hard pupa-case splits open upon the back, and look, inside
the case, we see the perfect insect, with its wings!
The pupa-case is firmly held by its hooked feet, while the new insect
twists and pulls, and so gets free; and little by little its head,
legs, wings, and long body come forth, and finally hang only by the
last ring of the body.
[Illustration]
Then you would think it was dead. For after it stretches out first one
leg and then the other, it hangs by its last ring, stiff and still. But
it is only resting. After about fifteen minutes it awakes. Taking hold
firm with its feet upon a stem or leaf, it lets go its hold upon the
pupa-case. That is left hanging by its hooks in its place.
Here is now a dragon-fly, with large head, with two great cluster eyes,
six legs, four wings, and long, bright-hued body! And now, at last, it
can breathe freely through all those tubes and air-holes you have been
told about.
Still the insect does not look like the full-made dragon-fly. The
colors are dull, and the wings are folded up. The body is soft, damp,
and too short. The big eyes are dim.
[Illustration]
As if half asleep it still clings to the stem, not far from the case,
which is the old shape of itself. Hanging to the reeds by the pond you
will often find these old coffins, if you look for them.
The new insect is drawing in the sunshine and fresh air. It stands
still and breathes hard, filling its new body with pure, dry air. Now
and then its wings quiver.
As they quiver they spread out, fold after fold, as silken banners wave
out upon the air. Then at last they are spread out wide, in all their
beauty. The dragon-fly has reached its last and highest state. It can
sail away where it pleases on its new wings.
As the wings grow larger, the eyes of the dragon-fly grow brave and
bright; its body dries. Then it gleams like a jewel. Its fresh colors
come out clearly. It feels strong and active.
Then, all at once, it uses its new wings. It rises into the air and
flashes here and there, just as hungry and ten times swifter than ever
before.
The flight of the dragon-fly is called hawking, for it is like the
motion of that strong bird, the hawk. If it gets caught in a place
where its wide wings cannot turn, it can fly backwards and get off
safely. In a place where the wings might be injured by striking against
leaves or branches, it flies out in this way.
When dragon-flies are dead, the great beauty of their bodies passes
away. They fade and grow dull, as when they first came from the
pupa-case. The scarlet, yellow, blue, or green turns to a dull drab. So
you cannot keep them as well as you can keep beetles. It is life that
gives the dragon-fly its splendid beauty.
LESSON XLIV.
THE DRAGON-FLY AND HIS COUSINS.
The dragon-fly eats almost every kind of insects which you have thus
far read about. Beetles, spiders, flies, centipedes, fresh-water
shrimps, and polliwogs are its food.
The dragon-fly is a larva for a year. It is a perfect dragon-fly only
a part of one summer. You will find the most dragon-flies in July or
August. When the frost comes, they die.
Dragon-flies are very strong; they are fond of chasing other insects.
They seem to catch and tear them for the mere pleasure of pulling them
to pieces. They also fight with each other, and Mr. and Mrs. Dragon-fly
have some hard battles.
The dragon-fly does not have a long lip, or mask, set on a rod, as
the larva had. They fly so swiftly that they do not need such help in
getting food.
Few insects are so easy on the wing as this, and few have such
beauty of wing. Yet I think, after all, that the chief beauty of the
dragon-fly is in its eyes. These are like two great flaming jewels.
The eyes are beautiful, for this clear, glowing light in them; the
body, for vivid color; the wings, for their lace-like texture. Each of
the wings has a dark spot on the front edge. Often, in flying, this
spot and the line of bright color of the body, almost like a streak of
fire, are all that can be seen of the insect.
[Illustration: The Dragon-fly and his Cousins.]
There are several kinds of dragon-flies. These are different in color
and size, and in the shape of their bodies. One, with a very long,
thin, dark body, is called the Darning-Needle. One, with a thicker
body, is called the Ringed-Club. Its body is largest at the tail end.
This one is dressed in black and gold, and is large and strong.
A smaller kind of dragon-fly, which has no spots on the wings, is
called the Little Lady. This is among the prettiest of all; some of
them are bright red; some a clear light blue. They look more like
creatures in some dream about fairies, than like real live insects, for
they flit here and there like streaks of gay-colored light, and you can
scarcely see the wings on which they fly.
The dragon-fly has some very handsome relations. One of these is called
the Lace-Wing. The head and body of the lace-wing are bright green, its
wings are like white gauze; but its chief beauty is in its eyes. Some
call it the Golden-Eye, because its eyes are like a drop of amber, or
melted gold.
The veins in the wings of the lace-wing are very fine. As the light
falls on them, they change in color, and look like pink, red, blue,
green, or gold threads.
These lovely lace-wings do not like the bright light of the noon-day,
as the dragon-fly does. They prefer to come out in the moonlight, or
when the sun is setting.
The lace-wing is not a water lover, as the dragon-fly is. It lays its
eggs on leaves, and every egg is held upon a little silken stem. The
stem is much like the silk which the spider spins. These eggs are laid
in groups.
When the young lace-wings come out of the eggs, they feed on the little
aphis. You remember the aphis makes the honey that ants are so fond of.
In two weeks these larvæ change to pupæ. To do this the lace-wing larva
spins a nice silk ball, in which it goes to bed for a nap while it is a
pupa.
In this, you see, it is not at all like the young dragon-fly, which
hunts and runs about while it is a pupa. The ball of the sleeping
lace-wing is about the size and shape of a wild pea, or vetch seed.
The lace-wings are short lived. One summer makes a lifetime for them.
In a summer they grow from infancy to age, make all their changes, and
live out their time as complete insects.
When the lace-wing is dead, it loses all its fine colors in a very few
hours.
LESSON XLV.
THE WINGS OF THE DRAGON-FLY.
We can find no better example than the dragon-fly, of the way in which
insects behave when they leave the pupa-case.
You know that this case is horny or tough, and always seems smaller
than the grown-up insect; so the insect must be very closely packed in.
No person could pack a new insect back into the case it has just left.
While the dragon-fly pupa is under water, the case is kept tough, and
yet soft enough to bend. But when the pupa crawls up the stem of the
plant into the air, the case soon dries and becomes brittle.
As the fly struggles within, the dry case will easily split. The little
wet coat, which covers the body while it is in the case, makes it more
easy to slip out of the shell when it cracks open. You know if you have
on your finger a ring which is too tight, you can pull it off if you
wet your finger.
The wet coat of the fly in the case keeps the wings from being hurt by
their close folding. After they are dry and spread out, they are easy
to break. Then it is very easy to hurt or spoil them.
The fly seems to know this, and is careful of its wings. In the act of
unfolding, the fly holds its wings from touching any object, even its
own body.
When the dragon-fly gets free from the case, it knows just how to
spread its lovely wings into perfect shape. It stands quite still, and
far enough from stems or leaves to keep its wide wings safe.
It does not move its wings, but lets the air do the work, while it
holds its bent body away from the wings. The quiver you see through it,
now and then, is a motion of the body; and I will soon tell you what it
means.
When the fly first comes from the case, its wings are soft, and will
bend as easily as wet paper. After they are dry, they are like thin
plates of glass. These wings have very many nerves through them. Their
frame is like a fine net-work, and, as it is touched by the air, it
spreads slowly to its full size. If, at this drying-time, the wings are
hurt, they will never come to their right shape.
[Illustration]
If any one should try to help a dragon-fly out of its case its wings
would be ruined and never take their right shape. Human hands are too
clumsy for such work.
When first the pupa comes from the case, the wings and body are of a
dull, faded color. But as it stands in the sun and air, you can see it
change from minute to minute.
Fold after fold of the wings shakes out; ring after ring of the body
stretches to its proper length; the joints of the legs come to their
right shape and firmness. From all the body of the insect a mist seems
to pass away; and the colors of the fly come out, and red, blue, green,
gold, shine in beauty.
Now let us look closely at these fine wide wings. Although they are so
thin, like gauze, yet they are double. There is a surface on each side,
spread over a very fine frame. The parts of this frame are small as the
finest hairs.
And yet, though so tiny, they are all hollow. They are tubes or pipes.
They carry through the wing, air and a very thin white fluid, which is
the blood of the insect.
Now that you know this, can you clearly see how the wings expand? As
soon as the dragon-fly is born from its pupa-case, air and this thin
fluid are driven through these fine tubes. As they fill, they stretch
out, and the thin surface which covers them spreads with them.
If you notice the fly as it is thus getting its shape, you will see
that quiver which I spoke of. That motion is the pumping of air and
fluid through its tubes; and, no doubt, by this action the fly spreads
out its wings and its body. By such a motion the blow-fly spreads out
its big head.
The dragon-fly spends about fifteen minutes in getting into shape.
Sometimes half an hour is needed. After that, the fly rests for an hour
or two, before it tries its wings in the air. Very likely it wishes to
give its wings time to get quite firm and hard.
Butterflies, Lace-Wings, May-Flies, and other insects of the kind have
their wings made in this way; so what you learn about one will help you
to understand the others. You read of the Lace-Wing in the last lesson,
and in the next book you will hear about Butterflies.
The May-Flies are very pretty insects. They are something like
dragon-flies, but very much smaller, and not fond of tearing up other
insects. You will find them in moist places. The body of the May-Fly is
much slimmer even than that of the dragon-fly. The wings are unequal.
Their heads are smaller. May-Flies have two fore legs, nearly as long
as the body, held almost straight out as they fly. On their tails they
have three long stiff hairs, twice as long as the body. These hairs
spread out, fan-shape.