Chapter XXII: Part II: Animal Life (15)

The thorax is the middle region of the insect body. It is composed of three of the body segments more or less firmly joined together. The segment next the head is called the prothorax, the middle one, the mesothorax, and the hind one, the metathorax. Each of these segments bears a pair of legs and, in the winged insects, the second and third segments bear the wings. Each leg consists of two small segments next to the body, next to them a longer segment, called the femur, beyond this a segment called the tibia, and beyond this the tarsus or foot. The tarsus is made up of a number of segments, varying from one to six, the most common number being five. The last segment of the tarsus usually bears one or two claws.

While we have little to do with the internal anatomy of insects in elementary nature-study, the children should be taught something of the way that insects breathe. The child naturally believes that the insect, like himself, breathes through the mouth, while as a matter of fact, insects breathe through their sides. If we examine almost any insect carefully, we can find along the sides of the body a series of openings. These are called the spiracles, and through them the air passes into the insect’s body. The number of spiracles varies greatly in different insects. There is, however, never more than one pair on a single segment of the body, and they do not occur on the head. The spiracles, or breathing pores, lead into a system of air tubes which are called tracheæ (tra’-ke-ee), which permeate the insect’s body and thus carry the air to every smallest part of its anatomy. The blood of the insect bathes these thin-walled air tubes and thus becomes purified, just as our blood becomes purified by bathing the air tubes of our lungs. Thus, although the insects do not have localized breathing organs, like our lungs, they have, if the expression may be permitted, lungs in every part of their little bodies.

_Summary of Structure of an Insect_

⎧ Antennæ.
⎪ Compound eyes.
⎪ Simple eyes or ocelli.
Head ⎨ ⎧ Labrum, or upper lip.
⎪ ⎪ Mandibles, or upper jaws.
⎪ Mouth-parts ⎨ Maxillæ, or lower jaws, and maxillary
⎪ ⎪ palpi.
⎩ ⎩ Labium and labial palpi.

⎧ Prothorax and first pair of legs.
⎪ Mesothora and ⎧ second pair of legs.
⎪ ⎩ first pair of wings.
⎪ Metathorax and ⎧ third pair of legs.
⎪ ⎩ second pair of wings.
Thorax ⎨ Wing ⎧ veins.
⎪ ⎩ cells.
⎪ ⎧ Two small segments called
⎪ ⎪ coxa and trochanter.
⎪ Leg ⎨ Femur.
⎪ ⎪ Tibia.
⎩ ⎩ Tarsus and claws.

⎧ ⎧ ears (in locusts only).
Abdomen ⎨ The abdomen bears ⎨ spiracles.
⎩ ⎩ ovipositor.

_References._--Manual for the Study of Insects and Insect Life, Comstock.

THE BLACK SWALLOW-TAIL BUTTERFLY

_Teacher’s Story_

This graceful butterfly is a very good friend to the flowers, being a most efficient pollen carrier. It haunts the gardens and sips nectar from all the blossom cups held out for its refreshment; and it is found throughout almost all parts of the United States. The grace of its appearance is much enhanced by the “swallow-tails,” two projections from the hind margins of the hind wings. The wings are velvety black with three rows of yellow spots across them, the outer row being little crescents set in the margin of the wing; and each triplet of yellow spots is in the same cell of the wing between the same two veins. The hind wings are more elaborate, for between the two inside rows of yellow spots, there are exquisite metallic blue splashes, more vivid and more sharply outlined toward the inside of the wing and shading off to black at the outside. And just above the inner angle of the hind wing is an orange eye-spot with a black center. On the lower surface of the wings, most of the yellow spots are replaced with orange.

The mother butterfly is larger than her mate and has more blue on her wings, while he has the yellow markings of the hind wings much more conspicuous. She lays her egg, just the color of a drop of honey, on the under surface of the leaf of the food plant. After about ten days there hatches from this egg a spiny little fellow, black and angular, with a saddle-shaped, whitish blotch in the middle of its back. But it would take an elfin rider to sit in this warty, spiny saddle. The caterpillar has six spines on each segment, making six rows of spines, the whole length of the body; the spines on the black portions are black and those on the saddle white, but they all have orange-colored bases.

When little, spiny saddle-back gets ready to change its skin to one more commodious for its increased size, it seeks some convenient spot on the leaf or stem and spins a little silken carpet from the silk gland opening in its under lip; on this carpet it rests quietly for some time, and then the old tight skin splits down the back, the head portion coming off separately. Swelling out to fill its new skin to the utmost, it leaves its cast-off clothes clinging to the silken carpet and marches back to its supper.

Photo-micrograph by M. V. Slingerland.]

But after one of these changes of skin it becomes a very different looking caterpillar, for now it is as smooth as it was formerly spiny; it is now brilliant caraway green, ornamented with roundwise stripes of velvety black; and set in the front margin of each of these stripes are six yellow spots. In shape, the caterpillar is larger toward the head; its true feet have little, sharp claws and look very different from the four pairs of prolegs and the hind prop-leg, all of which enable him to hold fast to the stem or the leaf; these fat legs are green, each ornamented with a black, velvety polka-dot.

Photo by M. V. Slingerland.]

When we were children we spent hours poking these interesting creatures with straws to see them push forth their brilliant orange horns. We knew this was an act of resentment, but we did not realize that from these horns was exhaled the nauseating odor of caraway which greeted our nostrils. We incidentally discovered that they did not waste this odor upon each other, for once we saw two of the full-grown caterpillars meet on a caraway stem. Neither seemed to know that the other was there until they touched; then both drew back the head and butted each other like billy-goats, Whack! whack! Then both turned laboriously around and hurried off in a panic.

The scent organs of these caterpillars are really little Y-shaped pockets in the segment back of the head, pockets full of this peculiar caterpillar perfume. Under the stimulus of attack, the pocket is turned wrong side out and pushed far out making the “horns,” and at the same time throwing the strong odor upon the air. This spoils the flavor of these caterpillars as bird food, so they live on in serene peace, never hiding under the leaves but trusting, like the skunk, to a peculiar power of repelling the enemy.

We must admire this caterpillar for the methodical way in which it eats the leaf: Beginning near the base, it does not burn its bridges behind it by eating through the midrib, but eats everything down to the midrib; after it arrives at the tip of the leaf it finishes midrib and all on its return journey, doing a clean job, and finishing everything as it moves along. (See Moths and Butterflies, Dickerson, p. 42.)

When the caterpillar has completed its growth, it is two inches long; it then seeks some sheltered spot, the lower edge of a clapboard or fence rail being a favorite place; it there spins a button of silk which it grasps firmly with its hind prop-leg, and then, with head up, or perhaps horizontal, it spins a strong loop or halter of silk, fastening each end of it firmly to the object on which it rests. It thrusts its head through, so that the halter acts as a sling holding the insect from falling. There it sheds its last caterpillar skin, which shrinks back around the button, revealing the chrysalis which is angular with ear-like projections in front. Then comes the critical moment, for the chrysalis lets go of the button with its caterpillar feet, and trusting to the sling for support, pushes off the shrunken skin just shed and inserts the hooks, with which it is furnished, firmly in the button of silk. Sometimes during this process, the chrysalis loses its hold entirely and falls to the ground, which is a fatal disaster. The chrysalis is yellowish brown and usually looks very much like the object to which it is attached, and is thus undoubtedly protected from sight of possible enemies. Then some day it breaks open, and from it issues a crumpled mass of very damp insect velvet, which soon expands into a beautiful butterfly.

Photo by M. V. Slingerland.

_The caterpillar of the black swallow-tail ready to change to
a chrysalis._
]

_References._--Everyday Butterflies, Scudder; Moths and Butterflies, Dickerson; How to Know the Butterflies, Comstock; Moths and Butterflies, Ballard.

LESSON LXX

THE BLACK SWALLOW-TAIL BUTTERFLY

_Leading thought_--The caterpillars of the swallow-tail butterflies have scent organs near the head which they thrust forth when attacked, thus giving off a disagreeable odor which is nauseating to birds.

_Method_--In September, bring into the schoolroom and place in the terrarium, or breeding cage, a caraway or parsley plant on which these caterpillars are feeding, giving them fresh food day by day, and allow the pupils to observe them at recess and thus complete the lesson.

_The Caterpillar and Chrysalis._

_Observations_.--1. Touch the caterpillar on the head with a bit of grass. What does it do? What color are the horns? Where do they come from? Are there two separate horns or two branches of one horn? What odor comes from these horns? How does this protect the caterpillar? Does the caterpillar try to hide under the leaves when feeding? Is this evidence that it is not afraid of birds?

2. Describe the caterpillar as follows: What is its shape? Is it larger toward the head or the rear end? What is its ground color? How is it striped? How many black stripes? How many yellow spots in each black stripe? Are the yellow spots in the middle, or at each edge of the stripe?

3. How do the front three pairs of legs look? How do they compare with the prolegs? How many prop-legs are there? What is the color of the prolegs? How are they marked? Describe the prop-leg. What is its use?

4. Observe the caterpillar eating a leaf. How does it manage so as not to waste any?

5. Have you found the egg from which the caterpillar came? What color is it? Where is it laid?

6. How does the young caterpillar look? What are its colors? How many fleshy spines has it on each segment? Are these white on the white segments and black on the black segments? What is the color of the spines at their base?

Photo by M. V. Slingerland.]

7. Watch one of these caterpillars shed its skin. How does it prepare for this? How does it spin its carpet? Where does the silk come from? Describe how it acts when shedding its skin?

8. When a caterpillar is full grown, how does it hang itself up to change to a chrysalis? How does it make the silk button? How does it weave the loop or halter? How does it fasten it? When the halter is woven what does the caterpillar do with it? Describe how the last caterpillar skin is shed. How does the insect use its loop or halter while getting free from the molted skin?

9. Describe the chrysalis. What is its general shape? What is its color? Is it easily seen? Can you see where the wings are, within the chrysalis? How is the chrysalis supported?

10. How does the chrysalis look when the butterfly is about to emerge? Where does it break open? How does the butterfly look at first?

_The Butterfly_

1. Why is this butterfly called the black swallow-tail? What is the ground color of the wings? How many rows of yellow spots on the front wings? Are they all the same shape? How are they arranged between each two veins? Describe the hind wings. What colors are on them that are not on the front wings? Describe where this color is placed. Describe the eye-spot on the hind wing. Where is it? How do the markings on the lower side of the wing differ from those above? How does the ground color differ from the upper side?

2. What is the color of the body of the butterfly? Has it any marks? Has it the same number of legs as the Monarch? Describe its antennæ. Watch the butterfly getting nectar from the petunia blossom and describe the tongue. Where is the tongue when not in use?

3. How does the butterfly pass the winter? How does the mother butterfly differ in size and in markings from her mate?

* * * * *

“_The ‘caraway worms’ were the ones that revealed to us the
mystery of the pupa and butterfly. We saw one climb up the
side of a house, and watched it as with many slow, graceful
movements of the head, it wove for itself the loop of silk
which we called the ‘swing’ and which held it in place after
it changed to a chrysalis. We wondered why such a brilliant
caterpillar should change to such a dull-colored object,
almost the color of the clapboard against which it hung. Then,
one day, we found a damp, crumpled, black butterfly hanging to
the empty chrysalis skin, its wings ‘all mussed’ as we termed
it; and we gazed at it pityingly; but even as we gazed, the
crumpled wings expanded and then there came to our childish
minds a dim realization of the miracle wrought within that
little, dingy, empty shell._”
--HOW TO KNOW THE BUTTERFLIES, COMSTOCK.

THE MONARCH BUTTERFLY

_Teacher’s Story_

It is a great advantage to an insect to have the bird problem eliminated, and the monarch butterfly enjoys this advantage to the utmost. Its method of flight proclaims it, for it drifts about in a lazy, leisurely manner, its glowing red making it like a gleaming jewel in the air, a very different flight indeed from the zigzag dodging movements of other butterflies. The monarch has an interesting race history. It is a native of tropic America, and has probably learned through some race instinct, that by following its food plant north with the opening season, it gains immunity from special enemies other than birds, which attack it in some stage in its native haunts. Each mother butterfly follows the spring northward as it advances, as far as she finds the milkweed sprouted. There she deposits her eggs, from which hatch individuals which carry on the migration as far to the north as possible. It usually arrives in New York State early in July. As cold weather approaches, the monarchs often gather in large flocks and move back to the South. How they find their way we cannot understand, since there are among them none of the individuals which pressed northward early in the season.

The very brilliant copper-red color of the upper sides of the wings of the monarch is made even more brilliant by the contrasting black markings which outline the veins and border the wings, and also cover the tips of the front wings with a triangular patch; this latter seems to be an especially planned background for showing off the pale orange and white dots set within it. There are white dots set, two pairs in two rows, between each two veins in the black margin of the wings; and the fringe at the edge of the wings shows corresponding white markings. The hind wings and the front portions of the front wings have, on their lower sides, a ground color of pale yellow, which makes the insect less conspicuous when it alights and folds its wings above its back, upper surfaces together. The black veins, on the lower surface of the hind wings, are outlined with white, and the white spots are much larger than on the upper surface. The body is black, ornamented with a few pairs of white spots above and with many large white dots below. The chief distinguishing characteristic of insects, is the presence of six legs; but in this butterfly, the front legs are so small that they scarcely look like legs.

It is easy to observe the long, coiled tongue of the butterfly. If the act is done gently, the tongue may be uncoiled by lifting it out with a pin. To see a butterfly feeding upon nectar, is a very interesting process and may be observed in the garden almost any day. I have also observed it indoors, by bringing in petunias and nasturtiums for my imprisoned butterflies, but they are not so likely to eat when in confinement. The antennæ are about two-thirds as long as the body and each ends in a long knob; this knob, in some form, is what distinguishes the antennæ of the butterflies from those of moths. The male monarch has a black spot upon one of the veins of the hind wing; this is a perfume pocket and is filled with what are called scent scales; these are scales of peculiar shape which cover the wing at this place and give forth an odor, which we with our coarse sense of smell cannot perceive; but the lady monarch is attracted by this odor. The male monarch may be described to the children, as a dandy carrying a perfume pocket to attract his sweetheart.

Note the black band on the hind wings which distinguishes it from the monarch, which it imitates in color and markings.]

It is very interesting to the pupils if they are able to see a bit of the butterfly’s wing through a three-fourths objective; the covering of scales, arranged in such perfect rows, is very beautiful and also very wonderful. The children know that they get dust upon their fingers from butterflies’ wings, and they should know that each grain of this dust is an exquisite scale with notched edges and a ribbed surface.

The monarch is, for some reason unknown to us, distasteful to birds, and its brilliant colors are an advertisement to all birds of discretion, that here is an insect which tastes most disagreeably and that, therefore, should be left severely alone. There is another butterfly called the viceroy, which has taken advantage of this immunity from bird attack on the part of the monarch and has imitated its colors in a truly remarkable way, differing from it only in being smaller in size and having a black band across the middle of the hind wing. (See The Ways of the Six Footed, “A Sheep in Wolf’s Clothing”).

Photo by M. V. Slingerland.]

The milkweed caterpillar, which is the young of the monarch butterfly, is a striking object, and when fully grown is about two inches long. The milkweed is a succulent food and the caterpillar may mature in eleven days; it is a gay creature, with ground color of green and cross stripes of yellow and black. On top of the second segment, back of the head, are two long, slender whiplash-like organs, and on the seventh segment of the abdomen is a similar pair. When the caterpillar is frightened, the whiplashes at the front of the body twitch excitedly; when it walks, they move back and forth. Those at the rear of the body are more quiet and not so expressive of caterpillar emotions. These filaments are undoubtedly of use in frightening away the little parasitic flies, that lay their eggs upon the backs of caterpillars; these eggs hatch into little grubs that feed upon the internal fatty portions of the caterpillar and bring about its death through weakness. I remember well when I was a child, the creepy feeling with which I beheld these black and yellow-ringed caterpillars waving and lashing their whips back and forth after I had disturbed them; if the ichneumon flies were as frightened as I, the caterpillars were surely safe.

The caterpillar will feed upon no plant except milkweed; it feeds both day and night, with intervals of rest, and when resting, hides beneath the leaf. Its striking colors undoubtedly defend it from birds, because it is as distasteful to them as is the butterfly. However, when frightened, these caterpillars fall to the ground where their stripes make them very inconspicuous among the grass and thus perhaps save them from the attack of animals less fastidious than birds. These caterpillars, like all others, grow by shedding the skeleton skin as often as it becomes too tight.

A jewel of living jade and gold.]

The monarch chrysalis is, I maintain, the most beautiful gem in Nature’s jewel casket; it is an oblong jewel of jade, darker at the upper end and shading to the most exquisite whitish green below; outlining this lower paler portion are shining flecks of gold. If we look at these gold flecks with a lens, we cannot but believe that they are bits of polished gold-foil. There may be other gold dots also, and outlining the apex of the jewel, is a band of gold with a dotted lower edge of jet; and the knob at the top, to which the silk which suspends the chrysalis is fastened, is also jet. The chrysalis changes to a darker blue-green after two days, and black dots appear in the gold garniture. As this chrysalis is usually hung to the under side of a fence rail or overhanging rock, or to a leaf, it is usually surrounded by green vegetation, so that its green color protects it from prying eyes. Yet it is hardly from birds that it hides; perhaps its little gilt buttons are a hint to birds that this jewel is not palatable. As it nears the time for the butterfly to emerge, the chrysalis changes to a duller and darker hue. The butterfly emerges about twelve days after the change to a chrysalis.

_References_--Every Day Butterflies, Scudder; How to Know the Butterflies, Comstock; Moths and Butterflies, Dickerson; Ways of the Six Footed, Comstock; Moths and Butterflies, Ballard.

Photo by M. V. Slingerland.]

LESSON LXXI

THE MONARCH BUTTERFLY

_Leading thought_--The monarch butterfly migrates northward, every spring and summer, moving up as fast as milkweed appears, so as to give food to its caterpillar; and it has often been noticed migrating back southward in the autumn in large swarms. This insect is distasteful to birds in all its stages. Its chrysalis is one of the most beautiful objects in all nature.

_Method_--This lesson should be given in September, while yet the caterpillars of the monarch may be found feeding upon milkweed, and while there are yet many specimens of this gorgeous butterfly to be seen. The caterpillars may be brought in, on the food plant, and their habits and performances studied in the schoolroom; but care should be taken not to have the atmosphere too dry.

_The Butterfly_

_Observations_--1. How can you tell the monarch butterfly from all others? What part of the wings is red? What portions are black? What portions are white? What are the colors and markings on the lower side of the wings? What is the color of the body and how is it ornamented?

2. Is the flight of the monarch rapid or slow and leisurely? Is it a very showy insect when flying? Are its colors more brilliant in the sunshine when it is flying than at any other time? Why is it not afraid of birds?

3. When the butterfly alights, how does it hold its wings? Do you think it is as conspicuous when its wings are folded as when they are open?

4. Can you see the butterfly’s tongue? Describe the antennæ. How do they differ from the antennæ of moths? How many legs has this butterfly? How does this differ from other insects? Note if you can see any indications of front legs.

5. Is there on the butterfly you are studying, a black spot near one of the veins on each hind wing? Do you know what this is? What is it for?

6. Why are the striking colors of this butterfly a great advantage to it? Do you know of any other butterfly which imitates it and thus gains an advantage?

_The Monarch Caterpillar_

1. Where did you find the Monarch caterpillar? Was it feeding below or above on the leaves? Describe how it eats the milkweed leaf.

2. What are the colors and the markings of the caterpillar? Do you think these make it conspicuous?

3. How many whiplash shaped filaments do you find on the caterpillar? On which segments are they situated? Do these move when the caterpillar walks or when it is disturbed? Of what use are they to the caterpillar?

4. Do you think this caterpillar would feed upon anything except milkweed? Does it rest, when not feeding, upon the upper or the lower surface of the leaves? Does it feed during the night as well as the day?

5. If disturbed, what does the caterpillar do? When it falls down among the grass how do its cross stripes protect it from observation?

6. Tell all the interesting things which you have seen this caterpillar do.

_The Chrysalis_

1. When the caterpillar gets ready to change to a chrysalis what does it do? How does it hang up? Describe how it sheds its skin.

2. Describe the chrysalis. What is its color? How and where is it ornamented? Can you see, in the chrysalis, those parts which cover the wings of the future butterfly?

3. To what is the chrysalis attached? Is it in a position where it does not attract attention? How is it attached to the object?

4. After three or four days, how does the chrysalis change in color? Observe, if you can, the butterfly come out from the chrysalis, noting the following points: Where does the chrysalis skin open? How does the butterfly look when it first comes out? How does it act for the first two or three hours? How does the empty chrysalis skin look?

* * * * *

_A BUTTERFLY AT SEA_

_Far out at sea--the sun was high,
While veered the wind and flapped the sail;
We saw a snow-white butterfly
Dancing before the fitful gale
Far out at sea._

_The little wanderer, who had lost
His way, of danger nothing knew;
Settled a while upon the mast;
Then fluttered o’er the waters blue
Far out at sea._

_Above, there gleamed the boundless sky;
Beneath, the boundless ocean sheen;
Between them danced the butterfly,
The spirit-life of this fair scene,
Far out at sea._

_The tiny soul that soared away,
Seeking the clouds on fragile wings,
Lured by the brighter, purer ray
Which hope’s ecstatic morning brings--
Far out at sea._

_Away he sped, with shimmering glee,
Scarce seen, now lost, yet onward borne!
Night comes with wind and rain, and he
No more will dance before the morn,
Far out at sea._

_He dies, unlike his mates, I ween,
Perhaps not sooner or worse crossed;
And he hath felt and known and seen
A larger life and hope, though lost
Far out at sea._
--R. H. HORNE.

THE ISABELLA TIGER MOTH OR WOOLLY BEAR

_Teacher’s Story_

“_Brown and furry,
Caterpillar in a hurry,
Take your walk
To the shady leaf or stalk,
Or what not,
Which may be the chosen spot,
No toad spy you,
Hovering bird of prey pass by you;
Spin and die,
To live again a butterfly._”
--CHRISTINA ROSETTI.

Many times during autumn, the children find and bring in the very noticeable caterpillar which they call the “woolly bear.” It seems to them a companion of the road and the sunshine; it usually seems in a hurry, and if the children know that it is thus hastening to secure some safe place in which to hide during the season of cold and snow, they are far more interested in its future fate. If the caterpillar is already curled up for the winter, it will “come to” if warmed in the hand or in the sunshine.

The woolly bear is variable in appearance; sometimes there are five of the front segments black, four of the middle reddish brown, and three of the hind segments black. In others there are only four front segments black, six reddish ones, and two that are black at the end of the body; there are still other variations, so that each individual will tell its own story of color. There are really thirteen segments in this caterpillar, not counting the head; but the last two are so joined that probably the children will only count twelve. There are a regular number of tubercles on each side of each segment, and from each of these arises a little rosette of hairs; but the tubercles are packed so closely together, that it is difficult for the children to see how many rosettes there are on each side. While the body of the caterpillar looks as if it were covered with evenly clipped fur, there are usually a few longer hairs on the rear segment.

There is a pair of true legs on each of the three front segments which form the thorax, and there are four pairs of prolegs. All of the segments behind the front three, belong to the abdomen, and the prolegs are on the 3d, 4th, 5th and 6th abdominal segments; the prop-leg is at the rear end of the body. The true legs of this caterpillar have little claws, and are as shining as if encased in patent leather; but the prolegs and prop-leg are merely prolongations of the sides of the body to assist the insect in holding to the leaf. The yellow spot on either side of the first segment is a spiracle; this is an opening leading into the air tubes within the body, around which the blood flows and is thus purified. There are no spiracles on the second and third segments of the thorax, but eight of the abdominal segments have a spiracle on either side.

The woolly bear’s head is polished black; its antennæ are two tiny, yellow projections which can easily be seen with the naked eye. The eyes are too small to be thus seen; because of its minute eyes, the woolly bear cannot see very far and, therefore, it is obliged to feel its way. It does this by stretching out the front end of the body and reaching in every direction, to observe if there is anything to cling to in its neighborhood. When we try to seize the woolly bear, it rolls up in a little ball, and the hairs are so elastic that we take it up with great difficulty. These hairs are a protection from the attacks of birds which do not like bristles for food; and when the caterpillar is safely rolled up, the bird sees only a little bundle of bristles and lets it alone. The woolly bear feeds upon many plants, grass, clover, dandelion and others. It does not eat very much after we find it in autumn, because its growth is completed. The woolly bear should be kept in a box which should be placed out of doors, so that it may be protected from storms but have the ordinary winter temperature. Keeping it in a warm room during the winter often proves fatal.

Photo by M. V. Slingerland.]

Normally, the woolly bear does not make its cocoon until April or May. It finds some secluded spot in the fall, and there curls up in safety for the long winter nap; when the warm weather comes in the spring, it makes its cocoon by spinning silk about itself; in this silk are woven the hairs which it sheds easily at that time, and the whole cocoon seems made of felt. It seems amazing that such a large caterpillar can spin about itself and squeeze itself into such a small cocoon; and it is quite as amazing to see the smooth little pupa within the cocoon, in which is condensed all that was essential of the caterpillar. Sometimes when the caterpillars are kept in a warm room, they make their cocoons in the fall, but this is not natural.

Photo by M. V. Slingerland.]

The issuing of the moth from the cocoon is an interesting lesson for the last of May. The size of the moth which comes from the cocoon is quite comparable as a miracle with the size of the caterpillar that went into it. The moth is in color dull, grayish, tawny yellow with a few black dots on the wings; sometimes the hind wings are tinted with dull orange-red. On the middle of the back of the moth’s body there is a row of six black dots; and on each side of the body is a similar row. The legs are reddish above and tipped with black. The antennæ are small and inconspicuous. The moths are night fliers, and the mother moth seeks some plant on which to lay her eggs, that will be suitable food for the little caterpillar as soon as it is hatched.

_References_--Moths and Butterflies, Ballard.

Photo by M. V. Slingerland.]

LESSON LXXII

THE ISABELLA TIGER-MOTH, OR WOOLLY BEAR

_Leading thought_--When we see the woolly bear hurrying along in the fall, it is hunting for some cozy place in which to pass the winter. It makes its cocoon of silk woven with its own hair. In May, it comes forth a yellowish moth with black dots on its wings.

_Method_--Have the children bring in woolly bears as they find them, place them in boxes or breeding jars which have grass or clover growing in them. The children can handle the caterpillars while they are studying them, and then they should be put back into the breeding jars and be set out of doors where they can have natural conditions; thus the entire history may be studied.

_The Caterpillar_

_Observations_--1. How can you tell the woolly bear from all other caterpillars? Are they all colored alike? How many segments of the body are black at the front end? How many are red? How many segments are black at the rear end of the body? How many segments does this make in all?

2. Look closely at the hairs of the woolly bear. Are they set separately or in rosettes? Are any of the hairs of the body longer than others or are they all even?

3. Can you see, just back of the head, the true legs with their little sharp claws? How many are there?

4. Can you see the fleshy legs along the sides of the body? How many are there of these?

5. Can you see the prop-leg, or the hindmost leg of all? Of what use to the caterpillar are these fleshy legs?

6. Describe the woolly bear’s head. How does it act when eating?

7. Can you see a small, bright yellow spot on each side of the segment just behind the head? What do you suppose this is? Can you see little openings along each side of all the segments of the body, except the second and third? What are they? Describe how the woolly bear breathes.

8. On what does the woolly bear feed? If you can find a little woolly bear, give it fresh grass to eat and see how it grows. Why does it shed its skin?

9. When the woolly bear is hurrying along, does it lift its head and the front end of its body now and then? Why does it do this? Do you think it can see far?

10. What does the woolly bear do when you try to pick it up? Do you find you can pick it up easily? Do you think that these stiff hairs protect woolly bear from its enemies? What are its enemies?

11. Where should the woolly bear be kept in winter to make it comfortable?

_The Cocoon_

1. When does the woolly bear make its cocoon?

2. Of what material is it made? How does the woolly bear get into its cocoon?

3. What happens to it inside the cocoon?

4. Cut open a cocoon and describe how woolly bear looks now.

_The Moth_

1. Where did the moth come from?

2. How did it come out of the cocoon? See if you can find the empty pupa case in the cocoon.

3. What is the color of the moth and how is it marked? Are the front and hind wings the same color?

4. What are the markings and colors of the body? Of the legs?

5. What do you think that the Mother Isabella will do, if you give her liberty?

* * * * *

_The mute insect, fix’t upon the plant
On whose soft leaves it hangs, and from whose cup
Drains imperceptibly its nourishment,
Endear’d my wanderings._
--WORDSWORTH.

_Before your sight,
Mounts on the breeze the butterfly, and soars,
Small creature as she is, from earth’s bright flowers
Into the dewy clouds._
--WORDSWORTH.

Photo by M. V. Slingerland.]

THE CECROPIA

_Teacher’s Story_

The silk-worm which gives us the silk of commerce, has been domesticated for centuries in China. Because of this domestication, it is willing to be handled and is reared successfully in captivity, and has thus come to be the source of most of our silken fabrics. However, we have in America native silk-worms which produce a silk that is stronger and makes a more lustrous cloth than does that made from the Chinese species. But we have never had the time and the patience, here in America, to domesticate these giant silk-worms of ours, and so they are, as yet, of no commercial importance.

The names of our common native silk-worms are: The cecropia, promethea, polyphemus, and luna. In all of these species the moths are large and beautiful, attracting the attention of everyone who sees them. The caterpillars are rarely found, since their varied green colors render them inconspicuous among leaves on which they feed. None of the caterpillars of the giant silk-worms occur in sufficient numbers to injure the foliage of our trees to any extent; they simply help nature to do a little needful pruning. All of the moths are night flyers and are, therefore, seldom seen except by those who are interested in the visitors to our street lights.

The cecropia is the largest of our giant silk-worms, the wings of the moth expanding sometimes six and one-half inches. It occurs from the Atlantic Coast to the Rocky Mountains.

Photo by M. V. Slingerland.]

Photo by M. V. Slingerland.]

Photo by M. V. Slingerland.]

The cecropia cocoon is found most abundantly on our orchard and shade trees; it is called by the children the “cradle cocoon,” since it is shaped like a hammock and hung close below a branch, and it is a very safe shelter for the helpless creature within it. It is made of two walls of silk, the outer one being thick and paperlike and the inner one thin and firm; between these walls is a matting of loose silk, showing that the insect knows how to make a home that will protect it from winter weather. It is a clever builder in another respect, since at one end of the cocoon it spins the silk lengthwise instead of crosswise, thus making a valve through which the moth can push, when it issues in the spring. It is very interesting to watch one of these caterpillars spin its cocoon. It first makes a framework by stretching a few strands of silk, which it spins from a gland opening in the lower lip; it then makes a loose net-work upon the supporting strands, and then begins laying on the silk by moving its head back and forth, leaving the sticky thread in the shape of connecting M’s or of figure 8’s. Very industriously does it work, and after a short time it is so screened by the silk, that the rest of its performance remains to us a mystery. It is especially mysterious, since the inner wall of the cocoon encloses so small a cell that the caterpillar is obliged to compress itself in order to fit within it. This achievement would be something like that of a man who should build around himself a box only a few inches longer, wider and thicker than himself. After the cocoon is entirely finished, the caterpillar sheds its skin for the last time and changes into a pupa.

Very different, indeed, does the pupa look from the brilliant colored, warty caterpillar. It is compact, brown, oval and smooth, with ability to move but very little when disturbed. The cases which contain the wings, which are later to be the objects of our admiration, are now folded down like a tight cape around the body; and the antennæ, like great feathers, are outlined just in front of the wing cases. There is nothing more wonderful in all nature than the changes which are worked within one of these little, brown pupa cases; for within it, processes go on which change the creature from a crawler among the leaves to a winged inhabitant of the air. When we see how helpless this pupa is, we can understand better how much the strong silken cocoon is needed for protection from enemies, as well as from inclement weather.

Photo by M. V. Slingerland.]

In spring, usually in May, after the leaves are well out on the trees, the pupa skin is shed in its turn, and out of it comes the wet and wrinkled moth, its wings all crumpled, its furry, soft body very untidy; but it is only because of this soft and crumpled state that it is able to push its way out through the narrow door into the outer world. It has, on each side of its body just back of the head, two little horny hooks that help it to work its way out. It is certainly a sorry object as it issues, looking as if it had been dipped in water and had been squeezed in an inconsiderate hand. But the wet wings soon spread, the bright antennæ stretch out, the furry body becomes dry and fluffy, and the large moth appears in all its perfection. The ground color of the wings is a dusky, grayish brown while the outer margins are clay colored; the wings are crossed, beyond the middle, by a white band which has a broad outside margin of red. There is a red spot near the apex of the front wing, just outside of the zigzag white line; each wing bears, near its center, a crescent-shaped white spot bordered with red. But though it is so large, it does not need to eat; the caterpillar did all the eating that was necessary for the whole life of the insect; the mouth of the moth is not sufficiently perfected to take food.

Photo by M. V. Slingerland.]

Photo by M. V. Slingerland.]

When the cecropia caterpillar hatches from the egg, it is about a quarter of an inch long and is black; each segment is ornamented with six spiny tubercles. Like all other caterpillars, it has to grow by shedding its horny, skeleton skin, the soft skin beneath stretching to give more room at first, then finally hardening and being shed in its turn. This first molt of the cecropia caterpillar occurs about four days after it is hatched, and the caterpillar which issues looks quite different than it did before; it is now dull orange or yellow with black tubercles. After six or seven days more of feeding, the skin is again shed and now the caterpillar appears with a yellow body; the two tubercles on the top of each segment are now larger and more noticeable. They are blue on the first segment, large and orange-red on the second and third segments, and greenish blue with blackish spots and spines on all the other segments except the eleventh, which has on top, instead of a pair of tubercles, one large, yellow tubercle, ringed with black. The tubercles along the side of the insect are blue during this stage. The next molt occurs five or six days later; this time the caterpillar is bluish green in color, the large tubercles on the second and third segments being deep orange, those on the upper part of the other segments yellow, except those on the first and last segments, which are blue. All the other tubercles along the sides are blue. After the fourth molt it appears as an enormous caterpillar, often attaining the length of three inches, and is as large through as a man’s thumb; its colors are the same as in the preceding stage. There is some variation in the colors of the tubercles on the caterpillars during these different molts; in the third stage, it has been observed that the tubercles usually blue are sometimes black. After the last molt the caterpillar eats voraciously for perhaps two weeks or longer and then begins to spin its cocoon.

_References_--Moths and Butterflies, Ballard; Moths and Butterflies, Dickerson; Caterpillars and their Moths, Elliot and Soule.

Photo by M. V. Slingerland.]

LESSON LXXIII

THE CECROPIA

_Leading thought_--The cecropia moth passes the winter as a pupa in a cocoon which the caterpillar builds out of silk for the purpose. In the spring the moth issues and lays her eggs on some tree, the leaves of which the caterpillar relishes. The caterpillars are large and green with beautiful blue and orange tubercles.

_Method_--It is best to begin with the cocoons, for these are easily found after the leaves have fallen. These cocoons if kept in the schoolroom should be thoroughly wet at least once a week. However, it is better to keep them in a box out of doors where they can have the advantage of natural moisture and temperature; and from those that are kept outside the moths will not issue, until the leaves open upon the trees and provide food for the young caterpillars when the eggs hatch.

_The Cocoon_

_Observations_--1. How does the cocoon look on the outside? What is its general shape? To what is it fastened? Is it fastened to the lower or the upper side of a twig? Are there any dried leaves attached to it?

2. Where do you find cecropia cocoons? How do they look on the tree? Are they conspicuous?

3. Cut open the cocoon, being careful not to hurt the inmate. Can you see that it has an outer wall which is firm? What lies next to this? Describe the wall next to the pupa. How does this structure protect the pupa from changes of temperature and dampness?

4. Is the outside covering easy to tear? What birds are strong enough to tear this cocoon apart?

5. Are both ends of the cocoon alike? Do you find one end where the silk is not woven across but is placed lengthwise? Why is this so? Do you think that the moth can push out at this end better than at the other? Do you think the caterpillar, when it wove the cocoon, made it this way so that the moth could get out easily?

_The Pupa_

1. Take a pupa out of a cocoon carefully and place it on cotton in a wide-mouthed fruit jar where it may be observed. Can the pupa move at all? Is it unable to defend itself? Why does it not need to defend itself?

2. Can you see in the pupa the parts that will be the antennæ and the mouth?

3. Describe how the wing coverings look. Count the rings in the abdomen.

4. Why does the pupa need to be protected by a cocoon?

_The Moth_

1. What is the first sign which you discover that the moth is coming out of the cocoon? Can you hear the little scratching noise? What do you suppose makes it? How does the moth look when it first comes out? If it were not all soft and wet how could it come out from so small an opening?

2. Describe how the crumpled wings spread out and dry. How does the covering of the wings change in looks?

3. Make a water-color drawing or describe in detail the fully expanded moth, showing the color and markings of wings, body and antennæ.

4. Do the moths eat anything? Why do they not need to eat?

5. If one of the moths lays eggs, describe the eggs, noting color, size and the way they are placed.

_The Caterpillar_

1. On what do you find the cecropia caterpillar feeding? Describe its actions while feeding.

2. What is the color of the caterpillar? Describe how it is ornamented.

3. Can you see the breathing pores, or spiracles, along the sides of the body? How many of these on each segment? How do they help the caterpillar to breathe?

4. Describe the three pairs of true legs on the three segments just back of the head. Do these differ in form from the prolegs along the sides of the body? What is the special use of the prolegs? Describe the prop-leg which is the hindmost leg of all.

5. Do you know how many times the cecropia caterpillar sheds its skin while it is growing? Is it always the same color?

6. Watch the caterpillar spin its cocoon, describe how it begins and how it acts as long as you can see it. Where does the silk come from?

THE PROMETHEA

_Teacher’s Story_

The promethea is not so large as the cecropia, although the female resembles the latter somewhat. It is the most common of all our giant silk-worms. Its caterpillars feed upon wild cherry, lilac, ash, sassafras, buttonwood and many other forest trees.

During the winter, leaves may often be seen hanging straight down from the branches of wild cherry, lilac and ash. If these leaves are examined, they will be found to be wrapped around a silken case containing the pupa of the promethea. It is certainly a canny insect which hides itself during the winter in so good a disguise, that only the very wisest of birds ever suspect its presence. When the promethea caterpillar begins to spin, it selects a leaf and covers the upper side with silk, then it covers the petiole with silk, fastening it with a strong band to the twig, so that not even most violent winter winds will be able to tear it off. Then it draws the two edges of the leaf about itself like a cloak as far as it will reach, and inside this folded leaf it makes its cocoon, which always has an opening in the shape of a conical valve at the upper end, through which the moth may emerge in the spring. This caterpillar knows more botany than some people do, for it makes no mistake in distinguishing a compound leaf from a simple one. When it uses a leaflet of hickory for its cocoon, it fastens the leaflet to the mid stem of the leaf and then fastens the stem to the twig. The male pupa is much more slender than that of the female. The moths do not issue until May or June.

Note how the leaves are fastened by silk to the twigs.

Photo by M. V. Slingerland.]

The moth works its way out through the valve at the top of the cocoon. The female is a large, reddish brown moth with markings resembling somewhat those of the cecropia. The male is very different in appearance; its front wings have very graceful, prolonged tips, and both wings are almost black, bordered with ash color. The promethea moths differ somewhat in habit from the other silk-worms, in that they fly during the late afternoon as well as at night. The eggs are whitish with brown stain, and are laid in rows, a good many on the same leaf.

Photo by M. V. Slingerland.]