buttonholes, I was told if I did not set my stitches more closely
together, my buttonhole would look like a pig’s eye, a remark which
made me observant of that organ ever after. But though the pig’s eyes
are small, they certainly gleam with intelligence, and they take in
all that is going on, which may in any way affect his pigship.
The pig is the most intelligent of all the farm animals, if it is
only given a chance; it has excellent memory and can be taught tricks
readily; it is affectionate and will follow its master around like a
dog. Anyone who has seen a trained pig at a show picking out cards
and counting, must grant that it has brains, although we stuff it so
with fattening food, that it does not have a chance to use its brain,
except now and then when it breaks out of the sty and we try to drive
it back. Under these circumstances, we grant the pig all the sagacity
usually imputed to the one who once possessed swine and drove them
into the sea. Hunters of wild hogs proclaim that they are full of
strategy and cunning, and are exceedingly fierce. We pay tribute to
the pig’s cleverness when free to outwit us, when we say of other
uncertain undertakings, that they are like “buying a pig in a poke.”
The head of the wild hog is wedge-shaped with pointed snout, and this
form enables the animal to push into the thick underbrush along the
river banks, whenever it is attacked. But civilization has changed
this bold profile of the head, so that now in many breeds, there is
a hollow between the snout and eyes, giving the form which we call
“dished.” Some breeds have sharp, forward-opening ears, while others
have ears that lop. The wild pig of Europe and Asia has large, open
ears extending out wide and alert on each side of the head.
[Illustration: _Good for the pigs and good for the orchard._]
The covering of the pig is a thick skin beset with bristling hairs;
when the hog is excited, the bristles rise and add to the fury of
its appearance. The bristles aid in protecting the animal when it is
pushing through thorny thickets. The pig’s querly tail is merely an
ornament, although the tail of the wart hog of Africa, if pictures
may be relied upon, might be used in a limited fashion as a fly-brush.
When the pig is allowed to roam in the woods, it lives on roots,
nuts, and especially acorns and beech nuts; in the autumn it becomes
very fat through feeding upon the latter. The mast-fed bacon of the
semi-wild hogs of the Southern States is considered the best of all.
But almost anything animal or vegetable, that comes in its way, is
eaten by the hog, and it has been long noted that the hog has done
good service on our frontier as a killer of rattlesnakes. The pig is
well fitted for locomotion on either wet or dry soil, for the two
large hoofed toes enable it to walk well on dry ground and the two
hind toes, smaller and higher up, help to sustain it on marshy soil.
Although the pig’s legs are short, it is a swift runner unless it is
too fat. The razor-backs of the South are noted for their fleetness.
We understand somewhat the pig’s language; there is the constant
grunting, which is a sound that keeps the pig herd together. We
understand perfectly the complaining squeal of hunger, the satisfied
grunt signifying enjoyment of food, the squeal of terror when seized,
and the nasal growl when fighting. But there is much more to the
pig’s conversation than this; I know a certain lady, who is a lover
of animals, and who once undertook to talk pig language as best
she could imitate it, to two of her sows when they were engaged
in eating. They stopped eating, looked at each other a moment and
forthwith began fighting, each evidently attributing the lady’s
remark to the other, and obviously it was of an uncomplimentary
character.
The pig’s ability to take on fat was evidently a provision, in the
wild state, for storing up fat from mast that should help sustain the
animal during the hardships of winter; and this character is what
makes swine useful for our own food. Pigs, to do best, should be
allowed to have pasture and plenty of fresh green food. Their troughs
should be kept clean and they should have access to ashes, and above
all, they should have plenty of pure water; and as the pig does
not perspire freely, access to water where it can take its natural
mud-baths helps to keep the body cool and the pig healthy in hot
weather.
The breeds of hogs most common in America are the Berkshires, which
are black with white markings, and have ears extending erect; the
Poland Chinas, which are black and white with drooping ears; the
Duroc-Jersey, which are red or chestnut with drooping ears; the
Yorkshire and Cheshire, which are white with erect ears, while the
Cheshire White is white with drooping ears. The Poland China and
Duroc-Jersey are both pure American breeds.
_References_--Elementary Agriculture, Warren; Our Domestic Animals,
Burkett; The Country Reader, Buchanan; Lives of Animals, Ingersoll;
Types and Breeds of Farm Animals, Plumb; and the bulletins of the U.
S. Department of Agriculture.
LESSON LXIX
THE PIG
_Leading thought_--The pig is something more than a source of pork.
It is a sagacious animal and naturally cleanly in its habits when not
made prisoner by man.
_Method_--The questions in this lesson may be given to the pupils a
few at a time, and those who have access to farms or other places
where pigs are kept may make the observations and in giving them to
the class they should be discussed. Supplementary reading should
be given the pupils, which may inform them as to the habits and
peculiarities of the wild hogs. Theodore Roosevelt’s experience in
hunting the wart-hog in Africa will prove interesting reading.
[Illustration: _Bottle-fed babies._]
_Observations_--1. How does the pig’s nose differ from that of other
animals? What is it used for besides for smelling? Do you think the
pig’s sense of smell is very keen? Why do pigs root?
2. Describe the pig’s teeth. For what are they fitted? What are the
tushes for? Which way do the upper tushes turn? How do wild hogs use
their tushes?
3. Do you think that a pig’s eyes look intelligent? What color are
they? Do you think the pig can see well?
4. Is the pig’s head straight in front or is it dished? Is this
dished appearance ever found in wild hogs? Do the ears stand out
straight or are they lopped? What advantage is the wedge-shaped head
to the wild hogs?
5. How is the pig covered? Do you think the hair is thick enough to
keep off flies? Why does the pig wallow in the mud? Is it because the
animal is dirty by nature or because it is trying to keep clean? Do
the hog’s bristles stand up if it is angry?
6. If the pig could have its natural food what would it be and where
would it be found? Why and on what should pigs be pastured? What do
pigs find in the forest to eat? What kind of bacon is considered the
best?
7. On how many toes does the pig walk? Are there other toes on which
it does not walk? If wading in the mud are the two hind toes of use?
Do wild pigs run rapidly? Do tame pigs run rapidly if they are not
too fat? Do you think the pig can swim? Do you think that the pig’s
tail is of any use or merely an ornament?
8. What cries and noises do the pigs make which we can understand?
9. How do hogs fight each other? When the boars fight, how do they
attack or ward off the enemy? Where do we get the expression going
“sidewise like a hog to war?”
10. How many breeds of pigs do you know? Describe them.
11. What instances have you heard that show the hog’s intelligence?
12. Give an oral or written English exercise on one of the following
topics: “The antiquity of swine; how they were regarded by the
ancient Egyptians, Greeks and Romans;” (see encyclopedia). “The story
of hunting wild hogs in India;” “The razor-back hogs of the South;”
“The wart-hog of Africa.”
* * * * *
“_The nice little pig with a querly tail,
All soft as satin and pinky pale
Is a very different thing by far
Than the lumps of iniquity, big pigs are._”
--NONSENSE RHYME.
VI. INSECT STUDY
[Illustration: I]
Insects are among the most interesting and available of all living
creatures for nature-study. The lives of many of them afford more
interesting stories than are found in fairy lore; many of them
show exquisite colors and, more than all, they are small and are,
therefore, easily confined for observation.
While the young pupils should not be drilled in insect anatomy, as
if they were embryo zoologists, yet it is necessary for the teacher,
who would teach intelligently, to know something of the life stories,
habits and structure of the common insects. Generally speaking, all
insects develop from eggs. To most of us the word egg brings before
us the picture of the egg of the hen or of some other bird. But
insect eggs are often far more beautiful than those of any bird; they
are of widely differing forms, and are often exquisitely colored and
the shells may be ornately ribbed and pitted, sometimes adorned with
spines, and are as beautiful to look at through a microscope as the
most artistic piece of mosaic.
[Illustration: _The egg of the cotton moth, greatly enlarged._
From Manual for the Study of Insects.]
[Illustration: _The forest tent-caterpillar shedding its skin._
Photo by M. V. Slingerland.]
From the eggs, larvæ (_sing. larva_) issue. These larvæ may be
caterpillars, or the creatures commonly called worms, or may be
maggots or grubs. The larval stage is always devoted to feeding and
to growth. It is the chief business of the larva to eat diligently
and to attain maturity as soon as possible; for often the length of
the larval period depends more upon food than upon lapse of time. All
insects have their skeletons on the outside of the body; that is, the
outer covering of the body is chitinous, and the soft and inner parts
are attached to it and supported by it. This skin is so firm that
it cannot stretch to accommodate the increasing size of the growing
insect, thus from time to time it is shed. But before this is done,
a new skin is formed beneath the old one. After the old skin bursts
open and the insect crawls forth, the new skin is sufficiently soft
and elastic to allow for the increase in the size of the insect.
Soon, the new skin becomes hardened like the old one, and after a
time, is shed. This shedding of the skin is called molting. Some
insects shed their skins only four or five times during the period of
attaining their growth, while other species may molt twenty times or
more.
[Illustration: _Full-grown caterpillar of the luna moth._
Photo by M. V. Slingerland.]
After the larva has attained its full growth, it changes its skin
and its form, and becomes a pupa. The pupa stage is ordinarily one
of inaction, except that very wonderful changes take place within
the body itself. Usually the pupa has no power of moving around,
but in many cases it can squirm somewhat, if disturbed. The pupa of
the mosquito is active and is an exception to the rule. The pupa is
usually an oblong object and seems to be without head, feet or wings;
but if it is examined closely, especially in the case of butterflies
and moths, the antennæ, wings and legs may be seen, folded down
beneath the pupa skin.
[Illustration: _A luna cocoon cut open, showing the pupa._
Photo by M. V. Slingerland.]
Many larvæ, especially those of moths, weave about themselves a
covering of silk which serves to protect them from their enemies
and the weather, during the helpless pupa period. This silken
covering is called a cocoon. The larvæ of butterflies do not make a
silken cocoon, but the pupa is suspended to some object by a silken
knob, and in some cases by a halter of silk, and remains entirely
naked. The pupa of a butterfly is called a chrysalis. Care should
be taken to have the children use the words--pupa, chrysalis and
cocoon--understandingly.
[Illustration: _A butterfly chrysalis._]
[Illustration: _A luna moth._
_The delicate, exquisite green of the luna’s wings is set off
by the rose-purple, velvet border of the front and the white
fur on the body and inner edge of the hind wings. Little
wonder that it has been called the “Empress of the night”.
The long swallow tail of the hind wings give the moth a most
graceful shape, at the same time probably afford it protection
from observation. During the day time the moth hangs wings
down beneath the green leaves, and these long projections of
the hind wings folded together resemble a petiole, making the
insect look very much like a large leaf._
]
After a period varying from days to months, depending upon the
species of insect and the climate, the pupa skin bursts open and
from it emerges the adult insect, often equipped with large and
beautiful wings and always provided with six legs and a far more
complex structure of body than characterized it as a larva. The
insect never grows after it reaches this adult stage and, therefore,
never molts. Some people seem to believe that a small fly will grow
into a large fly, and a small beetle into a large beetle; but after
an insect attains its perfect wings, it does not grow larger. Many
adult insects take very little food, although some continue to eat
in order to support life. The adult stage is ordinarily shorter than
the larval stage; it seems a part of nature’s economic plan that
the grown-up insects should live only long enough to lay eggs, and
thus secure the continuation of the species. Insects having the four
distinct stages in their growth, egg, larva, pupa and adult, are said
to undergo complete metamorphosis.
But not all insects pass through an inactive pupa stage. With some
insects, like the grasshoppers, the young, as soon as they are
hatched, resemble the adult forms in appearance. These insects, like
the larvæ, shed their skins to accommodate their growth, but they
continue to feed and move about actively until the final molt when
the perfect insect appears. Such insects are said to have incomplete
metamorphosis, which simply means that the form of the body of the
adult insect is not greatly different from that of the young; the
dragon-flies, crickets, grasshoppers and bugs are of this type. The
young of insects with an incomplete metamorphosis are called nymphs
instead of larvæ.
[Illustration: _A young grasshopper, enlarged._
The line shows its actual length.]
[Illustration: _The adult of the same grasshopper, natural size._]
_Summary of the Metamorphoses of Insects_
_Kinds of Metamorphosis_ _Names of Stages_
⎧ Egg.
⎪ Larva.
I. Complete metamorphosis ⎨ Pupa. (The pupa is sometimes
⎪ enclosed in a cocoon.)
⎩ Adult or winged insect.
⎧ Egg
II. Incomplete metamorphosis ⎨ Nymph (several stages).
⎩ Adult, or imago.
[Illustration: _Insect brownies; tree-hoppers as seen through a
lens._]
THE STRUCTURE OF INSECTS
The insect body is made up of ring-like segments which are grown
together. These segments are divided into groups according to their
use and the organs which they bear. Thus the segments of an insect’s
body are grouped into three regions, the head, the thorax and the
abdomen. The head bears the eyes, the antennæ, and the mouth-parts.
On each side of the head of the adult insect may be seen the compound
eyes; these are so called, because they are made up of many small
eyes set together, much like the cells of the honeycomb. These
compound eyes are not found in larvæ. In addition to the compound
eyes, many adult insects possess simple eyes; these are placed
between the compound eyes and are usually three in number. Often they
cannot be seen without the aid of a lens.
[Illustration: _A part of the compound eye of an insect, enlarged._]
The antennæ or feelers are composed of many segments and are inserted
in front of the eyes or between them. They vary greatly in form. In
some insects they are mere threads; in others, like the silk-worm
moths, they are large, feather-like organs.
[Illustration: _Grasshopper, with the parts of the external anatomy
named._]
The mouth-parts of insects vary greatly in structure and in form,
being adapted to the life of the insect species to which they
minister. Some insects have jaws fitted for seizing their prey,
others for chewing leaves, others have a sucking tube for getting
the juices from plants or the blood from animals, and others long
delicate tubes for sipping the nectar from flowers.
[Illustration: _A sphinx moth with the sucking tongue unrolled._
Photo by M. V. Slingerland.]
In the biting insects, the mouth-parts consist of an upper lip, the
labrum, and under lip, the labium, and two pairs of jaws between
them. The upper pair of jaws is called the mandibles and the lower
pair, the maxillæ (_sing. maxilla_). There may be also within the
mouth, one or two tongue-like organs. Upon the maxillæ and upon the
lower lip there may also be feelers which are called palpi (_sing.
palpus_). The jaws of insects, when working, do not move up and down,
as do ours, but move sidewise like shears. In many of the insects,
the children are able to observe the mandibles and the palpi without
the aid of a lens.
[Illustration: _A tree-hopper, showing the mouth as a long,
three-jointed sucking tube, at_ a.]
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.
[Illustration: _The mouth-parts of a grasshopper dissected off,
enlarged and named._]
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.
[Illustration: _The sphinx caterpillar, with the parts of the
external anatomy named._]
_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_
[Illustration: T]
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.
[Illustration: _The eggs of the black swallow-tail butterfly,
enlarged._
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.
[Illustration: _Black swallow-tail caterpillars, showing two stages
of growth. The larger one has the scent organs protruded._
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.
[Illustration: _The chrysalis._
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?
[Illustration: _Black swallow-tail butterfly._
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?
[Illustration]
* * * * *
“_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_
[Illustration: I]
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.
[Illustration: _The monarch butterfly._]
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.
[Illustration: _The viceroy butterfly._
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.
[Illustration: _The scales on a butterfly’s wing, as seen through a
microscope._]
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”).
[Illustration: _The monarch caterpillar._
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.
[Illustration: _Monarch chrysalis._
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.
[Illustration: _The winter home of the viceroy caterpillar._]
_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.
[Illustration: _The male monarch butterfly, showing the scent pockets
on the hind wings._
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.
[Illustration: M]
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.
[Illustration: _Woolly bears._
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.
[Illustration: _The cocoon of the woolly bear._
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.
[Illustration: _The Isabella tiger-moths, the adults of the woolly
bear. The larger is the female._
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.
[Illustration: _The cecropia moth._
Photo by M. V. Slingerland.]
THE CECROPIA
_Teacher’s Story_
[Illustration: T]
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.
[Illustration: _The eggs of the cecropia moth._
Photo by M. V. Slingerland.]
[Illustration: _The cecropia caterpillar molting._
Photo by M. V. Slingerland.]
[Illustration: _Full-grown cecropia caterpillars._
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.
[Illustration: _Cecropia caterpillar weaving its cocoon._
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.
[Illustration: _A cecropia cocoon._
Photo by M. V. Slingerland.]
[Illustration: _The cecropia cocoon cut open, showing the pupa within
it._
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.
[Illustration: _Just out of the cocoon._
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_
[Illustration: T]
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.
[Illustration: _Promethea cocoons._
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.
[Illustration: _Promethea caterpillars._
Photo by M. V. Slingerland.]
The caterpillars, as they hatch from the eggs, have bodies ringed
with black and yellow. They are sociable little fellows and live
together side by side amicably, not exactly “toeing the mark” like
a spelling class, but all heads in a row at the edge of the leaf
where each is eating as fast as possible. When they are small, the
caterpillars remain on the under side of the leaves out of sight.
In about five days, the first skin is shed and the color of the
caterpillar remains about the same. Four or five days later, the
second molt occurs, and then the caterpillar appears in a beautiful
bluish green costume, with black tubercles, except four large ones
on the second and third segments, and one large one on the eleventh
segment, which are yellow. This caterpillar has an interesting habit
of weaving a carpet of silk on which to change its skin; it seems
to be better able to hold on while pushing off the old skin, if it
has the silken rug to cling to. After the third molt, the color is
a deeper greenish blue and the black tubercles are smaller, and
the five big ones are larger and bright orange in color. After the
fourth molt, which occurs after a period of about five or six days,
the caterpillar appears in its last stage. It is now over two inches
long, quite smooth and most prosperous looking. Its color is a
beautiful, light, greenish blue, and its head is yellow. It has six
rows of short, round, black tubercles. The four large tubercles at
the front end of the body are red, and the large tubercle on the rear
end of the body is yellow.
The cynthia is a beautiful moth which has come to us from Asia; it is
very large with a ground color of olive-green, with lavender tints
and white markings; there are white tufts of hairs on the abdomen.
It builds its cocoon like the promethea, fastening the petiole to the
twig, therefore the lesson indicated for the promethea will serve
as well for the cynthia. The cynthia caterpillars live upon the
ailanthus tree and are found only in the regions where this tree has
been introduced.
[Illustration: _The male promethea._
Photo by M. V. Slingerland.]
_References_--Moths and Butterflies, Dickerson; Caterpillars and
Their Moths, Elliot and Soule; Moths and Butterflies, Ballard.
[Illustration: _The female promethea._
Photo by M. V. Slingerland.]
LESSON LXXIV
THE PROMETHEA
_Leading thought_--The promethea caterpillar fastens a leaf to a twig
with silk and then makes its cocoon within this leaf. The male and
female moths are very different in appearance.
_Method_--This work should begin in the late fall, when the children
bring in these cocoons which they find dangling on the lilac bushes
or wild cherry trees. Much attention should be paid to the way the
leaf is fastened to the twig so it will not fall. The cocoons should
be kept out of doors, so that the moths will issue late in the spring
when they can have natural conditions for laying their eggs, and the
young caterpillars are supplied with plenty of food consisting of new
and tender leaves.
_The Cocoon_
_Observations_--1. On what tree did you find it? Does it look like
a cocoon? Does it not look like a dried leaf still clinging to the
tree? Do you think that this disguise keeps the birds from attacking
it? Do you know which birds are clever enough to see through this
disguise?
2. How is the leaf fastened to the twig? Could you pull it off
readily? What fastened the leaf to the twig?
3. Tear off the leaf and study the cocoon. Is there an opening to it?
At which end? What is this for?
4. Cut open a cocoon. Is it as thick as that of the cecropia?
5. Study the pupa. Is it as large as that of the cecropia?
6. Can you see where the antennæ of the moth are? Can you see the
wing covers? Can the pupa move?
_The Moth_
1. Are there two kinds of moths that come from the promethea cocoons?
Does one of them look something like the cecropia? This is the mother
promethea.
2. Are any of the moths almost black in color with wings bordered
with gray and with graceful prolonged tips to the front wings? This
is the father moth.
3. Make water color drawings of promethea moths, male and female.
4. If a promethea mother lays eggs, describe them.
_The Caterpillar_
1. How do the promethea caterpillars look when they first hatch from
the eggs? Do they stay together when they are very young? How do they
act? Where do they hide?
2. How do they change color as they grow older? Do they remain
together or scatter? Do they continue to hide on the lower sides of
leaves?
3. What preparation does a promethea caterpillar make before changing
its skin? Why does it shed its skin? Does its colors change with
every change of skin?
4. Describe the caterpillar when it is full-grown. What is its ground
color? What are the colors of its ornamental tubercles? The color of
its head?
5. Describe how a promethea caterpillar makes its cocoon.
THE HUMMINGBIRD, OR SPHINX, MOTHS
_Teacher’s Story_
[Illustration: I]
If during the early evening, when all the swift humming birds are
abed, we hear the whirr of rapidly moving wings and detect the blur
of them in the twilight, as if the creature carried by them hung
entranced before some deep-throated flower, and then whizzed away
like a bullet, we know that it was a hummingbird, or sphinx, moth.
And when we see a caterpillar with a horn on the wrong end of the
body, a caterpillar which, when disturbed, rears threateningly, then
we may know it is the sphinx larva. And when we find a strange, brown
segmented shell, with a long jug handle at one side, buried in the
earth as we spade up the garden in the spring, then we know we have
the sphinx pupa.
The sphinx was a vaudeville person of ancient mythology who went
about boring people by asking them riddles; and, if they could
not give the right answers, very promptly ate them up. Although
Linnaeus gave the name of sphinx to these moths, because he fancied
he saw a resemblance in the resting or threatening attitude of the
larvæ to the Egyptian Sphinx, there are still other resemblances.
These insects present three riddles: The first one is, “Am I a
humming-bird?” the second, “Why do I wear a horn or an eye-spot on
the rear end of my body where horns and eyes are surely useless?” and
the third, “Why do I look like a jug with a handle and no spout?”
[Illustration: _Sphinx larva in sphinx attitude._
From Manual for the Study of Insects.]
The sphinx moths are beautiful and elegant creatures. They have a
distinctly tailor-made appearance, their colors are so genteel and
“the cut” so perfect. They have long, rather narrow, strong wings
which enable them to fly with extraordinary rapidity. The hind wings
are shorter, but act as one with the front wings. The body is stout
and spindle-shaped. The antennæ are thickened in the middle or toward
the tip, and in many species have the tip recurved into a hook.
Their colors show most harmonious combinations and most exquisite
contrasts; the pattern, although often complex, shows perfect
refinement. Olive, tan, brown and ochre, black and yellow, and the
whole gamut of greys, with eye-spots or bands athwart the hind wings
of rose color or crimson, are some of the sphinx color schemes.
[Illustration: _The tobacco sphinx moth with tongue extended._
Photo by M. V. Slingerland.]
Most of the sphinx moths have remarkable long tongues, being
sometimes twice the length of the body. When not in use, the tongue
is curled like a watch spring in front and beneath the head; but of
what possible use is such a long tongue! That is a story for certain
flowers to tell, the flowers which have the nectar wells far down at
the base of tubular corollas, like the petunia, the morning glory
or the nasturtium; such flowers were evidently developed to match
the long-tongued insects. Some of these flowers, like the jimson
weed and nicotina, open late in the day so as to be ready for these
evening visitors. In some cases, especially in the orchids, there is
a special partnership established between one species of flower and
one species of sphinx moths. The tobacco sphinx is an instance of
such partnership; this moth visits tobacco flowers and helps develop
the seeds by carrying pollen from flower to flower; and in turn it
lays its eggs upon the leaves of this plant, on which its great
caterpillar feeds and waxes fat, and in high dudgeon often disputes
the smoker’s sole right to the “weed.” Tobacco probably receives
enough benefit from the ministrations of the moth to compensate
for the injury it suffers from the caterpillars; but the owner of
the tobacco field, not being a plant, does not look at it in this
equitable manner.
[Illustration: _The moth of the sphinx caterpillar, which feeds on tomato._
Photo by M. V. Slingerland.]
The sphinx caterpillars are leaf eaters and each species feeds upon
a limited number of plants which are usually related; for instance,
one feeds upon both the potato and tomato; another upon the Virginia
creeper and grapes. In color these caterpillars so resemble the
leaves that they are discovered with difficulty. Those on the
Virginia creeper, which shades porches, may be located by the black
pellets of waste material which fall from them to the ground; but
even after this unmistakable hint I have searched a long time to find
the caterpillar in the leaves above; its color serves to hide the
insect from birds which feed upon it eagerly. In some species, the
caterpillars are ornamented with oblique stripes along the sides,
and in others the stripes are lengthwise. There is often a great
variation in color between the caterpillars of the same species; the
tomato worm is sometimes green and sometimes black.
[Illustration: _The pupa of the common tomato sphinx caterpillar._
Note that the part encasing the long tongue is free and looks like
the handle of a jug.
Photo by M. V. Slingerland.]
The horn on the rear end is often in the young larva of different
color than the body; in some species it stands straight up and in
some it is curled toward the back. It is an absolutely harmless
projection and does not sting nor is it poisonous. However, it
looks awe-inspiring and perhaps protects its owner in that way. The
_Pandora_ sphinx has its horn curled over its back in the young
stage but when fully grown the horn is shed; in its place is an
eye-spot which, if seen between the leaves, is enough to frighten
away any cautious bird fearing the evil eye of serpents. The sphinx
caterpillars have a habit, when disturbed or when resting, of rearing
up the front part of the body, telescoping the head back into the
thoracic segments, which in most species are enlarged, and assuming
a most threatening and ferocious aspect. If attacked they will swing
sidewise, this way and then that, making a fierce crackling sound
meanwhile, well calculated to fill the trespasser with terror.
When resting they often remain in this lifted attitude for hours,
absolutely rigid.
[Illustration: _Tailor-made moth, the adult of the Myron sphinx._]
The six true legs are short with sharp, little claws. There are four
pairs of fleshy prolegs, each foot being armed with hooks for holding
on to leaf or twig; and the large, fleshy prop-leg on the rear
segment is able to clasp a twig like a vise. All these fleshy legs
are used for holding on, while the true legs are used for holding the
edges of the leaf where the sidewise working jaws can cut it freely.
These caterpillars do clean work, leaving only the harder and more
woody ribs of the leaves. The myron caterpillar seems to go out of
its way to cut off the stems of both the grape and Virginia creeper.
There are nine pairs of spiracles, a pair on each segment of the
abdomen and on the first thoracic segment. The edges of these air
openings are often strikingly colored. Through the spiracles the air
is admitted into all the breathing tubes of the body around which the
blood flows and is purified; no insect breathes through its mouth.
These caterpillars, like all others, grow by shedding the skeleton
skin, which splits down the back.
[Illustration: _The eggs of the Myron sphinx._
Photo by M. V. Slingerland.]
Often one of these caterpillars is seen covered with white objects
which the ignorant, who do not know that caterpillars never lay
eggs, have called, eggs. But the sphinx moths at any stage would
have horror of such eggs as these! They are not eggs but are little
silken cocoons spun by the larvæ of a hymenopterous parasite. It is a
tiny, four-winged “fly” which lays its eggs within the caterpillar.
The little grubs which hatch from these eggs feed upon the fleshy
portions of the caterpillar until they get their growth, at which
time the poor caterpillar is almost exhausted; and then they have the
impudence to come out and spin their silken cocoons and fasten them
to the back of their victim. Later, they cut a little lid to their
silken cells which they lift up as they come out into the world to
search for more caterpillars.
[Illustration: _A full-grown caterpillar of the Myron sphinx._]
As soon as the sphinx larva has obtained its growth, it descends and
burrows into the earth. It does not spin any cocoon but packs the
soil into a smooth-walled cell in which it changes to a pupa. In the
spring the pupa works its way to the surface of the ground and the
moth issues. In the case of the tomato and tobacco sphinx pupa, the
enormously long tongue has its case separate from the body of the
pupa, which makes the “jug handle.” The wing cases and the antennæ
cases can be distinctly seen. In the case of the other species the
pupæ have the tongue case fast to the body. The larva of the myron
sphinx does not enter the ground, but draws a few leaves about it on
the surface of the ground, fastens them with silk and there changes
to a pupa.
_References_--Caterpillars and their Moths, Elliot and Soule; Moths
and Butterflies, Dickerson; Moths and Butterflies, Ballard; Manual
for the Study of Insects, Comstock.
[Illustration: _A “cake walk.” The caterpillars of the Myron sphinx
in attitude of defence._
Photo by M. V. Slingerland.]
LESSON LXXV
THE HUMMING-BIRD, OR SPHINX, MOTHS
_Leading thought_--The sphinx caterpillars have a slender horn or
eye-spot on the last segment of the body. When disturbed or when
resting they rear the front part of the body in a threatening
attitude. They spin no cocoons but change to pupæ in the ground.
The adults are called humming-bird moths, because of their swift
and purring flight. Many flowers depend upon the sphinx moths for
carrying their pollen.
_Method_--The sphinx caterpillar found on the potato or tobacco, or
one of the species feeding upon the Virginia creeper is in September
available in almost any locality for this lesson. The caterpillars
should be placed in a breeding cage in the schoolroom. Fresh food
should be given them every day and moist earth be placed in the
bottom of the cages. It is useless for the amateur to try to rear the
adults from the pupæ in breeding cages. The moths may be caught in
nets during the evening when they are hovering over the petunia beds.
These may be placed on leaves in a tumbler or jar for observation.
_The Caterpillar_
_Observations_--1. On what plant is it feeding? What is its general
color? Is it striped? What colors in the stripes? Are they oblique or
lengthwise stripes? Are all the caterpillars the same color?
[Illustration: _The pupæ of the Myron sphinx within the cocoons._
Photo by M. V. Slingerland.]
2. Can you find the caterpillar easily when feeding? Why is it not
conspicuous when on the plant? Of what use is this to the caterpillar?
3. Note the horn on the end of the caterpillar. Is it straight or
curled? Is it on the head end? What color is it? Do you think it is
of any use to the caterpillar? Do you think it is a sting? If there
is no horn, is there an eye-spot on the last segment? What color is
it? Can you think of any way in which this eye-spot protects the
caterpillar?
4. Which segments of the caterpillar are the largest? When the
creature is disturbed what position does it assume? How does it move?
What noise does it make? Do you think this attitude scares away
enemies? What position does it assume when resting? Do you think that
it resembles the Egyptian Sphinx when resting?
5. How many true legs has this caterpillar? How does it use them when
feeding? How many prolegs has it? How are these fleshy legs used? How
are they armed to hold fast to the leaf or twig? Describe the hind or
prop-leg. How is it used?
[Illustration:
_A Myron caterpillar that has been parasitized. The white
objects upon it are the cocoons of the little grubs which feed
upon the fatty parts of the caterpillar._
Photo by M. V. Slingerland.]
6. Do you see the breathing pores or spiracles along the sides of
the body? How many are there? How are they colored? How does the
caterpillar breathe? Do you think it can breathe through its mouth?
7. How does the sphinx caterpillar grow? Watch your caterpillar and
see it shed its skin. Where does the old skin break open? How does
the new, soft skin look? Do the young caterpillars resemble the
full-grown ones?
8. Describe how the caterpillar eats. Can you see the jaws move? Does
it eat up the plant clean as it goes?
9. Have you ever found the sphinx caterpillar covered with whitish,
oval objects? What are these? Does the caterpillar look plump or
emaciated? Explain what these objects are and how they came to be
there.
10. Where does the caterpillar go to change to a pupa? Does it make
cocoons? How does the pupa look? Can you see the long tongue case,
the wing cases, the antennæ cases?
_The Moth_
1. Where did you find this moth? Was it flying by daylight or in the
dusk? How did its swift moving wings sound? Was it visiting flowers?
What flowers? Where is the nectar in these flowers?
2. What is the shape of the moth’s body? Is it stout or slender? What
colors has it? How is it marked?
3. The wings of which pair are longer? Sketch or describe the form of
the front and the hind wings? Are the outer edges scalloped, notched
or even? What colors are on the front wing? On the hind one? Are
these colors harmonious and beautiful? Make a sketch of the moth in
water-color.
[Illustration: _The moths of the Myron sphinx on Virginia creeper._
Photo by M. V. Slingerland.]
4. What is the shape of the antennæ? Describe the eyes. Can you see
the coiled tongue? Uncoil it with a pin and note how long it is. Why
does this moth need such a long tongue?
5. From what flowers do the sphinx moths get nectar? How does the
moth support itself when probing for nectar? Do you know any flowers
which are dependent on the sphinx moths for carrying their pollen?
How many kinds of sphinx moths do you know?
[Illustration: _The white-lined sphinx moth._]
* * * * *
_Hurt no living thing:
Ladybird, nor butterfly,
Nor moth with dusty wing,
Nor cricket chirping cheerily,
Nor grasshopper so light of leap,
Nor dancing gnat, nor beetle fat,
Nor harmless worms that creep._
--CHRISTINA ROSSETTI.
THE CODLING MOTH
_Teacher’s Story_
[Illustration: I]
It is difficult to decide which seems the most disturbed, the person
who bites into an apple and uncovers a worm, or the worm which is
uncovered. From our standpoint, there is nothing attractive about
the worm which destroys the beauty and appetizing qualities of our
fruit, but from the insect standpoint the codling caterpillar (which
is not a worm at all), is not at all bad. When full-grown, it is
about three-fourths of an inch long, and is likely to be flesh color,
or even rose color, with brownish head; as a young larva, it has a
number of darker rose spots on each segment and is whitish in color;
the shield on the first segment behind the head, and that on the
last segment of the body, are black. When full-grown, the apple worm
is plump and lively; and while jerking angrily at being disturbed,
we can see its true legs, one pair to each of the three segments of
the body behind the head. These true legs have sharp, single claws.
Behind these the third, fourth, fifth and sixth segments of the
abdomen are each furnished with a pair of fleshy prolegs and the hind
segment has a prop-leg. These fleshy legs are mere makeshifts on the
part of the caterpillar for carrying the long body; since the three
pairs of front legs are the ones from which develop the legs of the
moth. The noticing of the legs of the codling moth is an important
observation on the part of the pupils, since, by their presence, this
insect may be distinguished from the young of the plum curculio,
which is also found in apples but which is legless. The codling moth
has twelve segments in the body, back of the head.
The codling larva usually enters the apple at the blossom end and
tunnels down by the side of the core until it reaches the middle,
before making its way out into the pulp. The larva weaves a web as it
goes, but this is probably incidental, since many caterpillars spin
silk as they go, “street yarn” our grandmothers might have called it.
In this web are entangled the pellets of indigestible matter, making
a very unsavory looking mass. The place of exit is usually circular,
large enough to accommodate the body of the larva, and it leads out
from a tunnel which may be a half inch or more in diameter beneath
the rind. Often the larva makes the door sometime before it is ready
to leave the apple, and plugs it with a mass of debris, fastened
together with the silk. As it leaves the apple, the remnants of this
plug may be seen streaming out of the opening. Often also, there is a
mass of waste pellets pushed out by the young larva from its burrow,
as it enters the apple; thus it injures the appearance of the apple,
at both entrance and exit. If the apple has not received infection by
lying next to another rotting apple, it first begins to rot around
the burrow of the worm, especially near the place of exit.
The codling caterpillar injures the fruit in the following ways:
The apples are likely to be stunted and fall early; the apples rot
about the injured places and thus cannot be stored successfully; the
apples thus injured look unattractive and, therefore, their market
value is lessened; wormy apples, packed in barrels with others,
rot and contaminate all the neighboring apples. This insect also
attacks pears and sometimes peaches. It has been carefully estimated
that every year the codling moth does three million dollars worth of
injury to the apple and pear crops in New York State. Think of paying
three million dollars a year for the sake of having wormy apples!
[Illustration: _A wormy apple._
Photo by M. V. Slingerland.]
The larvæ usually leave the apples before winter. If the apples have
fallen, they crawl up the tree and there make their cocoons beneath
the loose bark; but if they leave the apples while they are on the
trees, they spin silk and swing down. If carried into the storeroom
or placed in barrels, they seek quarters in protected crevices. In
fact, while they particularly like the loose bark of the apple trees,
they are likely to build their cocoons on nearby fences or on brush,
wherever they can find the needed protection. The cocoon is made of
fine but rather rough silk which is spun from a gland opening near
the mouth of the caterpillar; the cocoon is not beautiful although
it is smooth inside. It is usually spun between a loose bit of bark
and the body of the tree; but after making it, the insect seems
in no hurry to change its condition and remains a quite lively
caterpillar until spring. It is while the codling larvæ are in their
winter quarters that our bird friends of the winter, the nuthatches,
woodpeckers and chickadees, destroy them in great numbers, hunting
eagerly for them in every crevice of the trees. It is therefore good
policy for us to coax these birds to our orchards by placing beef fat
on the branches and thus entice these little caterpillar hunters to
visit the trees every day.
It is an interesting fact that the codling caterpillars, which make
cocoons before August first, change immediately to pupæ which soon
change to moths, and thus another generation gets in its work before
the apples are harvested.
[Illustration: _The larva of the codling moth, much enlarged._
Photomicrograph by M. V. Slingerland.]
The codling moth is a beautiful little creature with delicate antennæ
and a brown, mottled and banded body; its wings are graced by wavy
bands of ashy and brown lines, and the tips of the front wings are
dark brown with a pattern of gold bronze wrought into them; the hind
wings are shiny brown with darker edges and little fringes. The moths
issue in the spring and lay their eggs on the young apples just after
the petals fall. The egg looks like a minute drop of dried milk and
is laid on the side of the bud; but the little larva, soon after it
is hatched, crawls to the blossom and finds entrance there; and it
is therefore important that its first lunch should include a bit of
arsenic and thus end its career before it fairly begins. The trees
should be sprayed with some arsenical poison directly after the
petals fall, and before the five lobes of the calyx close up around
the stamens. If the trees are sprayed while blossoming, the pollen
is washed away and the apples do not set; moreover, the bees which
help us much in carrying pollen are killed. If the trees are sprayed
directly after the calyx closes up around the stamens the poison does
not lodge at the base of the stamens and the little rascals get into
the apples without getting a dose. (See Lesson on the Apple).
[Illustration: _The pupæ and cocoons of the codling moths._
Photo by M. V. Slingerland.]
LESSON LXXVI
THE CODLING MOTH
_Leading thought_--The codling moth is a tiny brown moth with bronze
markings which lays its egg on the apple. The larva hatching from
the egg enters the blossom end and feeds upon the pulp of the apple,
injuring it greatly. After attaining its growth it leaves the apple
and hides beneath the bark of the tree or in other protected places,
and in the spring makes the cocoon from which the moth issues in time
to lay eggs upon the young apples.
[Illustration:
_The adult of the codling moth, showing the variations of its
markings. The two larger are twice natural size._
Photo by M. V. Slingerland.
]
[Illustration: _Just ready to spray. A pear and two apples from which
the petals have recently fallen and with calyx lobes widely spread._
Photo by M. V. Slingerland.]
_Method_--The lesson should begin with a study of wormy apples,
preferably in the fall when the worms are still within their burrows.
After the pupils become familiar with the appearance of the insect
and its methods of work, a prize of some sort might be offered for
the one who will bring to school the greatest number of hibernating
larvæ found in their winter quarters. Place these larvæ in a box with
cheese-cloth tacked over its open side; place this box out of doors
in a protected position. Examine the cocoons to find the pupæ about
the last of April; after the pupæ appear, look for the moths in about
five days.
It would be a very good idea for the pupils to prepare a Riker mount
showing specimens of the moths, of the cocoons showing the cast
pupa skin, and of the caterpillar in a homeopathic vial of alcohol;
pictures illustrating the work of the insect may be added. The
pictures should be drawn by the pupils, showing the wormy apple, both
the outside and in section. The pupils can also sketch, from the
pictures here given, the young apple when just in the right condition
to spray, with a note explaining why.
_Observations_--1. Find an apple with a codling moth larva in it. How
large is the worm? How does it act when disturbed?
2. What is the color of the caterpillar’s body? Its head?
3. How many segments are there in the body? How many of these bear
legs? What is the difference in form between the three front pairs of
legs and the others?
4. Look at a wormy apple. How can you tell it is wormy from the
outside? Can you see where the worm entered the apple? Was the burrow
large or small at first? Can you find an apple with a worm in it
which has the door for exit made, but closed with waste matter? How
is this matter fastened together? If the apple has no worm in it,
can you see where it left the apple? Make a sketch or describe the
evidence of the caterpillar’s progress through the apple. Do you find
a web of silk in the wormy part? Why is this? Does the worm eat the
seeds as well as the pulp of the apple?
5. Take a dozen rotting apples, how many of them are wormy? Do the
parts of the apple injured by the worm begin to rot first? In how
many ways does the codling moth injure the apple? Does it injure
other fruits than apples?
6. How late in the fall do you find the codling larvæ in the apple?
Where do these larvæ go when they leave the apple?
_Work to be done in March or early April_--Visit an orchard and look
under the loose bark on old trees, or along protected sections of
fences or brush piles and bring in all the cocoons you can find. Do
not injure the cocoons by tearing them from the places where they are
woven, but bring them in on bits of the bark or other material to
which they are attached.
1. How does the cocoon look outside and inside? What is in the
cocoon? Why was the cocoon made? When was it made?
2. Place the cocoons in a box covered with cheese-cloth and place the
box out of doors where the contents can be frequently observed and
make the following notes:
3. When does the larva change to the pupa? Describe the pupa. How
does the cocoon look after the moth issues from it?
4. Describe the moth, noting color of head, thorax, body, front and
hind wings?
5. If these moths were free to fly around the orchard, when and where
would they lay their eggs?
6. When should the trees be sprayed to kill the young codling moth?
With what should they be sprayed? Why should they not be sprayed
during the blossoming period? Why not after the calyx closes?
[Illustration: _Almost too late to spray. The apples on each side
have the calyx lobes nearly drawn together. The pear in the middle
still has the calyx cavity open._
Photo by M. V. Slingerland.]
7. How do the nuthatches, downy woodpeckers and chickadees help us in
getting rid of the codling moth?
8. Write an essay on the life history of the codling moth, the damage
done by it, and the best methods of keeping it in check.
_References_--The following bulletins from the U. S. Dept, of
Agriculture: Farmers’ Bulletin 247, “The Control of the Codling Moth
and Apple Scab;” Bulletin 35, New Series, Bureau of Entomology,
“Report on the Codling Moth Investigations,” price 10 cents; Bulletin
41, “The Codling Moth,” 105 pages, 15 cents, by Special Field Agent,
C. B. Simpson; Bulletin 68, Part VII, “Demonstration Spraying for
the Codling Moth,” price 5 cents. The Spraying of Plants, Lodeman,
Macmillan Company; Economic Entomology, Smith.
LEAF-MINERS
_Teacher’s Story_
“_And there’s never a leaf nor a blade too mean
To be some happy creature’s palace_.”
--LOWELL.
[Illustration: M]
May not Lowell have had in mind, when he wrote these lines, the canny
little creatures which find sustenance for their complete growth
between the upper and lower surfaces of a leaf, which seems to us as
thin as a sheet of paper. To most children, it seems quite incredible
that there is anything between the upper and lower surfaces of a
leaf, and this lesson should hinge on the fact that in every leaf,
however thin, there are rows of cells containing the living substance
of the leaf, with a wall above and a wall below to protect them. Some
of the smaller insects have discovered this hidden treasure, which
they mine while safely protected from sight, and thus make strange
figures upon the leaves.
[Illustration: _Serpentine mines in nasturtium leaf._]
[Illustration: _Serpentine mines in leaf of columbine._
Comstock’s Manual.]
Among the most familiar of these are the serpentine mines, so called
because the figure formed by the eating out of the green pulp of the
leaf, curves like a serpent. These mines are made by the caterpillars
of tiny moths, which have long fringes upon the hind wings. The life
story of such a moth is as follows: The little moth, whose expanded
wings measure scarcely a quarter of an inch across, lays an egg on
the leaf; from this, there hatches a tiny caterpillar that soon eats
its way into the midst of the leaf. In shape, the caterpillar is
somewhat “square built,” being rather stocky and wide for its length;
it feeds upon the juicy tissues of the leaf and divides, as it goes,
the upper from the lower surface of the leaf; and it teaches us,
if we choose to look, that these outer walls of the leaf are thin,
colorless, and paper-like. We can trace the whole life history and
wanderings of the little creature, from the time when, as small as a
pin point, it began to feed, until it attained its full growth. As
it increased in size, its appetite grew larger also, and these two
forces working together naturally enlarged its house. When finally
the little miner gets its growth, it makes a rather larger and more
commodious room at the end of its mine, which to us looks like
the head of the serpent; here it changes to a pupa, perhaps after
nibbling a hole with its sharp little jaws, so that when it changes
to a soft, fluffy little moth with mouth unfitted for biting, it is
able to escape. In some species, the caterpillar comes out of the
mine and goes into the ground to change to a pupa. By holding up to
the light a leaf thus mined, we can see why this little chap was
never obliged to clean house; it mined out a new room every day,
and left the sweepings in the abandoned mine behind. Mines of this
sort are often seen on the leaves of nasturtium, the smooth pigweed,
columbine, and many other plants. There are mines of many shapes,
each form being made by a different species of insect. Some flare
suddenly from a point and are trumpet-shaped while some are mere
blotches. The blotch mines are made, through the habits of the insect
within them; it feeds around and around, instead of forging ahead, as
is the case with the serpentine miners. The larvæ of beetles, flies
and moths may mine leaves, each species having its own special food
plant. Most of the smaller leaf mines are made by the caterpillars
of the moths, which are fitly called the Tineina or Tineids. Most of
these barely have a wing expanse that will reach a quarter of an inch
and many are much smaller; they all have narrow wings, the hind wings
being mere threads bordered with beautiful fringes. The specific
names of these moths usually end in “ella;” thus, the one that mines
in apple is _malifoliella_, the one in grain is _granella_. One of
these little moths, _Gelechia pinifoliella_ lives the whole of its
growing life in half of a pine needle. The moth lays the egg at about
the middle of the needle, and the little caterpillar that hatches
from it, gnaws its way directly into the heart of the needle; and
there, as snug as snug can be, it lives and feeds until it is almost
a quarter of an inch long, think of it! Many a time I have held up
to the light a pine needle thus inhabited, and have seen the little
miner race up and down its abode as if it knew that something was
happening. When it finally attains its growth it makes wider the
little door, through which it entered; it does this very neatly, the
door is an even oval, and looks as if it were made with the use of
dividers. After thus opening the door, the caterpillar changes to
a little, long pupa, very close to its exit; and later it emerges,
as an exquisite little moth with silvery bands on its narrow, brown
wings, and a luxurious fringe on the edges of its narrow, hind wings
and also on the outer hind edges of the front wings.
[Illustration: _Trumpet mines in leaf of apple._
Photo by M. V. Slingerland.]
[Illustration:
_The pine-needle leaf-miner. The mined leaves of pine natural
size. The caterpillar, pupa and moth of the leaf miner much
enlarged. The lines show actual size of insect._
Comstock’s Manual.]
The gross mines in the leaves of dock and beet are not pretty. The
poor leaves are slitted, sometimes for their whole length, and soon
turn brown and lie prone on the ground, or dangle pathetically from
the stalk. These mines are made by the larvæ of a fly, and a whole
family live in the same habitation. If we hold a leaf thus mined up
to the light, while it is still green, we can see several of the
larvæ working, each making a bag in the life substance of the leaf,
and yet all joining together to make a great blister. The flies
that do this mischief belong to the family _Anthomyinæ_; and there
are several species which have the perturbing habit of mining the
leaves of beets and spinach. It behooves those of us who are fond of
these “greens,” as our New England ancestors called them, to hold
every leaf up to the light before we put it into the skillet, lest
we get more meat than vegetable in these viands. The flies, who
thus take our greens ahead of us, are perhaps a little larger than
house-flies, and are generally gray in color with the front of the
head silver-white. These insects ought to teach us the value of clean
culture in our gardens, since they also mine in the smooth pigweed.
_References_--Manual for the Study of Insects, Comstock.
LESSON LXXVII
LEAF-MINERS
_Leading thought_--The serpent-like markings and the blister-like
blotches which we often see on leaves are made by the larvæ of
insects which complete their growth by feeding upon the inner living
substance of the leaf.
_Method_--The nasturtium leaf-miner is perhaps the most available for
this lesson since it may be found in its mine in early September.
However, the pupils should bring to the schoolroom all the leaves
with mines in them, that they can find and study the different forms.
_Observations_--1. Sketch the leaf with the mine in it, showing the
shape of the mine. What is the name of the plant on which the leaf
grew?
2. Hold the leaf up to the light, can you see the insect within the
mine? What is it doing? Are there more than one insect in the mine?
Open the mine and see how the miner looks.
3. There are three general types of mines: Those that are long,
curving lines called serpentine mines; those that begin small and
flare out, called trumpet mines; and those that are blister-like
called blotch mines. Which of these is the mine you are studying?
4. Study a serpentine mine. Note that where the little insect began
to eat, the mine is small. Why does it widen from this point? What
happened in the part which we call the serpent’s head?
5. Look closely with a lens and find if there is a break above the
mine in the upper surface of the leaf or below the mine in the
lower surface of the leaf. If the insect is no longer in the mine
can you find where it escaped? Can you find a shed pupa-skin in the
“serpent’s head?”
6. Why does an insect mine in a leaf? What does it find to eat? How
is it protected from the birds or insects of prey while it is getting
its growth?
7. Look on leaves of nasturtium, columbine, lamb’s quarters, dock
and burdock, for serpentine mines. Are the mines on these different
plants alike? Do you suppose they are made by the same insect?