mines. Are there more than one insect in these mines? If the insects
are present, hold the leaf out to the light and watch them eat.
9. Look in the leaves of pitch or other thick leaved pines (not white
pine), for pine needles which are yellow at the tip. Examine these
for miners. If the miner is not within, can you find the little
circular door by which it escaped? Would you think there was enough
substance in a half a pine needle to support a little creature while
it grew up?
10. If you find leaf-miners at work, do not pluck off the leaves
being mined but cover each with a little bag of swiss muslin tied
close about the petiole and thus capture the winged insect.
[Illustration: _Witch-hazel, showing work of leaf-rollers,
leaf-miners and gall-makers._]
THE LEAF-ROLLERS
_Teacher’s Story_
[Illustration: I]
If we look closely at sumac leaves before they are aflame from
autumn’s torch, we find many of the leaflets rolled into little
cornucopias fastened with silk. The silk is not in a web, like that
of the spider, but the strands are twisted together, hundreds of
threads combined in one strong cable, and these are fastened from
roll to leaf, like tent ropes. If we look at the young basswoods,
we find perhaps many of their leaves cut across, and the flap made
into a roll and likewise fastened with silken ropes. The witch-hazel,
which is a veritable insect tenement, also shows these rolls. In
fact, we may find them upon the leaves of almost any species of
tree or shrub, and each of these rolls has its own special maker or
indweller. Each species of insect, which rolls the leaves, is limited
to the species of plant on which it is found; and one of these
caterpillars would sooner starve than take a mouthful from a leaf of
any other plant. Some people think that insects will eat anything
that comes in their way; but of all created animals, insects are the
most fastidious as to their food.
[Illustration: _Leaf-rollers in sumac, with diagram showing the
fastening of the silk-stay-ropes._]
[Illustration:
_A leaf of basswood cut and rolled by the basswood leaf-roller._
Comstock. Manual.]
Some species of leaf-rollers unite several leaflets together, while
others use a single leaf. In the case of the sumac leaf-roller,
it begins in a single leaf; but in its later stages, it fastens
together two or three of the terminal leaflets in order to gain
more pasturage. The little silken tent ropes which hold the folded
leaves are well worth study with a lens. They are made of hundreds
of threads of the finest silk, woven from a gland opening near the
lower lip of the caterpillar. The rope is always larger where it is
attached to the leaf than at the center, because the caterpillar
crisscrosses the threads in order to make the attachment to the
leaf larger and firmer. Unroll a tent carefully, and you may see
the fastenings used in an earlier stage, and may even find the
first turned-down edge of the leaf. However, the center of a leaf
roller’s habitation is usually very much eaten, for the whole reason
for making its little house is that the soft-bodied caterpillar
may eat its fill completely hidden from the eyes of birds or other
animals. When it first hatches from the egg, it feeds for a short
time, usually on the under side of the leaf; but when still so small
that we can barely see it with the naked eye, it somehow manages to
fold over itself one edge of the leaf and peg it down. The problem
of how so small a creature is able to pull over and fold down or to
make in a roll a stiff leaf is hard to solve. I, myself, believe it
is done by making many threads, each a little more taut than the
last. I have watched several species working, and the leaf comes
slowly together as the caterpillar stretches its head and sways back
and forth hundreds of times, fastening the silk first to one side
and then to the other. Some observers believe that the caterpillar
throws its weight upon the silk, in order to pull the leaf together;
but in the case of the sumac leaf-roller, I am sure this is not
true, as I have watched the process again and again under a lens,
and could detect no signs of this method. Many of the caterpillars
which make rolls, change to small moths known as Tortricids. This
is a very large family, containing a vast number of species and not
all of the members are leaf-rollers. These little moths have the
front wings rather wide and more or less rectangular in outline. The
entomologists have a pleasing fashion of ending the names of all of
these moths with “ana;” the one that rolls the currant leaves is
_Rosana_, the one on juniper is _Rutilana_, etc. Since many of the
caterpillars of this family seek the ground to pupate and do not
appear as moths until the following spring, it is somewhat difficult
to study their complete life histories, unless one has well-made
breeding cages with earth at the bottom; and even then it is
difficult to keep them under natural conditions, since in an ordinary
living room the insects dry up and do not mature.
[Illustration: _Leaflets of locust, fastened together to make a nest
by the caterpillar of a butterfly._]
LESSON LXXVIII
THE LEAF-ROLLERS
_Leading thought_--There are many kinds of insects which roll the
leaves of trees and plants into tents, in which they dwell and feed
during their early stages.
_Method_--This is an excellent lesson for early autumn when the
pupils may find many of these rolled leaves, which they may bring
to the schoolroom, and which will give material for the lesson. The
rolls are found plentifully on sumac, basswood and witch-hazel.
_Observations_--1. What is the name of the trees and shrubs from
which these rolled leaves which you have collected were taken?
2. Are more than one leaf or leaflet used in making the roll?
3. Is the leaf rolled crosswise or lengthwise? How large is the tube
thus made?
4. Is the nest in the shape of a tube, or are several leaves fastened
together, making a box-shaped nest?
5. How is the roll made fast? Examine the little silken ropes with a
lens and describe one of them. Is it wider where it is attached to
the leaf than at the middle? Why?
6. How many of these tent ropes are there which make fast the roll?
Unroll a leaf carefully and see if you can find signs of the tent
ropes that fastened the roll together when it was smaller. Can you
find where it began?
7. As you unroll the leaves what do you see at the center? Has the
leaf been eaten? Can you discover the reason why the caterpillar made
this roll?
8. How do you think a caterpillar manages to roll a leaf so
successfully? Where is the spinning gland of a caterpillar? How does
the insect act when spinning threads back and forth when rolling the
leaf? What sort of insect does the caterpillar which rolls the leaf
change into? Do you suppose that the same kind of caterpillars makes
the rolls on two different species of trees?
9. In July or early August get some of the rolls with the
caterpillars in them, unroll a nest, take the caterpillar out and put
it on a fresh leaf of the same kind of tree or shrub on which you
found it, and watch it make its roll.
_Supplementary reading_--“A Dweller in Tents” and “A Little Nomad,”
in Ways of the Six-Footed.
[Illustration:
_The spiny oak-gall._
_The pointed bullet-gall on oak twigs._
_A cluster of galls on midrib of oak leaf._
_The acorn plum-gall._
Photo by L. H. Weld.]
THE GALL-DWELLERS
_He retired to his chamber, took his lamp, and summoned
the genius as usual. “Genius,” said he, “build me a palace
near the sultan’s, fit for the reception of my spouse, the
princess; but instead of stone, let the walls be formed of
massy gold and silver, laid in alternate rows; and let the
interstices be enriched with diamonds and emeralds. The palace
must have a delightful garden, planted with aromatic shrubs
and plants, bearing the most delicious fruits and beautiful
flowers. But, in particular, let there be an immense treasure
of gold and silver coin. The palace, moreover, must be well
provided with offices, storehouses, and stables full of
the finest horses, and attended by equerries, grooms, and
hunting equipage.” By the dawn of the ensuing morning, the
genius presented himself to Aladdin, and said, “Sir, your
palace is finished; come and see if it accords with your
wishes.”_
--ARABIAN NIGHTS ENTERTAINMENTS.
[Illustration: A]
Although Aladdin is out of fashion, we still have houses of magic
that are even more wonderful than that produced by his resourceful
lamp. These houses are built through an occult partnership between
insects and plant tissues; and no one understands just how they are
made, although we are beginning to understand a little concerning the
reasons for the growth. These houses are called galls and are thus
well named, since they grow because of an irritation to the plant
caused by the insect.
There are many forms of these gall-dwellings, and they may grow upon
the root, branch, leaf, blossom, or fruit. The miraculous thing
about them is that each kind of insect builds its magical house on
a certain part of a certain species of tree or plant; and the house
is always of a certain definite form on the outside and of a certain
particular pattern within. Many widely differing species of insects
are gall-makers; and he who is skilled in gall lore knows, when he
looks at the outside of the house, just what insect dwells within it.
[Illustration: _Oak apple, showing the larva of the gall insect._
Comstock’s Manual.]
We may take the history of the common oak apple, as an example. A
little, four-winged, fly-like creature lays its eggs, early in the
season, on the leaf of the scarlet oak. As soon as the larva hatches,
it begins to eat into the substance of one of the leaf veins. As it
eats, it discharges through its mouth into the tissues of the leaf, a
substance which is secreted from glands within its body. Immediately
the building of the house commences; out around the little creature
grow radiating vegetable fibers, showing by their position plainly
that the grub is the center of all of this new growth; meanwhile,
a smooth, thin covering completely encloses the globular house;
larger and larger grows the house until we are accustomed to call
it an oak apple, so large is it. The little chap inside is surely
content and happy, for it is protected from the sight of all of its
enemies, and it finds the walls of its house the best of food. It is
comparable to a boy living in the middle of a giant sponge cake, and
who when hungry would naturally eat out a larger cave in the heart
of the cake. After the inmate of the oak apple completes its growth,
it changes to a pupa and finally comes out into the world a tiny
four-winged fly, scarcely a quarter of an inch in length.
The story of the willow cone-gall is quite different. A little gnat
lays her eggs on the tip of the bud of a twig; as soon as the grub
hatches and begins to eat, the growth of the twig is arrested,
the leaves are stunted until they are mere scales and are obliged
to overlap in rows around the little inmate, thus making for it a
cone-shaped house which is very thoroughly shingled. The inhabitant
of this gall is a hospitable little fellow, and his house shelters
and feeds many other insect guests. He does not pay any attention to
them, being a recluse in his own cell, but he civilly allows them to
take care of themselves in his domain, and feed upon the walls of
his house. He stays in his snug home all winter and comes out in the
spring a tiny, two-winged fly.
[Illustration: _Willow cone-galls._
Photo by Verne Morton.]
[Illustration: _Spherical gall of goldenrod, opened, showing its
prosperous looking owner._
Photo by M. V Slingerland.]
There are two galls common on the stems of goldenrod. The more
numerous is spherical in form and is made by a fat and prosperous
looking little grub which later develops into a fly. But although it
is a fly that makes the globular gall in the stem of goldenrod, the
spindle-shaped gall often seen on the same stem has quite another
story. A little brown and gray mottled moth, about three-fourths
of an inch long, lays her egg on the stem of the young goldenrod.
The caterpillar, when it hatches, lives inside the stem, which
accommodatingly enlarges into an oblong room. The caterpillar feeds
upon the substance of the stem until it attains its growth, and then
seems to dimly realize something about its future needs. At least it
cuts, with its sharp jaws, a little oval door at the upper end of
its house and makes an even bevel by widening the opening toward the
outside. It then makes a little plug of debris which completely fills
the door; but because of the bevel, no intrusive beetle or ant can
push it in. Thus the caterpillar changes to a helpless pupa in entire
safety; and when the little moth issues from the pupa skin, all it
has to do is to push its head against the door, and out it falls, and
the recluse is now a creature of the outside world.
[Illustration: _Mossy rose-gall._
Comstock’s Manual.]
Many galls are compound, that is, they are made up of a community
of larvæ, each in its own cell. The mossy rose-gall is an instance
of this. The galls made by mites and aphids are open either below
or above the surface of the leaf; the little conical galls on
witch-hazel are examples of these. In fact, each gall has its own
particular history, which proves a most interesting story if we seek
to read it with our own eyes.
LESSON LXXIX
THE GALL-DWELLERS
_Leading thought_--The galls are protective habitations for the
little insects which dwell within them. Each kind of insect makes
its own peculiar gall on a certain species of plant, and no one
understands just how this is done or why it is so.
[Illustration: _Porcupine gall on leaf of white oak._
_Section of same showing cells._
_Female gallfly laying eggs in oak bud._
Photo by C. J. Triggerson.]
_Method_--Ask the pupils to bring in as many of these galls as
possible. Note that some have open doors and some are entirely
closed. Cut open a gall and see what sorts of insects are found
within it. Place each kind of gall in a tumbler or jar covered with
cheesecloth and place where they may be under observation for perhaps
several months; note what sort of winged insect comes from each.
_Observations_--1. On what plant or tree did this gall grow? Were
there many like it? Did they grow upon the root, stem, leaf, flower,
or fruit? If on the leaf, did they grow upon the petiole or the blade?
2. What is the shape of the little house? What is its color? Its
size? Is it smooth or wrinkled on the outside? Is it covered with
fuzz or with spines?
3. Open the gall; is there an insect within it? If so, where is it
and how does it look? What is the appearance of the inside of the
gall?
[Illustration: _Stem of golden-rod, showing the spherical gall above,
made by larva of a fly; and the spindle-shaped gall below, made by
the caterpillar of a moth._]
4. Is there a cell for the insect at the very center of the gall, or
are there many such cells?
5. Has the house an open door? If so, does the door open above or
below? Are there more than one insect in the galls with open doors?
What sort of insect makes this kind of house?
6. Do you find any insects besides the original gall-maker within it?
If so, what are they doing?
7. Of what use are these houses to their little inmates? How do they
protect them from enemies? How do they furnish them with food?
8. Do the gall insects live all their lives within the galls or do
they change to winged insects and come out into the world? If so, how
do they get out?
9. How many kinds of galls can you find upon oaks? Upon goldenrod?
Upon witch-hazel? Upon willow?
_Supplementary reading_--Outdoor Studies, Needham, pages 18 and 37;
“Houses of Oak,” in Insect Stories, Kellogg; Manual for the Study of
Insects.
* * * * *
_A green little world
With me at its heart!
A house grown by magic,
Of a green stem, a part._
_My walls give me food
And protect me from foes,
I eat at my leisure,
In safety repose._
_My house hath no window,
’Tis dark as the night!
But I make me a door
And batten it tight._
_And when my wings grow
I throw wide my door;
And to my green castle
I return nevermore._
THE GRASSHOPPER
_Teacher’s Story_
[Illustration: B]
Because the grasshopper affords special facilities for the study
of insect structure, it has indeed become a burden to the students
in the laboratories of American universities. But in nature-study
we must not make anything a burden, least of all the grasshopper,
which being such a famous jumper as well as flier, does not long
voluntarily burden any object.
Since we naturally select the most salient characteristic of a
creature to present first to young pupils, we naturally begin this
lesson with the peculiarity which makes this insect a “grasshopper.”
When any creature has unusually strong hind legs, we may be sure it
is a jumper, and the grasshopper shows this peculiarity at first
glance. The front legs are short, the middle legs a trifle longer,
but the femur of the hind leg is nearly as long as the entire body,
and contains many powerful muscles which have the appearance of being
braided, because of the way they are attached to the skeleton of the
leg; the tibia of the hind leg is long and as stiff as if made of
steel. When getting ready to jump the grasshopper lowers the great
femur below the level of the closed wings and until the tibia is
parallel with it and the entire foot is pressed against the ground.
The pair of double spines at the end of the tibia, just back of the
foot, are pressed against the ground like a spiked heel, and the
whole attitude of the insect is tense. Then, like a steel spring, the
long legs straighten and the insect is propelled high into the air
and far away. This is a remarkable example of insect dynamics; and
since so many species of birds feed upon the grasshopper, its leaping
power is much needed to escape them. However, when the grasshopper
makes a journey it uses its wings.
[Illustration: _Grasshopper with parts of external anatomy named._]
As we watch a grasshopper crawling up the side of a vial or tumbler
we can examine its feet with a lens. Between and in front of the
claws is an oval pad which clings to the glass, not by air pressure
as was once supposed, but by means of microscopic hairs, called
tenent hairs, which secrete a sticky fluid. Each foot consists of
three segments and a claw; when the insect is quiet, the entire foot
rests upon the ground; but when climbing on glass, the toe pads are
used.
[Illustration: _The nymph of the red-legged grasshopper, enlarged._
_Adult of red-legged grasshopper_
Comstock’s Manual.]
The grasshopper’s face has a droll expression; would that some
caricaturist could analyze it! It is a long face, and the compound
eyes placed high upon it, give a look of solemnity. The simple eyes
can be made out with a lens. There is one just in front of each big
eye, and another, like the naughty little girl’s curl, is “right in
the middle of the forehead.” The antennæ are short but alert. The
two pairs of palpi connected with the mouth-parts are easily seen,
likewise the two pairs of jaws, the notched mandibles looking like a
pair of nippers. We can see these jaws much better when the insect
is eating, which act is done methodically. First, it begins at one
edge of a leaf, which it seizes between the front feet so as to hold
it firm; it eats by reaching up and cutting downwards, making an
even-edged, long hole on the leaf margin; the hole is made deeper by
repeating the process. It sometimes makes a hole in the middle of
a leaf and bites in any direction, but it prefers to move the jaws
downward. While it is feeding, its palpi tap the leaf continually
and its whole attitude is one of deep satisfaction. There is an
uprolled expression to the compound eyes which reminds us of the way
a child looks over the upper edge of its cup while drinking milk.
The grasshopper has a preference for tender herbage, but in time of
drouth will eat almost any living plant.
Back of the head is a sun-bonnet-shaped piece, bent down at the
sides, forming a cover for the thorax. The grasshopper has excellent
wings, as efficient as its legs; the upper pair are merely strong,
thick, membranous covers, bending down at the sides so as to protect
the under wings; these wing-covers are not meant for flying and are
held stiff and straight up in the air, during flight. The true wings,
when the grasshopper is at rest, are folded lengthwise like a fan
beneath the wing-covers; they are strongly veined and circular in
shape, giving much surface for beating the air. The grasshoppers’
flight is usually swift and short; but in years of famine they
fly high in the air and for long distances, a fact recorded in the
Bible regarding the plague of locusts. When they thus appear in vast
hordes, they destroy all the vegetation in the region where they
settle.
The wings of grasshoppers vary in color, those of the red-legged
species being gray, while those of the Carolina locusts are black
with yellow edges. The abdomen is segmented, as in all insects, and
along the lower side there are two lengthwise sutures or creases
which open and shut bellows-like, when the grasshopper breathes. The
spiracles or breathing pores can be seen on each segment, just above
this suture.
The grasshopper has its ears well protected; to find them, we must
lift the wings in order to see the two large sounding disks, one on
each side of the first segment of the abdomen. These are larger and
much more like ears than are the little ears in the elbows of the
katydids.
The singing of the short-horned grasshoppers is a varied performance,
each species doing it in its own way. One species makes a most
seductive little note by placing the femur and tibia of the hind legs
together, and with the hind feet completely off the ground, the legs
are moved up and down with great rapidity, giving off a little purr.
The wings in this case, do not lift at all. There are other species
that make the sound by rubbing the legs against the wing-covers.
[Illustration: _Grasshopper cleaning its antenna._]
The grasshopper makes its toilet thus: It cleans first the hind feet
by rubbing them together and also by reaching back and scrubbing
them with the middle feet; the big hind femur it polishes with the
bent elbow of the second pair of legs. It cleans the middle feet by
nibbling and licking them, bending the head far beneath the body in
order to do it. It polishes its eyes and face with the front feet,
stopping to lick them clean between whiles, and it has a most comical
manner of cleaning its antennæ; this is accomplished by tipping the
head sidewise, and bending it down so that the antenna of one side
rests upon the floor; it then plants the front foot of that side
firmly upon the antenna and pulls it slowly backward between the foot
and floor.
The grasshopper has some means of defence as well as of escape;
it can give a painful nip with its mandibles; and when seized, it
emits copiously from the mouth a brownish liquid which is acrid and
ill-smelling. This performance interests children, who are wont to
seize the insect by its jumping legs and hold it up, commanding it to
“chew tobacco.”
Grasshoppers are insects with incomplete metamorphosis, which merely
means that the baby grasshopper, as soon as it emerges from the egg,
is similar in form to its parent except that it has a very large head
and a funny little body, and that it has no quiet stage during life.
When immature, the under wings or true wings have a position outside
of the wing-covers and look like little fans.
The short-horned grasshoppers lay their eggs in oval masses protected
by a tough overcoat. The ovipositor of the mother grasshopper is
a very efficient tool, and with it she makes a deep hole in the
ground, or sometimes in fence rails or other decaying wood; after
placing her eggs in such a cavity, she covers the hiding place with
a gummy substance so that no intruders or robbers may work harm to
her progeny. Most species of grasshoppers pass the winter in the egg
stage; but sometimes we find in early spring the young ones which
hatched in the fall, and they seem as spry as if they had not been
frozen stiff.
LESSON LXXX
THE RED-LEGGED
GRASSHOPPER
_Leading thought_--The grasshopper feeds upon grass and other herbage
and is especially fitted for living in grassy fields. Its color
protects it from being seen by its enemies the birds. If attacked, it
escapes by long jumps and by flight. It can make long journeys on the
wing.
[Illustration: _The mouth-parts of a grasshopper dissected off,
enlarged and named._]
_Method_--The red-legged grasshopper (_M. femur-rubrum_) has
been selected for this lesson because it is the most common of
all grasshoppers, though other species may be used as well. The
red-legged locust, or grasshopper has, as is indicated by its
name, the large femur of the hind legs reddish in color. Place the
grasshopper under a tumbler and upon a spray of fresh herbage, and
allow the pupils to observe it at leisure. It might be well to
keep some of the grasshoppers in a cage similar to that described
for crickets. When studying the feet, or other parts of the insect
requiring close scrutiny, the grasshopper should be placed in a vial
so that it may be passed around and observed with a lens. Give the
questions a few at a time, and encourage the pupils to study these
insects in the field.
[Illustration: _Front leg of katydid, showing ear near elbow._
Comstock’s Manual.]
_Observations_--1. Since a grasshopper is such a high jumper,
discover if you can how he does this “event.” Which pair of legs is
the longest? Which the shortest? How long are the femur and tibia
of the hind leg compared with the body. What do you think gives the
braided appearance to the surface of the hind femur? What is there
peculiar about the hind femur? Note the spines at the end of the
tibia just behind the foot.
2. Watch the grasshopper prepare to jump and describe the process.
How do you think it manages to throw itself so far? If a man were as
good a jumper as a grasshopper in comparison to his size, he could
jump 300 feet high or 500 feet in distance. Why do you think the
grasshopper needs to jump so far?
3. As the grasshopper climbs up the side of a tumbler or vial, look
at its feet through a lens and describe them. How many segments are
there? Describe the claws. How does it cling to the glass? Describe
the little pad between the claws.
[Illustration: _Long horned, or meadow grasshopper._]
4. Look the grasshopper in the face. Where are the compound eyes
situated? Can you see the tiny simple eyes like mere dots? How many
are there? Where are they? How long are the antennæ? For what are
they used?
5. How does a grasshopper eat? Do the jaws move up and down or
sidewise? What does the grasshopper eat? How many pairs of palpi can
you see connected with the mouth-parts? How are these used when the
insect is eating? When there are many grasshoppers, what happens to
the crops?
6. What do you see just back of the grasshopper’s head, when looked
at from above?
[Illustration: _Wing of male and of female meadow grasshoppers._
Comstock’s Manual.]
7. Can the grasshopper fly as well as jump? How many pairs of wings
has it? Does it use the first pair of wings to fly with? How does
it hold them when flying? Where is the lower or hind pair of wings
when the grasshopper is walking? How do they differ in shape from the
front wings?
8. Note the abdomen. It is made of many rings or segments. Are these
rings continuous around the entire body? Where do their breaks occur?
Describe the movement of the abdomen as the insect breathes. Can you
see the spiracles or breathing pores? Lift the wings, and find the
ear on the first segment of the abdomen.
9. If you seize the grasshopper how does it show that it is offended?
10. How does the grasshopper perform its toilet? Describe how it
cleans its antennæ, face and legs.
11. What becomes of the grasshoppers in the winter? Where are the
eggs laid? How can you tell a young from a full-grown grasshopper?
12. Do all grasshoppers have antennæ shorter than half the length of
their bodies? Do some have antennæ longer than their bodies? Where
are the long-horned grasshoppers found? Describe how they resemble
the katydids in the way they make music and in the position of their
ears.
[Illustration: _Short-horned and long-horned, or meadow,
grasshoppers._]
_Supplementary reading_--Chapters XVI-XVIII in Grasshopper Land,
Morley.
THE KATYDID
_Teacher’s Story_
“_I love to hear thine earnest voice
Wherever thou art hid,
Thou testy little dogmatist,
Thou pretty katydid,
Thou mindest me of gentle folks,
Old gentle folks are they,
Thou say’st an undisputed thing
In such a solemn way._”
HOLMES.
[Illustration: D]
Distance, however, lends enchantment to the song of the katydid,
for it grates on our nerves as well as on our ears, when at close
quarters. The katydid makes his music in a manner similar to that
of the cricket but is not, however, so well equipped since he has
only one file and only one scraper for playing. As with the meadow
grasshoppers and crickets, only the males make the music, the wings
of the females being delicate and normally veined at the base. The
ears, too, are in the same position as those of the cricket, and may
be seen as a black spot in the front elbow. The song is persistent
and may last the night long: “Katy did, she didn’t she did.” James
Whitcomb Riley says, “The katydid is rasping at the silence,” and the
word rasping well describes the note.
[Illustration: _The front portions of the wings of a male katydid
showing file on one wing and scraper on the other._]
The katydids are beautiful insects, with green, finely veined,
leaf-like wing-covers under which is a pair of well developed wings,
folded like fans; they resemble in form the long-horned grasshoppers.
The common northern species (_Cyrtophyllus_) is all green above
except for the long, delicate, fawn-colored antennæ and the brownish
fiddle of the male, which consists of a flat triangle just back of
the thorax where the wing-covers overlap. Sometimes this region is
pale brown and sometimes green, and with the unaided eye we can
plainly see the strong cross-vein, bearing the file. The green
eyes have darker centers and are not so large as the eyes of the
grasshopper. The body is green with white lines below on either side.
There is a suture the length of the abdomen in which are placed the
spiracles. The insect breathes by sidewise expansion and contraction,
and the sutures rhythmically open and shut; when they are open, the
spiracles can be seen as black dots. The legs are slender and the
hind pair, very long. The feet are provided with two little pads, one
on each side of the base of the claw. In the grasshopper there is
only one pad which is placed between the two hooks of the claw. The
female has a green, sickle-shaped ovipositor at the end of the body.
With this she lays her flat, oval eggs, slightly over-lapping in a
neat row.
The katydids are almost all dwellers in trees and shrubs; although
I have often found our common species upon asters and similar high
weeds. The leaf-like wings of these insects are, in form and color,
so similar to the leaves that they are very completely hidden. The
katydid is rarely discovered except by accident; although when one
is singing, it may be approached and ferreted out with the aid of a
lantern.
The katydid, when feeding, often holds the leaf or the flower firmly
with the front feet, while biting it off like a grazing cow, and if
it is tough, chews it industriously with the sidewise working jaws.
A katydid will often remain quiet a long time with one long antenna
directed forward and the other backward, as if on the lookout for
news from the front and the rear. But when the katydid “cleans up,”
it does a thorough job. It nibbles its front feet, paying special
attention to the pads, meanwhile holding the foot to its mandibles
with the aid of the palpi. But once washing is not enough; I have
seen a katydid go over the same foot a dozen times in succession,
beginning always with the hind spurs of the tibia and nibbling along
the tarsus to the claws. It cleans its face with its front foot,
drawing it downward over the eye and then licking it clean. It cleans
its antenna with its mandibles by beginning at the base and drawing
it up in a loop as fast as finished. After watching the process of
these lengthy ablutions, we must conclude that the katydid is among
the most fastidious members of the insect “four hundred.”
_References_--Manual for Study of Insects, Comstock; American
Insects, Kellogg; Ways of Six Footed, Comstock; Grasshopper Land,
Morley.
[Illustration: _The angular-winged katydid and her eggs._
Comstock’s Manual.]
LESSON LXXXI
THE KATYDID
_Leading thought_--The katydids resemble the long-horned grasshoppers
and the crickets. They live in trees, and the male sings “katy-did”
by means of a musical instrument similar to that of the cricket.
_Method_--Place a katydid in a cricket cage in the schoolroom, giving
it fresh leaves or flowers each day, and encouraging the pupils to
watch it at recess. It may be placed in a vial and passed around, for
close observation. In studying this insect, use the lesson on the
red-legged grasshopper and also that on the cricket. These lessons
will serve to call the attention of the pupils to the differences and
resemblances between the katydid and these two allied insects.
[Illustration: _A pair of dusky lovers._
Drawing by Ida Baker.]
_THE BLACK CRICKETS_
_Of the insect musicians the cricket is easily the most
popular. Long associated with man, as a companion of the
hearth and the field, his song touches ever the chords of
human experience. Although we, in America, do not have
the house-cricket which English poets praise, yet our
field-crickets have a liking for warm corners, and will, if
encouraged, take up their abode among our hearthstones. The
greatest tribute to the music of the cricket is the wide range
of human emotion which it expresses. “As merry as a cricket”
is a very old saying and is evidence that the cricket’s
fiddling has ever chimed with the gay moods of dancers and
merrymakers. Again, the cricket’s song is made an emblem of
peace; and again we hear that the cricket’s “plaintive cry”
is taken as the harbinger of the sere and dying year. From
happiness to utter loneliness is the gamut covered by this
sympathetic song. Leigh Hunt found him glad and thus addresses
him_:
“_And you, little housekeeper who class
With those who think the candles come too soon,
Loving the fire, and with your tricksome tune
Nick the glad, silent moments as they pass._”
WAYS OF THE SIX-FOOTED.
THE BLACK CRICKET
_Teacher’s Story_
[Illustration: I]
If we wish to become acquainted with these charming little
troubadours of the field, we should have a cricket cage with a pair
of them within it. They are most companionable, and it is interesting
to note how quickly they respond to a musical sound. I had a pair in
my room at one time, when I lived very near a cathedral. Almost every
time that the bells rang during the night, my cricket would respond
with a most vivacious and sympathetic chirping.
The patent leather finish to this cricket’s clothes is of great use;
for, although the cricket is an efficient jumper, it is after all,
mostly by running between grass blades that it escapes its enemies.
If we try to catch one, we realize how slippery it is, and how
efficiently it is thus able to slide through the fingers.
[Illustration: _The wing of male cricket enlarged._
a, file b, scraper.]
[Illustration: _A section of the file enlarged._]
[Illustration: _The front leg of a cricket enlarged showing ear at_
a.]
The haunts of the cricket are usually sunny; it digs a little
cave beneath a stone or clod in some field, where it can have the
whole benefit of all the sunshine, when it issues from its door.
These crickets cannot fly, since they have no wings under their
wing-covers, as do the grasshoppers. The hind legs have a strong
femur, and a short but strong tibia with downward slanting spines
along the hind edge, which undoubtedly help the insect in scrambling
through the grass. At the end of the tibia, next to the foot, is a
rosette of five spines, the two longer ones slanting to meet the
foot; these spines give the insect a firm hold, when making ready for
its spring. When walking, the cricket places the whole hind foot flat
on the ground, but rests only upon the claw and the segment next to
it, of the front pairs of feet. The claws have no pads like those of
the katydid or grasshopper; the segment of the tarsus next the claw
has long spines on the hind feet and shorter spines on the middle and
front feet, thus showing that the feet are not made for climbing,
but for scrambling along the ground. When getting ready to jump, the
cricket crouches so that the tibia and femur of the hind legs are
shut together and almost on the ground. The dynamics of the cricket’s
leap are well worth studying.
The cricket’s features are not so easily made out, because the head
is polished and black; the eyes are not so polished as the head,
and the simple eyes are present but are discerned with difficulty.
The antennæ are longer than the body and very active; there is a
globular segment where they join the face. I have not discovered that
the crickets are so fastidious about keeping generally clean as are
some other insects, but they are always cleaning their antennæ: I
have seen a cricket play his wing mandolin lustily and at the same
time carefully clean his antennæ; he polished these by putting up a
foot and bending the antenna down so that his mouth reached it near
the base; he then pulled the antenna through his jaws with great
deliberation, nibbling it clean to the very end. The lens reveals to
us that the flexibility of the antennæ is due to the fact that they
are many jointed. The palpi are easily seen, a large pair above and
a smaller pair beneath the “chin.” The palpi are used to test food
and prove if it be palatable. The crickets are fond of melon or other
sweet, juicy fruits, and by putting such food into the cage we can
see them bite out pieces with their sidewise working jaws, chewing
the toothsome morsel with gusto. They take hold of the substance they
are eating with the front feet as if to make sure of it.
[Illustration: _Male and female of the common black cricket, showing
differences in their wings. The male is below._
Photo by M. V. Slingerland.]
The wing-covers of the cricket are bent down at the sides at right
angles, like a box cover. The wing-covers are much shorter than the
abdomen and beneath them are vestiges of wings, which are never used.
The male has larger wing-covers than the female, and they are veined
in a peculiar scroll pattern. This veining seems to be a framework
for the purpose of making a sounding board of the wing membrane,
by stretching it out as a drum-head is stretched. Near the base of
the wing-cover, there is a heavy cross-vein covered with transverse
ridges, which is called the file; on the inner edge of the same
wing, near the base, is a hardened portion called the scraper. When
he makes his cry, the cricket lifts his wing-covers at an angle of
forty-five degrees and draws the scraper of the under wing against
the file of the overlapping one; lest his musical apparatus become
worn out, he can change by putting the other wing-cover above. The
wing-covers are excellent sounding boards and they quiver as the
note is made, setting the air in vibration, and sending the sound a
long distance. The female cricket’s wing-covers are more normal in
venation; and she may always be distinguished from her spouse by the
long sword-like ovipositor at the end of her body; this she thrusts
into the ground when she lays her eggs, thus placing them where they
will remain safely protected during the winter. Both sexes have a
pair of “tail feathers,” as the children call them, which are known
as the cerci (_sing. cerca_) and are fleshy prongs at the end of the
abdomen.
There would be no use of the cricket’s playing his mandolin if there
were not an appreciative ear to listen to his music. This ear is
placed most conveniently in the tibia of the front leg, so that the
crickets literally hear with their elbows, as do the katydids and the
meadow grasshoppers. The ear is easily seen with the naked eye as a
little white, disklike spot.
The chirp of the cricket is, in literature, usually associated with
the coming of autumn; but the careful listener may hear it in early
summer, although the song is not then so insistent as later in the
season. He usually commences singing in the afternoon and keeps it
up periodically all night. I have always been an admirer of the
manly, dignified methods of this little “minnesinger,” who does not
wander abroad to seek his lady love but stands sturdily at his own
gate, playing his mandolin the best he is able; he has faith that his
sable sweetheart is not far away, and that if she likes his song she
will come to him of her own free will. The cricket is ever a lover
of warmth and his mandolin gets out of tune soon after the evenings
become frosty. He is a jealous musician. When he hears the note of a
rival, he at once “bristles up,” lifting his wings at a higher angle
and giving off a sharp militant note. If the two rivals come in sight
of each other, there is a fierce duel. They rush at each other with
wide open jaws, and fight until one is conquered and retreats, often
minus an antenna, cerca, or even a leg. The cricket’s note has a
wide range of expression. When waiting for his lady love, he keeps
up a constant droning; if he hears his rival, the tone is sharp and
defiant; but as the object of his affection approaches, the music
changes to a seductive whispering, even having in it an uncertain
quiver, as if his feelings were too strong for utterance.
_References_--Manual for Study of Insects, p. 115; Insect Musicians;
Ways of the Six Footed, Comstock.
LESSON LXXXII
THE BLACK CRICKET
_Leading thought_--The crickets are among the most famous of the
insect musicians. They live in the fields under stones and in
burrows, and feed upon grass and clover. As with the song birds,
the male only makes music; he has his wing-covers developed into a
mandolin or violin, which he plays to attract his mate and also for
his own pleasure.
[Illustration: _A cricket cage._]
_Method_--Make some cricket cages as follows: Take a small flower-pot
and plant in it a root of fresh grass or clover. Place over this and
press well into the soil a lantern or lamp chimney. Cover the top
with mosquito netting. Place the pot in its saucer, so that it may
be watered by keeping the saucer filled. Ask the pupils to collect
some crickets. In each cage, place a male and one or more females,
the latter being readily distinguished by the long ovipositors.
Place the cages in a sunny window, where the pupils may observe
them at recess, and ask for the following observations. In studying
the cricket closely, it may be well to put one in a vial and pass
it around. In observing the crickets eat, it is well to give them a
piece of sweet apple or melon rind, as they are very fond of pulpy
fruits.
_Observations_--1. Is the covering of the cricket shining, like black
patent leather, or is it dull? What portions are dull? Of what use do
you think it is to the cricket to be so smoothly polished?
2. Where did you find the crickets? When you tried to catch them, how
did they act? Did they fly like grasshoppers or did they run and leap?
3. Look carefully at the cricket’s legs. Which is the largest of the
three pairs? Of what use are these strong legs? Look carefully at the
tibia of the hind leg. Can you see the strong spines at the end, just
behind the foot or tarsus? Watch the cricket jump and see if you can
discover the use of these spines. How many joints in the tarsus? Has
the cricket a pad like the grasshopper’s between its claws? When the
cricket walks or jumps does it walk on all the tarsus of each pair of
legs?
4. Study the cricket’s head. Can you see the eyes? Describe the
antennæ--their color, length, and the way they are used. Watch the
cricket clean its antennæ and describe the process. Can you see the
little feelers, or palpi, connected with the mouth? How many are
there? How does it use these feelers in tasting food before it eats?
Watch the cricket eat, and see whether you can tell whether its mouth
is made for biting or sucking.
5. Study the wings. Are the wings of the mother cricket the same size
and shape as those of her mate? How do they differ? Does the cricket
have any wings under these front wings, as the grasshopper does? Note
the cricket when he is playing his wing mandolin to attract his mate.
How does he make the noise? Can you see the wings vibrate? Ask your
teacher to show you a picture of the musical wings of the cricket, or
to show you the wings themselves under the microscope, so that you
may see how the music is made.
6. Why does the mother cricket need such a long ovipositor? Where
does she put her eggs in the fall to keep them safe until spring?
7. Look in the tibia, or elbow, of the front leg for a little white
spot. What do you suppose this is? Are there any white spots like it
on the other legs? Ask your teacher to tell you what this is.
8. Can you find the homes of the crickets in the fields? Do the black
crickets chirp in the day-time or after dark? Do they chirp in cold
or windy weather, or only when the sun shines?
_Supplementary Reading_--Grasshopper Land, Morley, Chapter XIX.
_CRICKET SONG._
_Welcome with thy clicking, cricket!
Clicking songs of sober mirth;
Autumn, stripping field and thicket,
Brings thee to my hearth,
Where thy clicking shrills and quickens,
While the mist of twilight thickens._
* * * * *
_No annoy, good-humored cricket,
With thy trills is ever blent;
Spleen of mine, how dost thou trick it
To a calm content?
So, by thicket, hearth, or wicket,
Click thy little lifetime, cricket!_
BAYARD TAYLOR.
THE SNOWY TREE-CRICKET
_Teacher’s Story_
[Illustration: T]
This is a slim, ghost-like cricket. It is pale green, almost white
in color, and about three-fourths of an inch long. Its long, slender
hind legs show that it is a good jumper. Its long antennæ, living
threads, pale gray in color, join the head with amber globe-like
segments. The pale eyes have a darker center and the palpi are very
long. The male has the wing-covers shaped and veined like those of
the black cricket, but they are not so broad and are whitish and very
delicate. The wings beneath are wide, for these crickets can fly. The
female has a long, sword-like ovipositor.
The snowy tree-cricket, like its relatives, spends much time at its
toilet. It whips the front foot over an antenna and brings the base
of the latter to the mandibles with the palpi and then cleans it
carefully to the very tip. It washes its face with the front foot,
always with a downward movement. If the hind foot becomes entangled
in anything it first tries to kick it clean, and then drawing it
beneath the body, bends the head so as to reach it with the mandibles
and nibbles it clean. The middle foot it also thrusts beneath the
body, bringing it forward between the front legs for cleaning. But
when cleaning its front feet, the snowy tree-cricket puts on airs;
it lifts the elbow high and draws the foot through the mouth with a
gesture very like that of a young lady with a seal ring on her little
finger, holding the ornate member out from its companions as if it
were stiff with a consciousness of its own importance.
[Illustration: _Eggs of snowy tree-cricket, laid in raspberry cane._
After C. V. Riley.]
There are two common species of the snowy tree-crickets which can
hardly be separated except by specialists or by watching their
habits. One is called “the whistler” and lives on low shrubs or
grass; it gives a clear, soft, prolonged, unbroken note. The other
is called “the fiddler” and lives on shrubs and in trees and vines.
Its note is a pianissimo performance of the katydid’s song; it is
delightful, rhythmic and sleep-inspiring; it begins in the late
afternoon and continues all night until the early, cold hours of
the approaching dawn. The vivacity of the music depends upon the
temperature, as the notes are given much more rapidly during the hot
nights.
“So far as we know, this snowy tree-cricket is the only one of the
insect musicians that seems conscious of the fact that he belongs
to an orchestra. If you listen on a September evening, you will
hear the first player begin; soon another will join, but not in
harmony at first. For some time there may be a see-saw of accented
and unaccented notes; but after a while the two will be in unison;
perhaps not, however, until many more players have joined the
concert. When the rhythmical beat is once established it is in as
perfect time as if governed by the baton of a Damrosch or a Thomas.
The throbbing of the cricket heart of September, it has been fitly
named. Sometimes an injudicious player joins the chorus at the wrong
beat, but he soon discovers his error and rectifies it. Sometimes,
also, late at night, one part of the orchestra in an orchard gets out
of time with the majority, and discord may continue for some moments,
as if the players were too cold and too sleepy to pay good attention.
This delectable concert begins usually in the late afternoons and
continues without ceasing until just before dawn the next morning.
Many times I have heard the close of the concert; with the “wee
sma” hours the rhythmic beat becomes slower; toward dawn there is
a falling off in the number of players; the beat is still slower,
and the notes are hoarse, as if the fiddlers were tired and cold;
finally, when only two or three are left the music stops abruptly.”
(_Ways of the Six-Footed_, Comstock.)
[Illustration: _Snowy tree cricket._]
The lesson on this cricket may be adapted from that on the black
cricket.
THE COCKROACH
_Teacher’s Story_
[Illustration: C]
Cockroaches in our kitchens are undoubtedly an unmitigated nuisance,
and yet, as in many other instances, when we come to consider
the individual cockroach, we find him an interesting fellow and
exceedingly well adapted for living in our kitchens despite us.
In shape, the cockroach is flat, and is thus well adapted to slide
beneath utensils and into crevices and corners. Its covering is
smooth and polished like patent leather, and this makes it slippery
and enables it to get into food without becoming clogged by the
adherence of any sticky substance. The antennæ are very long and
flexible and can be bent in any direction. They may be placed far
forward to touch things which the insect is approaching, or may
be placed over the back in order to be out of the way. They are
like graceful, living threads, and the cockroach tests its whole
environment with their aid. The mouth has two pairs of palpi or
feelers, one of which is very long and noticeable; these are kept in
constant motion as if to test the appetizing qualities of food. The
mouth-parts are provided with jaws for biting and, like all insect
jaws, these work sidewise instead of up and down. The eyes are black
but not prominent or large, and seem to be merely a part of the
sleek, polished head-covering.
[Illustration: _Croton bug._]
Some species of cockroaches have wings, and some do not. Those which
have wings, have the upper pair thickened and used for wing-covers.
The under pair are thinner and are laid in plaits like a fan. The
wing-covers are as polished as the body and quite as successful in
shedding dirt.
[Illustration: _Cockroach laying her case of eggs._
Photo by M. V. Slingerland.]
The legs are armed with long spines which are very noticeable and
might prove to be a disadvantage in accumulating filth; but they are
polished also; and too, this insect spends much time at its toilet.
Cockroaches run “like a streak”, children say; so speedily, indeed,
do they go that they escape our notice, although we may be looking
directly at them. This celerity in vanishing, saves many a cockroach
from being crushed by an avenging foot.
When making its toilet, the cockroach draws its long antenna through
its jaws as if it were a whiplash, beginning at the base and
finishing at the tip. It cleans each leg by beginning near the body
and so stroking downward the long spines which seem to shut against
the leg. It nibbles its feet clean to the very claws, and scrubs its
head vigorously with the front femur.
[Illustration: _Egg-case of cockroach._]
The cockroach’s eggs are laid in a mass enclosed in a pod-shaped
covering, which is waterproof and polished and protects its contents
from dampness. When the cockroaches, or the croton bugs, as the small
introduced species of cockroach is called, once become established in
a house, the only way to get rid of them is to fumigate the kitchen
with carbon bisulphide which is a dangerous performance and should be
done only by an expert.
LESSON LXXXIII
THE COCKROACH
_Leading thought_--The cockroach is adapted for living in crevices,
and although its haunts may be anything but clean, the cockroach
keeps itself quite clean. The American species live in fields and
woods and under stones and sticks and only occasionally venture into
dwellings. The species that infest our kitchens and water-pipes are
European.
_Method_--Place a cockroach in a vial with bread, potato or some
other food, cork the vial, and pass it around so that the children
may observe the prisoner at their leisure.
_Observations_--1. What is the general shape of the cockroach? Why is
this an advantage? What is the texture of its covering? Why is this
an advantage?
2. Describe the antennæ and the way they are used. Note the two
little pairs of feelers at the mouth. If possible, see how they are
used when the cockroach is inspecting something to eat. Can you see
whether its mouth is fitted for biting, lapping or sucking its food?
3. Note the eyes. Are they as large and prominent as those of the
bees or butterflies?
4. Has this cockroach wings? If so, how many and what are they like?
Note two little organs at the end of the body. These are the cerci,
like those of the crickets.
5. Describe the general appearance of the cockroach’s legs, and tell
what you think about its ability as a runner.
6. Note how the cockroach cleans itself and how completely and
carefully this act is performed. Have you ever seen cockroach’s eggs?
If so, describe them.
7. How can you get rid of cockroaches if they invade your kitchen?
LESSON LXXXIV
HOW TO MAKE AN AQUARIUM
[Illustration: T]
The schoolroom aquarium may be a very simple affair and still be
effective. Almost any glass receptacle will do, glass being chosen
because of its transparency, so that the life within may be observed.
Tumblers, jelly tumblers, fruit jars, butter jars, candy jars
and battery jars are all available for aquaria. The tumblers are
especially recommended for observing the habits of aquatic insects.
_To make an aquarium_: 1. Place in the jar a layer of sand an inch or
more in depth.
2. In this sand plant the water plants which you find growing under
water in a pond or stream; the plants most available are Water-weed,
Bladderwort, Water Starwort, Watercress, Stoneworts, Frog-spittle or
Water-silk.
3. Place on top a layer of small stones or gravel; this is to hold
the plants in place.
4. Tip the jar a little and pour in very gently at one side water
taken from a pond or stream. Fill the jar to within two or three
inches of the top; if it be a jelly tumbler, fill to within an inch
of the top.
5. Let it settle.
6. Place it in a window which does not get too direct sunlight. A
north window is the best place; if there is no north window to the
school room, place it far enough at one side of some other window so
that it will not receive too much sunlight.
7. To get living creatures for the aquarium use a dip-net, which is
made like a shallow, insect net.
8. Dip deep into the edges of the pond and be sure to bring up some
of the leaves and mud, for it is in these that the little water
animals live.
9. As fast as dipped up, these should be placed in a pail of water,
so that they may be carried to the schoolroom.
10. In introducing the water animals into the aquarium it is well to
put but a few in each jar.
[Illustration: _A humble, but useful, aquarium._]
_The care of the aquarium_--Care should be taken to preserve the
plant life in the aquarium, as the plants are necessary to the life
of the animals. They not only supply the food, but they give off
oxygen which the animals need for breathing, and they also take up
from the water the poisonous carbonic acid gas given off from the
bodies of the animals.
1. The aquarium should be kept where there is a free circulation of
air.
2. If necessary to cover the aquarium to prevent the insects, like
the water boatmen and water beetles, from escaping, tie over it a
bit of mosquito netting, or lay upon the top a little square of wire
netting used for window screens.
3. The temperature should be kept rather cool; it is better that the
water of the aquarium should not be warmer than 50 deg. Fahrenheit,
but this is not always possible in the schoolroom.
4. If any insects or animals die in the aquarium they should be
removed at once, as the decomposing bodies render the water foul.
5. To feed the animals that live upon other animals take a bit of raw
beef, tie a string to it and drop it in, leaving the free end of the
string outside of the jar. After it has been in one day, pull it out;
for if it remains longer it will make the water foul.
6. As the water evaporates it should be replaced with water from the
pond.
_References_--The Fresh Water Aquarium, Eggeling and Ehrenberg;
Insect Life, Comstock; The Brook Book, Miller; Nature Study and Life,
Hodge; The Home Aquarium, How to Care for It, Eugene Smith.
[Illustration: _An inexpensive and durable aquarium._]
THE DRAGON-FLIES AND DAMSEL-FLIES
_Teacher’s Story_
[Illustration: A]
A pond without dragon-flies darting above it, or without the
exquisitely iridescent damsel-flies clinging to the leaves of its
border would be a lonely place indeed. As one watches these beautiful
insects, one wonders at the absurd errors which have crept into
popular credence about them. Who could be so silly as to believe that
they could sew up ears or that they could bring dead snakes to life!
The queer names of these insects illustrate the prejudices of the
ignorant--devil’s darning needles, snake doctors, snake feeders, etc.
Despite all this slander, the dragon-flies remain not only entirely
harmless to man, but in reality are his friends and allies in waging
war against flies and mosquitoes; they are especially valuable in
battling mosquitoes since the nymphs, or young, of the dragon-fly,
take the wrigglers in the water, and the adults, on swiftest wings,
take the mosquitoes while hovering over ponds laying their eggs.
[Illustration: _The ten-spot._
From Outdoor Studies, Needham.]
The poets have been lavish in their attention to these interesting
insects and have paid them delightful tributes. Riley says:
“_Till the dragon fly, in light gauzy armor burnished bright,
Came tilting down the waters in a wild, bewildered flight._”
While Tennyson drew inspiration for one of his most beautiful poems
from the two stages of dragon-fly life. But perhaps Lowell in that
exquisite poem, “The Fountain of Youth,” gives us the perfect
description of these insects:
_In summer-noon flushes
When all the wood hushes,
Blue dragon-flies knitting
To and fro in the sun,
With sidelong jerk flitting,
Sink down on the rushes,
And, motionless sitting,
Hear it bubble and run,
Hear its low inward singing,
With level wings swinging
On green tasselled rushes,
To dream in the sun._
It is while we, ourselves, are dreaming in the sun by the margin of
some pond, that these swift children of the air seem but a natural
part of the dream. Yet if we waken to note them more closely, we find
many things very real to interest us. First, they are truly children
of the sun, and if some cloud throws its shadow on the waters
for some moments, the dragon-flies disappear as if they wore the
invisible cloak of the fairy tale. Only a few of the common species
fly alike in shade and sunshine, and early and late. The best known
of these is the big, green skimmer, which does not care so much for
ponds, but darts over fields and even dashes into our houses, now
and then. Probably it is this species which has started all of the
dragon-fly slander, for it is full of curiosity, and will hold itself
on wings whirring too rapidly to even make a blur, while it examines
our faces or inspects the pictures or furniture or other objects
which attract it.
[Illustration: _A common dragon-fly._
Comstock’s Manual.]
Another thing we may note when dreaming by the pond is that the
larger species of dragon-flies keep to the higher regions above the
water, while the smaller species and the damsel-flies flit near
its surface. Well may the smaller species keep below their fierce
kindred, otherwise they would surely be utilized to sate their
hunger, for these insects are well named dragons, and dragons do not
stop to inquire whether their victims are relatives or not. It is
when they are resting, that the dragon and damsel-flies reveal their
most noticeable differences. The dragon-fly extends both wings as if
in flight while it basks in the sun or rests in the shadow. There is
a big, white-bodied species called the whitetail which slants its
wings forward and down when it rests; but the damsel-flies fold their
wings together over the back when resting. The damsel-flies have more
brilliantly colored bodies than do the dragon-flies, many of them
being iridescent green or coppery; they are more slender and delicate
in form. The damsel-fly has eyes which are so placed on the sides of
the head as to make it look like a cross on the front of the body
fastened to the slender neck, and with an eye at the tip of each arm.
There are very many species of dragon and damsel-flies, but they all
have the same general habits.
[Illustration: _A damsel-fly._
Outdoor Studies, Needham.]
The dragon-fly nymphs are the ogres of the pond or stream. To anyone
unused to them and their ways in the aquarium, there is a surprise
in store, so ferocious are they in their attacks upon creatures
twice their size. The dragon-fly’s eggs are laid in the water;
in some instances they are simply dropped and sink to the bottom;
but in the case of damsel-flies, the mother punctures the stems of
aquatic plants and places the eggs within them. The nymph in no wise
resembles the parent dragon-fly. It is a dingy little creature, with
six queer, spider-like legs and no wings; although there are four
little wing-pads extending down its back, which encase the growing
wings. It may remain hidden in the rubbish at the bottom of the pond
or may cling to water weeds at the sides, for different species have
different habits. But in them all we find a most amazing lower lip.
This is so large that it covers the lower part of the face like a
mask, and when folded back reaches down between the front legs. It is
in reality a grappling organ with hooks and spines for holding prey;
it is hinged in such a manner that it can be thrust out far beyond
the head to seize some insect, unsuspecting of danger. These nymphs
move so slowly and look so much like their background, that they are
always practically in ambush awaiting their victims.
[Illustration: _Nymph of a damsel-fly._
Outdoor Studies, Needham.]
The breathing of the dragon-fly nymphs is peculiar; there is an
enlargement of the rear end of the alimentary canal, in the walls of
which tracheæ or breathing tubes extend in all directions. The nymph
draws water into this cavity and then expels it, thus bathing the
tracheæ with the air mixed with water and purifying the air within
them. Expelling the water so forcibly, propels the nymph ahead, so
this act serves as a method of swimming as well as of breathing.
Damsel-fly larvæ, on the other hand, have at the rear end of the
body, three long, plate-like gills, each ramified with tracheæ.
[Illustration: _Nymph of a dragon-fly._
Seen from the side, showing the position of the great lower lip when
folded beneath the head.
From Outdoor Studies, Needham.]
Nymphs grow by shedding the skin as fast as it becomes too small; and
when finally ready to emerge, they crawl up on some object out of the
water, and molt for the last time, and are thereafter swift creatures
of the air.
_References_--American Insects, Kellogg. Comstock’s Manual.
LESSON LXXXV
THE DRAGON-FLIES AND DAMSEL-FLIES
_Leading thought_--The dragon-flies are among the swiftest of all
winged creatures and their rapid, darting flight enables them to
hawk their prey, which consists of other flying insects. Their
first stages are passed in the bottoms of ponds where they feed
voraciously on aquatic creatures. The dragon-flies are beneficial to
us because, when very young and when full grown, they feed largely
upon mosquitoes.
_Method_--The work of observing the habits of adult dragon-flies
should be largely done in the field during late summer and early
autumn. The points for observation should be given the pupils for
summer vacation use, and the results placed in the field note-book.
The nymphs may be studied in the spring, when getting material for
the aquarium. April and May are the best months for securing them.
They are collected by using a dip-net, and are found in the bottoms
of reedy ponds or along the edges of slow-flowing streams. These
nymphs are so voracious that they cannot be trusted in the aquarium
with other insects; each must be kept by itself. They may be fed by
placing other water insects in the aquarium with them or by giving
them pieces of fresh meat. In the latter case, tie the meat to a
thread so that it may be removed after a few hours, if not eaten,
since it soon renders the water foul.
The dragon-fly aquarium should have sand at the bottom and some water
weeds planted in it, and there should be some object in it which
extends above the surface of the water which the nymphs, when ready
to change to adults, can climb upon while they are shedding the last
nymphal skin, and spreading their new wings.
_Observations on the young of dragon-flies_--1. Where did you find
these insects? Were they at the bottom of the pond or along the edges
among the water weeds?
2. Are there any plume-like gills at the end of the body? If so, how
many? Are these plate-like gills used for swimming? If there are
three of these, which is the longer? Do you know whether the nymphs
with these long gills develop into dragon or into damsel-flies?
[Illustration: _Front view of the same nymph._
Outdoor Studies, Needham.]
[Illustration: _The same nymph seen from above._
Outdoor Studies, Needham.]
3. If there are no plume-like gills at the end of the body, how do
the insects move? Can they swim? What is the general color of the
body? Explain how this color protects them from observation? What
enemies does it protect them from?
4. Are the eyes large? Can you see the little wing-pads on the back
in which the wings are developing? Are the antennæ long?
5. Observe how the nymphs of both dragon and damsel-flies seize their
prey. Describe the great lower lip when extended for prey. How does
it look when folded up?
6. Can you see how a nymph without the plume-like gills breathes?
Notice if the water is drawn into the rear end of the body and then
expelled. Does this process help the insect in swimming?
7. When the dragon or damsel-fly nymph has reached its full growth,
where does it go to change to the winged form? How does this change
take place? Look on the rushes and reeds along the pond margin, and
see if you can find the empty nymph skins from which the adults
emerged. Where is the opening in them?
_Observations on the adult dragon-flies_--1. Catch a dragon-fly,
place it under a tumbler and see how it is fitted for life in the
air. Which is the widest part of its body? Note the size of the eyes
compared with the remainder of the head. Do they almost meet at the
top of the head? How far do they extend down the sides of the head?
Why does the dragon-fly need such large eyes? Why does a creature
with such eyes not need long antennæ? Can you see the dragon-fly’s
antennæ? Look with a lens at the little, swollen triangle between
the place where the two eyes join and the forehead; can you see the
little, simple eyes? Can you see the mouth-parts?
2. Next to the head, which is the widest and strongest part of the
body? Why does the thorax need to be so big and strong? Study the
wings. How do the hind wings differ in shape from the front wings?
How is the thin membrane of the wings made strong? Are the wings
spotted or colored? If so, how? Can you see if the wings are folded
along the front edges? Does this give strength to the part of the
wing which cuts the air? Take a piece of writing paper and see how
easily it bends; fold it two or three times like a fan and note
how much stiffer it is. Is it this principle which strengthens the
dragon-fly’s wings? Why do these wings need to be strong?
3. Is the dragon-fly’s abdomen as wide as the front part of the body?
What help is it to the insect when flying to have such a long abdomen?
_Outline for field notes_--Go to a pond or sluggish stream when the
sun is shining, preferably at midday, and note as far as possible the
following things:
1. Do you see dragon-flies darting over the pond? Describe their
flight. They are hunting flies and mosquitoes and other insects on
the wing; note how they do it. If the sky becomes cloudy, can you see
the dragon-flies hunting? In looking over a pond where there are many
dragon-flies darting about, do the larger species fly higher than the
smaller ones?
2. Note the way the dragon-flies hold their wings when they are
resting. Do they rest with their wings folded together over the
abdomen or are they extended out at an angle to the abdomen? Do
you know how this difference in attitude of resting determines one
difference between the damsel-flies and the dragon-flies?
3. The damsel-flies are those which hold their wings folded above
the back when resting. Are these as large and strong-bodied as the
dragon-flies? Are their bodies more brilliantly colored? How does the
shape of the head and eyes differ from those of the dragon-flies? How
many different colored damsel-flies can you find?
4. Do you see some dragon-flies dipping down in the water as they
fly? If so, they are laying their eggs. Note if you find others
clinging to reeds or other plants with the abdomen thrust below the
surface of the water. If so, these are inserting their eggs into the
stem of the plant.
_Supplementary reading_--Outdoor Studies, Needham, p. 54; “The Dragon
of Lagunita” in Insect Stories, Kellogg.
THE CADDIS-WORMS AND THE CADDIS-FLIES
_Teacher’s Story_
[Illustration: P]
People are to be pitied who have never tried to fathom the mysteries
of the bottom of brook or pond. Just to lie flat, face downward, and
watch for a time all that happens down there in that water world, is
far more interesting than witnessing any play ever given at matinee.
At first one sees nothing, since all the swift-moving creatures have
whisked out of sight, because they have learned to be shy of moving
shadows; but soon the crayfish thrusts out his boxing gloves from
some crevice, then a school of tiny minnows “stay their wavy bodies
’gainst the stream;” and then something strange happens! A bit of
rubbish on the bottom of the brook walks off. Perhaps it is a dream,
or we are under the enchantment of the water witches! But no, there
goes another, and now a little bundle of sand and pebbles takes unto
itself legs. These mysteries can only be solved with a dip-net and a
pail half filled with water, in which we may carry home the treasure
trove.
When we finally lodge our catch in the aquarium jar, our mysterious
moving sticks and stones resolve themselves into little houses built
in various fashions, and each containing one inmate. Some of the
houses are made of sticks fastened together lengthwise; some are
built like log cabins, crosswise; some consist simply of a hollow
stem cut a convenient length; and some are made of sand and pebbles,
and one, the liveliest of all, is a little tube made of bits of
rubbish and silk spun in a spiral, making a little cornucopia.
[Illustration: _Log cabin caddis-worms in their cases feeding upon a
water plant._
Photo by J. T. Lloyd.]
On the whole, the species which live in the log cabins are the most
convenient to study. Whatever the shape of the case or house, it has
a very tough lining of silk, which is smooth within, and forms the
framework to which the sticks and stones are fastened. These little
dwellings always have a front door and a back door. Out of the front
door may protrude the dark-colored head followed by two dark segments
and six perfectly active legs, the front pair being so much shorter
than the other two pairs that they look almost like mouth palpi. In
time of utter peace, more of the little hermit is thrust out and
we see the hind segment of the thorax which is whitish, and behind
this the abdomen of nine segments. At the sides of the abdomen, and
apparently between the segments, are little tassels of short, white
thread-like gills. These are filled with air, impure from contact
with the blood, and which exchanges its impurities speedily for the
oxygen from the air which is mixed with the water. Water is kept
flowing in at the front door of the cabin, over the gills and out at
the back door, by the rhythmic movement of the body of the little
hermit, and thus a supply of oxygen is steadily maintained.
[Illustration: _A caddis-fly._
Photo by J. T. Lloyd.]
The caddis-worm is not grown fast to its case as is the snail to its
shell. If we hold down with forceps a case in which the occupant is
wrong side up, after a few struggles to turn itself over, case and
all, it will turn over within the case. It keeps its hold upon the
case by two forward-curving hooks, one on each side of the tip of
the rear segment. These hooks are inserted in the tough silk and
hold fast. It also has on top of the first segment of the abdomen
a tubercle, which may be extended at will; this helps to brace
the larva in its stronghold, and also permits the water to flow
freely around the insect. So the little hermit is entrenched in
its cell at both ends. When the log-cabin species wishes to swim,
it pushes almost its entire body out of the case, thrusts back the
head, spreads the legs wide apart, and then doubles up, thus moving
through the water spasmodically, in a manner that reminds us of the
crayfish’s swimming except that the caddis-worm goes head first. This
log cabin species can turn its case over dexterously by movements of
its legs.
[Illustration: _A caddis-worm removed from its case._
Showing gills and the hooks on the last segment for holding fast to
the case.]
The front legs of the caddis-worm are so much shorter than the other
two pairs that they look like palpi, and their use is to hold close
to the jaws bits of food, which are being eaten. The other legs are
used for this too if the little legs cannot manage it; perhaps also
these short front legs help hold the bits of building material in
place while the web is woven to hold it there. The caddis-worm, like
the true caterpillars, has the opening of the silk gland near the
lower lip. The food of most caddis-worms is vegetable, usually the
various species of water plants; but there are some species which are
carnivorous, like the net-builder, which is a fisherman.
[Illustration: _Pupa of caddis-fly removed from its case. Note the
thread-like gills._
Photo by J. T. Lloyd.]
The caddis-worm case protects its inmate in two ways: First, from
the sight of the enemy, and second, from its jaws. A fish comes
along and sees a nice white worm and darts after it, only to find a
bundle of unappetizing sticks where the worm was. All of the hungry
predatory creatures of the pond and stream would be glad to get the
caddis-worm, if they knew where it went. Sometimes caddis-worm cases
have been found in the stomachs of fishes; perhaps they serve as fish
breakfast-food.
[Illustration: _Caddis-worm case fastened to leaf for pupation
period._
Photo by J. T. Lloyd.]
While it is difficult to see the exact operation of building the
caddis-worm house, the general proceeding may be readily observed.
Take a vigorous half-grown larva, tear off part of the sticks and
bits of leaves that make the log cabin, and then place the little
builder in a tumbler with half an inch of water at the bottom, in
which are many bright flower petals cut into strips, fit for caddis
lumber. In a few hours the little house will look like a blossom with
several rows of bright petals set around its doorway.
[Illustration: _Grating of silk over the door of a caddis-worm case
to protect the pupa._
Photomicrograph by J. T. Lloyd.]
When the caddis-worm gets ready to pupate, it fastens its case to
some object in the water and then closes its front and back doors.
Different species accomplish this in different ways; some spin and
fasten a silken covering over the doors; often this is in the form
of a pretty grating; others simply fasten the material of which the
case is made across the door. But though the door be shut, it is so
arranged as to allow the water to flow through and to bring oxygen
to the thread-like gills, which are on the pupæ as well as on the
larvæ. When ready to emerge, the pupa crawls out of its case and
climbs to some object above the water, sheds its pupa skin, and the
adult insect flies off. In some species, living in swift water, the
adult issues directly from the water, its wings expanding as soon as
touched by the air.
[Illustration: _Caddis-fly._
Photo by J. T. Lloyd.]
Caddis-flies are familiar to us all even if we do not know them
by name. They are night fliers and flame worshippers. Their
parchment-like or leathery wings are folded like a roof over the
back, and from the side the caddis-fly appears as an elongated
triangle with unequal sides. The front wings are long and the hind
ones shorter and wider; the antennæ are long and threadlike and
always waving about for impressions; the eyes are round and beadlike;
the tarsi, or feet, are long and these insects have an awkward way
of walking on the entire tarsus which gives them an appearance of
kneeling. Most of the species are dull-colored, brownish or gray, the
entire insect often being of one color. Caddis-flies would not be so
fond of burning themselves in lamps if they had the human sense of
smell, for the stench they make when scorching is nauseating. The
mother caddis-flies lay their eggs in the water. Perhaps some species
drop the eggs in when hovering above, but in some cases the insect
must make a diving bell of her wings and go down into the water to
place her eggs securely. The wings are covered with hairs and not
with scales, and therefore they are better fitted for diving than
would be those of the moth. I have seen caddis-flies swim vigorously.
_References_--Aquatic Insects, Miall; Manual for the Study of
Insects, Comstock.
[Illustration: _A spiral ribbon caddis-worm case. The inmate of this
case is a rapid swimmer._
Photo by J. T. Lloyd.]
[Illustration: _Case and caddis-worm._
Comstock’s Manual.]
LESSON LXXXVI
THE CADDIS-WORMS AND CADDIS-FLIES
_Leading thought_--The caddis-worms build around themselves little
houses out of bits of sticks, leaves or stones. They crawl about
on the bottom of the pond or stream, protected from sight, and
able to withdraw into their houses when attacked. The adult of the
caddis-worm is a winged moth-like creature which comes in numbers to
the light at night.
_Method_--With a dip-net the caddis-worms may be captured and then
may be placed in the school aquarium. Duckweed and other water plants
should be kept growing in the aquarium. The log cabin species is best
for this study, because it lives in stagnant water and will therefore
thrive in an aquarium.
_Observations_--1. Where do you find the caddis-worms? Can you see
them easily on the bottom of the stream or pond? Why?
2. Of what are the caddis-worm houses made? How many kinds have you
ever found? How many kinds of materials can you find on one case?
Describe one as exactly as possible. Find an empty case and describe
it inside. Why is it so smooth inside? How is it made so smooth? Are
all the cases the same size?
3. What does the caddis-worm do when it wishes to walk around? What
is the color of the head and the two segments back of it? What is the
color of the body? Why is this difference of color between the head
and body protective? Is the caddis-worm grown fast to its case, as
the turtle is to its shell?
4. Note the legs. Which is the shorter pair? How many pairs? What
is the use of the legs so much shorter than the others? If the
caddis-worm case happens to be wrong side up, how does it turn over?
5. When it wishes to come to the surface or swim, what does the
caddis-worm do? When reaching far out of its case does it ever lose
its hold? How does it hold on? Pull the caddis-worm out of its case
and see the hooks at the end of the body with which it holds fast.
6. How does the caddis-worm breathe? When it reaches far out of its
case, note the breathing gills. Describe them. Can you see how many
there are on the segments? How is the blood purified through these
gills?
7. What are the caddis-worm’s enemies? How does it escape them? Touch
one when it is walking, what does it do?
8. On top of the first segment of the abdomen is a tubercle. Do you
suppose that this helps to hold the caddis-worm in its case?
9. What does the caddis-worm eat? Describe how it acts when eating.
10. How does the caddis-worm build its case? Watch one when it makes
an addition to its case, and describe all that you can see.
11. Can you find any of the cases with the front and back doors
closed? How are they closed? Open one and see if there is a pupa
within it. Can you see the growing wings, antennæ and legs? Has it
breathing filaments like the larva? Cover the aquarium with mosquito
netting so as to get all the moths which emerge. See if you can
discover how the pupa changes into a caddis-fly.
12. How does the caddis-fly fold its wings? What is the general shape
of the insect when seen from the side with wings closed? What is the
texture of the wings? How many wings are there? Which pair is the
longer?
13. Describe the eyes. The antennæ. Does the caddis-fly walk on its
toes, or on its complete foot?
14. Examine the moths which come around the lights at night in the
spring and summer. Can you tell the caddis-flies from other insects?
Do they dash into the light? Do they seem anxious to burn themselves?
_Supplementary reading_--“A Little Fisherman,” Ways of the
Six-Footed, Comstock.
[Illustration: _Spiral case of caddis-worm made of small pebbles and
sand._
Comstock’s Manual.]
_Little brook, so simple so unassuming--and yet how many things
love thee!_
_Lo! Sun and Moon look down and glass themselves in thy
waters._
_And the trout balances itself hour-long against the stream,
watching for its prey; or retires under a stone to rest._
_And the water-rats nibble off the willow leaves and carry
them below the wave to their nests--or sit on a dry stone to
trim their whiskers._
_And the May-fly practices for the millionth time the miracle
of the resurrection, floating up an ungainly grub from the mud
below, and in an instant, in the twinkling of an eye (even
from the jaws of the baffled trout) emerging, an aerial fairy
with pearl-green wings._
_And the caddis-fly from its quaint disguise likewise emerges._
_And the prick-eared earth-people, the rabbits, in the stillness
of early morning play beside thee undisturbed, while the level
sunbeams yet grope through the dewy grass._
_And the squirrel on a tree-root--its tail stretched far
behind--leans forward to kiss thee,_
_Little brook, for so many things love thee._
EDWARD CARPENTER.
THE APHIDS, OR PLANT-LICE
_Teacher’s Story_
[Illustration: I]
I know of no more diverting occupation than watching a colony of
aphids through a lens; these insects are the most helpless and
amiable little ninnies in the whole insect world; and they look the
part, probably because their eyes, so large and wide apart, seem so
innocent and wondering. The usual color of aphids is green. As they
feed upon leaves, this color protects them from sight; but there are
many species which are otherwise colored, and some have most bizarre
and striking ornamentations. In looking along an infested leaf stalk,
we see them in all stages and positions. One may have thrust its beak
to the hilt in a plant stem, and is so satisfied and absorbed in
sucking the juice that its hind feet are lifted high in the air and
its antennæ curved backward, making altogether a gesture which seems
an adequate expression of bliss; another may conclude to seek a new
well, and pulls up its sucking tube, folding it back underneath the
body so it will be out of the way, and walks off slowly on its six
rather stiff legs; when thus moving, it thrusts the antennæ forward,
patting its pathway to insure safety. Perhaps this pathway may lead
over other aphids which are feeding, but this does not deter the
traveler nor turn it aside; over the backs of the obstructionists it
crawls, at which the disturbed ones kick the intruder with both hind
legs; it is not a vicious kick but a push rather, which says, “This
seat reserved, please!” It is comical to see a row of them sucking a
plant stem for “dear life,” the heads all in the same direction, and
they packed in and around each other as if there were no other plants
in the world to give them room, the little ones wedged in between the
big ones, until sometimes some of them are obliged to rest their hind
legs on the antennæ of the neighbors next behind.
[Illustration: _Perfect bliss!_]
[Illustration: _Aphids on plant._
Photo by Slingerland.]
Aphids are born for food for other creatures--they are simply little
machines for making sap into honey-dew, which they produce from the
alimentary canal for the delectation of ants; they are, in fact,
merely little animated drops of sap on legs. How helpless they are
when attacked by any one of their many enemies! All they do, when
they are seized, is to claw the air with their six impotent legs and
two antennæ, keeping up this performance as long as there is left
a leg, and apparently to the very last, never realizing “what is
doing.” But they are not without means of defence; those two little
tubes at the end of the body are not for ornament nor for producing
honey-dew for the ants, but for secreting at their tips a globule of
waxy substance meant to smear the eyes of the attacking insect. I
once saw an aphid perform this act, when confronted by a baby spider;
a drop of yellow liquid oozed out of one tube, and the aphid almost
stood on its head in order to thrust this offensive globule directly
into the face of the spider--the whole performance reminding me of
a boy who shakes his clenched fist in his opponent’s face and says,
“Smell of that!” The spider beat a hasty retreat.
A German scientist, Mr. Busgen, discovered that a plant-louse smeared
the eyes and jaws of its enemy, the aphis-lion, with this wax which
dried as soon as applied. In action it was something like throwing
a basin of paste at the head of the attacking party; the aphis-lion
thus treated, was obliged to stop and clean itself before it could
go on with its hunt, and the aphid walked off in safety. The aphids
surely need this protection because they have two fierce enemies,
the larvæ of the aphis-lions and of the ladybirds. They are also
the victims of parasitic insects; a tiny four-winged “fly” lays
an egg within an aphid; the larva hatching from it feeds upon the
inner portions of the aphid, causing it to swell as if afflicted
with dropsy. Later the aphid dies, and the interloper with malicious
impertinence cuts a neat circular door in the poor aphid’s skeleton
skin and issues from it a full fledged insect.
[Illustration: _A parasitized aphid enlarged, showing the door cut by
the parasite._]
The aphids are not without their resources to meet the exigencies of
their lives in colonies. There are several distinct forms in each
species, and they seem to be needed for the general good. During the
summer, we find most of the aphids on plants are without wings; these
are females which give birth to living young and do not lay eggs.
They do this until the plant is overstocked and the food supply seems
to be giving out, then another form is produced which has four wings.
These fly away to some other plant and start a colony there; but at
the approach of cold weather, or if the food plants give out, there
are male and female individuals developed, the females being always
wingless, and it is their office to lay the eggs which shall last
during the long winter months, when the living aphids must die for
lack of food plants. The next spring each winter-egg hatches into a
female which we call the “stem mother” since she with her descendants
will populate the entire plant.
[Illustration: _Winged and wingless forms of plant-lice._]
Plant-lice vary in their habits. Some live in the ground on the
roots of plants and are very destructive; but the greater number of
species live on the foliage of plants and are very fond of the young,
tender leaves and thus do great damage. Some aphids have their bodies
covered with white powder or with tiny fringes, which give them the
appearance of being covered with cotton.
The aphids injuring our flowers and plants may be killed by spraying
them with soapsuds made in the proportion of one-quarter pound of
ivory soap to one gallon of water. The spraying must be done very
thoroughly so as to reach all the aphids hidden on the stems and
beneath the leaves. It should be repeated every three days until the
aphids are destroyed.
LESSON LXXXVII
THE APHIDS, OR PLANT-LICE
_Leading thought_--Aphids have the mouth in the form of a sucking
tube which is thrust into the stems and leaves of plants; through it
the plant juices are drawn for nourishment. Aphids are the source of
honey-dew of which ants are fond.
_Method_--Bring into the schoolroom a plant infested with aphids,
place the stem in water and let the pupils examine the insects
through the lens.
_Observations_--1. How are the aphids settled on the leaf? Are their
heads in the same direction? What are they doing?
2. Touch one and make it move along. What does it do in order to
leave its place? What does it do with its sucking tube as it walks
off? On what part of the plant was it feeding? Why does not Paris
green when applied to the leaves of plants kill aphids?
3. Describe an aphid, including its eyes, antennæ, legs and tubes
upon the back. Does its color protect it from observation?
4. Can you see cast skins of aphids on the plant? Why does an aphid
have to shed its skin?
5. Are all the aphids on a plant wingless? When a plant becomes dry
are there, after several days, more winged aphids? Why do the aphids
need wings?
6. Do you know what honey-dew is? Have you ever seen it upon the
leaf? How is honey-dew made by the aphids? Does it come from the
tubes on their back? What insects feed upon this honey-dew?
7. What enemies have the aphids?
8. What damage do aphids do to plants? How can you clean plants of
plant-lice?
* * * * *
_I saw it_ (_an ant_), _at first, pass, without stopping, some
aphids which it did not however disturb. It shortly after
stationed itself near one of the smallest, and appeared to
caress it, by touching the extremity of its body, alternately
with its antennæ, with an extremely rapid movement. I saw,
with much surprise, the fluid proceed from the body of the
aphid, and the ant take it in its mouth. Its antennæ were
afterwards directed to a much larger aphid than the first,
which, on being caressed after the same manner, discharged
the nourishing fluid in greater quantity, which the ant
immediately swallowed: it then passed to a third which it
caressed, like the preceding, by giving it several gentle
blows, with the antennæ, on the posterior extremity of the
body; and the liquid was ejected at the same moment, and the
ant lapped it up._
PIERRE HUBER, 1810.
THE ANT-LION
_Teacher’s Story_
[Illustration: A]
A child is thrilled with fairy stories of ogres in their dens, with
the bones of their victims strewn around. The ants have real ogres,
but luckily, they do not know about it and so cannot suffer from
agonizing fears. The ant ogres seem to have depended upon the fact
that the ant is so absorbed in her work that she carries her booty
up hill and down dale with small regard for the topography of the
country. Thus they build their pits, with instinctive faith that they
will some day be entered by these creatures, obsessed by industry
and careless of what lies in the path. The pits vary with the size
of the ogre at the bottom; there are as many sized pits as are beds
in the story of Golden Locks and the bears; often the pits are not
more than an inch across, or even less, while others are two inches
in diameter. They are always made in sandy or crumbly soil and in a
place protected from wind and rain; they vary in depth in proportion
to their width, for the slope is always as steep as the soil will
stand without slipping.
All that can be seen of the ogre at the bottom, is a pair of long,
curved jaws, looking innocent enough at the very center of the pit.
If we dig the creature out, we find it a comical looking insect. It
is humpbacked, with a big, spindle-shaped abdomen; from its great
awkward body projects a flat, sneaking looking head, armed in front
with the sickle jaws which are spiny and bristly near the base, and
smooth, sharp and curved at the tip. The strange thing about these
jaws is that they lead directly to the throat, since the ant-lion has
no mouth. Each jaw is made up of two pieces which are grooved where
they join and thus form a tube with a hole in the tip through which
the industrious blood of the ants can be sucked; not only do the
sharp sickle points hold the victim, but there are three teeth along
the side of each jaw to help with this. The two front pairs of legs
are small and spiny; the hind legs are strong and peculiarly twisted,
and have a sharp spikelike claw at the end, which is so arranged as
to push the insect backward vigorously if occasion requires; in fact,
the ant-lion in walking about, moves more naturally backward than
forward because of the peculiar structure of his legs.
[Illustration: _Ant-lion with its cocoon and larva._
Comstock’s Manual.]
Having studied the ogre, we can see better how he manages to trap his
victim. As the ant goes scurrying along, she rushes over the edge of
the pit and at once begins to slide downward; she is frightened and
struggles to get back; just then a jet of sand, aimed well from the
bottom of the pit, hits her and knocks her back. She still struggles,
and there follows a fusillade of sand jets, each hitting her from
above and knocking her down to the fatal center where the sickle
jaws await her and are promptly thrust into her; if she is large and
still struggles, the big, unwieldy body of the ogre, buried in the
sand, anchors him fast and his peculiar, crooked hind legs push his
body backward in this strange tug of war; thus, the ant-ogre is not
dragged out of his den by the struggles of the ant, and soon the loss
of blood weakens her and she shrivels up.
The secret of the jets of sand, lies in the flat head of the ogre; if
we look at it regarding it as a shovel, we can see that it is well
fitted for its purpose; for it is a shovel with a strong mechanism
working it. In fact, the whole pit is dug with this shovel head.
Wonderful stories are told about the way that ant-lions dig their
pits, marking out the outer margin in a circle, and working inward.
However, our common ant-lion of the East simply digs down into the
sand and flips the sand out until it makes a pit. If an ant-lion can
be caught and put in a jar of sand it will soon make its pit, and the
process may be noted carefully.
There is one quality in the ogre which merits praise, and that is
his patience. There he lies in his hole for days or perhaps weeks,
with nothing to eat and no ant coming that way; so when we see an
absent-minded ant scrambling over into the pit, let us think of the
empty stomach of this patient little engineer which has constructed
his pit with such accuracy and so much labor. So precarious is the
living picked up by the ant-lions, that it may require one, two
or three years to bring one to maturity. At that time it makes a
perfectly globular cocoon of silk and sand, the size of a large
pea, and within it, changes to a pupa; and when finally ready to
emerge, the pupa pushes itself part way out of the cocoon and the
skin is shed and left at the cocoon door. The adult resembles a small
dragon-fly; it has large net-veined wings and is a most graceful
insect, as different as can be from the humpbacked ogre which it once
was--a transformation quite as marvelous as that which occurred in
Beauty and the Beast. Throughout the Middle West, the ant-lion in its
pit is called the “doodle-bug.”
_Reference_--Manual for Study of Insects, Comstock.
LESSON LXXXVIII
THE ANT-LION
_Leading thought_--The ant-lion, or “doodle-bug” makes a little
pit in the sand with very steep sides, and hidden at the bottom of
it, waits for ants to tumble in to be seized by its waiting jaws.
Later the ant-lion changes to a beautiful insect with gauzy wings,
resembling a small dragon-fly.
_Method_--The pupils should see the ant-lion pits in their natural
situations, but the insects may be studied in the schoolroom. Some
of the ant-lions may be dug out of their pits and placed in a dish
of sand. They will soon make their pits, and may be watched during
this interesting process. It is hardly advisable to try to rear these
insects, as they may require two or three years for development.
_Observations_--1. Where were the ant-lion pits out of doors? Were
they in a windy place? Were they in a place protected from storms? In
what kind of soil were they made?
2. Measure one of the pits. How broad across, and how deep? Are all
the pits of the same size? Why?
3. What can you see as you look down into the ant-lion’s pit? Roll
a tiny pebble in and see what happens? Watch until an ant comes
hurrying along and slips into the pit. What happens then? As she
struggles to get out how is she knocked back in? What happens to her
if she falls to the bottom?
4. Take a trowel and dig out the doodle-bug. What is the shape of its
body? What part of the insect did you see at the bottom of the pit?
Do you know that these great sickle-shaped jaws are hollow tubes for
sucking blood? Does the ant-lion eat anything except the blood of its
victim?
5. Can you see that the ant-lion moves backward more easily than
forward? How are its hind legs formed to help push it backward? How
does this help the ant-lion in holding its prey? How does the big
awkward body of the ant-lion help to hold it in place at the bottom
of the pit when it seizes an ant in its jaws?
6. What shape is the ant-lion’s head? How does it use this head in
taking its prey? In digging its pit?
7. Take a doodle-bug to the schoolroom, place it in a dish of sand,
covered with glass, and watch it build its pit.
8. Read in the entomological books about the cocoon of the
ant-lion and what the adult looks like, and then write an ant-lion
autobiography.
_Supplementary reading_--Insect Stories, Kellogg, “The True Story of
Morrowbie Jukes.”
THE MOTHER LACE-WING AND THE APHIS-LION
_Teacher’s Story_
[Illustration: F]
Flitting leisurely through the air on her green gauze wings, the
lace-wing seems like a filmy leaf, broken loose and drifting on the
breeze. But there is purpose in her flight, and through some instinct
she is enabled to seek out an aphis-ridden plant or tree, to which
she comes as a friend in need. As she alights upon a leaf, she is
scarcely discernible because of the pale green of her delicate body
and wings; however, her great globular eyes that shine like gold
attract the attention of the careful observer. But though she is so
fairy-like in appearance, if you pick her up, you will be sorry if
your sense of smell is keen, for she exhales a most disagreeable odor
when disturbed--a habit which probably protects her from birds or
other creatures which might otherwise eat her.
However, if we watch her we shall see that she is a canny creature
despite her frivolous appearance; her actions are surely peculiar. A
drop of sticky fluid issues from the tip of her body, and she presses
it down on the surface of the leaf; then lifting up her slender
abdomen like a distaff, she spins the drop into a thread a half inch
long or more, which the air soon dries; and this silken thread is
stiff enough to sustain an oblong egg, as large as the point of a
pin, which she lays at the very tip of it. This done she lays another
egg in a like manner, and when she is through, the leaf looks as if
it were covered with spore cases of a glittering white mold. This
done she flies off and disports herself in the sunshine, care free,
knowing that she has done all she can for her family.
[Illustration: _Aphis-lion, eggs, larva, cocoon and the adult, lace
wing._
Comstock’s Manual.]
After a few days the eggs begin to look dark, and then if we examine
them with a lens, we may detect that they contain little doubled-up
creatures. The first we see of the egg inmate as it hatches, is a
pair of jaws thrust through the shell, opening it for a peep-hole; a
little later the owner of the jaws, after resting a while with an eye
on the world which he is so soon to enter, pushes out his head and
legs and drags out a tiny, long body, very callow-looking and clothed
in long, soft hairs. At first the little creature crawls about his
egg-shell, clinging tightly with all his six claws, as if fearful of
such a dizzy height above his green floor; then he squirms around a
little and thrusts out a head inquiringly while still hanging on “for
dear life.” Finally he gains courage and prospects around until he
discovers his egg stalk, and then begins a rope climbing performance,
rather difficult for a little chap not more than ten minutes old. He
takes a careful hold with his front claws, the two other pairs of
legs carefully balancing for a second, and then desperately seizing
the stalk with all his clasping claws, and with many new grips and
panics, he finally achieves the bottom in safety. As if dazed by
his good luck, he stands still for a time, trying to make up his
mind what has happened and what to do next; he settles the matter
by trotting off to make his first breakfast of aphids; and now we
can see that it is a lucky thing for his brothers and sisters, still
unhatched, that they are high above his head and out of reach, for
he might not be discriminating in the matter of his breakfast food,
never having met any of his family before. He is a queer looking
little insect, spindle-shaped and with peculiarly long, sickle-shaped
jaws projecting from his head. Each of these jaws is made up of two
pieces joined lengthwise so as to make a hollow tube, which has an
opening at the tip of the jaw, and another one at the base which
leads directly to the little lion’s throat. Watch him as he catches
an aphid; seizing the stupid little bag of sap in his great pincers,
he lifts it high in the air, as if drinking a bumper, and sucks its
green blood until it shrivels up, kicking a remonstrating leg to the
last. It is my conviction that aphids never realize when they are
being eaten; they simply dimly wonder what is happening.
It takes a great many aphids to keep an aphis-lion nourished until
he gets his growth; he grows like any other insect by shedding his
skeleton skin when it becomes too tight. Finally he doubles up and
spins around himself a cocoon of glistening white silk, leaving
it fastened to the leaf; when it is finished, it looks like a
seed pearl, round and polished. I wish some child would watch an
aphis-lion weave its cocoon and tell us how it is done! After a time,
a week or two perhaps, a round little hole is cut in the cocoon,
and there issues from it a lively little green pupa, with wing
pads on its back; but he very soon sheds his pupa skin and issues
as a beautiful lace-wing fly with golden eyes and large, filmy,
iridescent, pale green wings.
LESSON LXXXIX
THE MOTHER LACE-WING AND THE APHIS-LION
_Leading thought_--The lace-wing fly or golden-eyes, as she is
called, is the mother of the aphis-lion. She lays her eggs on the top
of stiff, silken stalks. The young aphis-lions when hatched, clamber
down upon the leaf and feed upon plant-lice, sucking their blood
through their tubular jaws.
_Method_--Through July and until frost, the aphis-lions may be found
on almost any plant infested with plant-lice; and the lace-wing’s
eggs or egg-shells on the long stalks are also readily found.
All these may be brought to the schoolroom. Place the stem of a
plant infested with aphids in a jar of water, and the acts of the
aphis-lions as well as the habits of the aphids may be observed
during recess or at other convenient times, by all the pupils.
_Observations_--1. When you see a leaf with some white mold upon it,
examine it with a lens; the mold is likely to be the eggs of the
lace-wing. Is the egg as large as a pin head? What is its shape?
What is its color? How long is the stalk on which it is placed? Of
what material do you think the stalk is made? Why do you suppose the
lace-wing mother lays her eggs on the tips of stalks? Are there any
of these eggs near each other on the leaf?
2. If the egg is not empty, observe through a lens how the young
aphis-lion breaks its egg-shell and climbs down.
3. Watch an aphis-lion among the plant-lice. How does it act? Do the
aphids seem afraid? Does the aphis-lion move rapidly? How does it act
when eating an aphid?
4. What is the general shape of the aphis-lion? Describe the jaws. Do
you think these jaws are used for chewing, or merely as tubes through
which the green blood of the aphids is sucked? Do the aphis-lions
ever attack each other or other insects? How does the aphis-lion
differ in appearance from the ladybird larva?
5. What happens to the aphis-lion after it gets its growth? Describe
its cocoon if you can find one.
6. Describe the little lace-wing fly that comes from the cocoon. Why
is she called, golden-eyes? Why lace-wing? Does she fly rapidly? Do
you suppose that if she should lay her eggs flat on a leaf, that the
first aphis-lion that hatched would run about and eat all its little
brothers and sisters which were still in their egg-shells? How do the
aphis-lions benefit our rose bushes and other cultivated plants?
_Supplementary Reading_--“A Tactful Mother” in Ways of the Six-Footed.
THE MOSQUITO
_Teacher’s Story_
[Illustration: I]
In defiance of the adage, the mother of our most common mosquitoes
does not hesitate to put her eggs all in one basket, but perhaps she
knows it is about the safest little basket for eggs in this world
of uncertainties. If it were possible to begin this lesson with the
little boat-shaped egg baskets, I should advise it. They may be found
in almost any rain barrel, and the eggs look like a lot of tiny
cartridges set side by side, points up, and lashed or glued together,
so there shall be no spilling. Like a certain famous soap, they
“float,” coming up as dry as varnished corks when water is poured
upon them.
[Illustration: _The egg-raft of a mosquito enlarged._]
[Illustration: _A mosquito aquarium._]