Chapter XXVI: Part II: Animal Life (19)

Drawn by Evelyn Mitchell.]

In the North, our greatest danger is from the mosquitoes which carry the malarial germs, and these are the mosquitoes with spotted wings and belong to the genus Anopheles. This mosquito, in order to be of danger to us must first feed upon the blood of some person suffering from malaria (ague) and thus take the germ of the disease into its stomach. Here the germ develops and multiplies into many minute germs, which pass through another stage and finally get into the blood of the mosquito and accumulate in the salivary glands. The reason any mosquito bite or insect bite swells and itches is because, as the insect’s beak is inserted into the flesh, it carries with it some of the saliva from the insect’s mouth. In the case of Anopheles these malarial germs are carried with the saliva into the blood of the victim. It has been proven that in the most malarial countries, like Italy and India, people are entirely free from malaria if they are not bitten by mosquitoes.

After this explanation has been made, it would be well for the teacher to take the pupils on a tour of inspection through the neighborhood to see if there are any mosquito larvæ in rain barrels, ponds or pools of stagnant water. If such places are found, let the pupils themselves apply the following remedies:

1. Rain barrels should be securely covered.

2. All stagnant pools should be drained and filled up if possible.

3. Wherever there are ponds or pools where mosquitoes breed that cannot be filled or drained, the surface of the water should be covered with a spray of kerosene oil. This may be applied with a spray pump or from a watering can.

4. If it is impracticable to cover such places with oil, introduce into such pools the following fish: Minnows, sticklebacks, sunfish and goldfish.

The effect of this lesson upon the children should be to impress them with the danger to life and health from mosquitoes and to implant in them a determination to rid the premises about their homes of these pests.

_References_--Farmers’ Bulletin No. 155, U. S. Department of Agriculture, by L. O. Howard; leaflet in Reading Course for Farmers’ Wives, series 2, No. 10, by M. V. Slingerland; American Insects, Kellogg; The Insect Book, Howard; Insect Life, The Manual for the Study of Insects, Comstock; Ways of the Six-Footed, Comstock.

Comstock’s Manual.]

LESSON XC

THE MOSQUITO

_Leading thought_--The wrigglers, or wigglers, which we find in rain-barrels and stagnant water are the larvæ of mosquitoes. We should study their life history carefully if we would know how to get rid of mosquitoes.

_Method_--There is no better way to interest the pupils in mosquitoes than to place in an aquarium jar in the schoolroom a family of wrigglers from some pond or rain barrel. For the pupils’ personal observation, take some of the wrigglers from the aquarium with a pipette and place them in a homeopathic vial; fill the vial three-fourths full of water and cork it. Pass it around with a hand lens and give each pupil the opportunity to observe it for five or ten minutes. It would be well if this vial could be left on each desk for an hour or so during study periods, so that the observations may be made casually and leisurely. While the pupils are studying the wrigglers, the following questions should be placed upon the blackboard, and each pupil should make notes which may finally be given at a lesson period. This is particularly available work for September.

In studying the adult mosquito, a lens or microscope is necessary. But it is of great importance that the pupils be taught to discriminate between the comparatively harmless species of Culex and the dangerous Anopheles and therefore they should be taught to be observant of the way mosquitoes rest upon the walls, and whether they have mottled or clear wings.

_The Larva_

_Observations_: 1. Note if all the wrigglers are of the same general shape, or if some of them have a very large head; these latter are the pupæ and the former are the larvæ. We will study the larvæ first. Where do they rest when undisturbed? Do they rest head up or down? Is there any part of their body that comes to the surface of the water?

2. When disturbed what do they do? When they swim, do they go head or tail first? When they float do they go upward or downward?

3. Observe one resting at the top. At what angle does it hold itself to the surface of the water? Observe its head. Can you see the jaw brushes revolving rapidly? What is the purpose of this? Describe its eyes. Can you see its antennæ?

4. Note the two peculiar tubes at the end of the body and see if you can make out their use.

5. Note especially the tube that is thrust up to the surface of the water when the creatures are resting. Can you see how the opening of this tube helps to keep the wriggler afloat? What do you think is the purpose of this tube? Why does it not become filled with water when the wriggler is swimming? Can you see the two air vessels, or trachæ, extending from this tube along the back the whole length of the body?

6. Note the peculiarities of the other tube at the rear end of the body. Do you think the little finger-like projections are an aid in swimming? How many are there?

7. Can you see the long hairs along the side of the body?

8. Does the mosquito rest at the bottom of the bottle or aquarium?

_The Pupa_

9. What is the most noticeable difference in appearance between the larva and pupa?

10. When the pupa rests at the surface of the water, is it the same end up as the wriggler?

11. Note on the “head” of the pupa two little tubes extending up like ears. These are the breathing tubes. Note if these open to the air when the pupa rests at the surface of the water.

12. Can you see the swimming organs at the rear of the body of the pupa? Does the pupa spend a longer time resting at the surface than the larva? How does it act differently from the pupæ of other flies and moths and butterflies?

13. How does the mosquito emerge from the pupa skin? Why does kerosene oil poured on the surface of the water kill mosquitoes?

_The Adult Mosquito_

1. Has the mosquito feathery antennæ extending out in front? If so, what kind of mosquitoes are such?

2. Do the mosquitoes with bushy antennæ bite? Do they sing?

3. Are the wings of the mosquito spotted or plain? How many has it?

4. When at rest, is it shortened and humpbacked or does it stand straight out with perhaps its hind legs in the air?

5. What are the characteristics by which you can tell the dangerous Anopheles?

6. Why is the Anopheles more dangerous than the Culex?

7. Examine a mosquito’s wing under a microscope and describe it.

8. Examine the antennæ of a male and a female mosquito under a microscope, and describe the difference.

9. Which sex of the mosquito does the biting and the singing?

10. How is the singing done?

THE HOUSE-FLY

_Teacher’s Story_

The house-fly is surely an up-to-date member of that select class which evolutionists call the “fit.” It flourishes in every land, plumping itself down in front of us at table, whether we be eating rice in Hong Kong, dhura in Egypt, macaroni in Italy, pie in America, or tamales in Mexico. There it sits, impertinent and imperturbable, taking its toll, letting down its long elephant-trunk tongue, rasping and sucking up such of our meal as fits its needs. As long as we simply knew it as a thief we, during untold ages, merely slapped it and shooed it, which effort on our part apparently gave it exhilarating exercise. But during recent years we have begun trapping and poisoning, trying to match our brains against its agility; although we slay it by thousands, we seem only to make more room for its well-fed progeny of the future, and in the end we seem to have gained nothing. But the most recent discoveries of science have revealed to us, that what the house-fly takes of our food, is of little consequence to what it leaves behind. Because of this, we have girded up our loins and gone into battle in earnest.

I have always held that nature-study should follow its own peaceful path and not be the slave of economic science. But occasionally it seems necessary, when it is a question of creating public sentiment, and of cultivating public intelligence in combating a great peril, to make nature-study a handmaiden, if not a slave, in this work. If our woods were filled with wolves and bears, as they were in the days of my grandfather, I should give nature-study lessons on these animals, which would lead to their subjugation. Bears and wolves trouble us no more; but now we have enemies far more subtle, in the ever-present microbes, which we may never hope to conquer but which, with proper precautions, we may render comparatively harmless. Thus, our nature-study with insects which carry disease, like the mosquitoes, flies and fleas, must be a reconnaissance for a war of extermination; the fighting tactics may be given in lessons on health and hygiene.

Perhaps if a fly were less wonderfully made, it would be a less convenient vehicle for microbes. Its eyes are two great, brown spheres on either side of the head, and are composed of thousands of tiny six-sided eyes that give information of what is coming in any direction; in addition, it has on top of the head, looking straight up, three tiny, shining, simple eyes, which cannot be seen without a lens. Its antennæ are peculiar in shape, but are evidently sense organs; it is attracted from afar by certain odors, and so far as we can discover, its antennæ are all the nose it has. Its mouth-parts are all combined to make a most amazing and efficient organ for getting food; at the tip are two flaps, which can rasp a substance so as to set free the juices, and above this is a tube, through which the juices may be drawn to the stomach. This tube is extensible, being conveniently jointed so that it can be folded under the “chin” when not in use. This is usually called the fly’s tongue, but it is really all the mouth parts combined, as if a boy had his lips, teeth and tongue, standing out from his face, at the end of a tube a foot long.

The thorax can be easily studied; it is striped black and white above and bears the two wings, and the two little flaps that are called balancers and which are probably remnants of hind wings which the remote ancestors of flies flew with. The fly’s wing is a transparent but strong membrane strengthened by veins, and is prettily iridescent. The thorax bears on its lower side the six pairs of legs. The abdomen consists of five segments and is covered with stiff hairs. The parts of the leg, seen when the fly is walking, consists of three segments, the last segment or tarsus being more slender, and if looked at with a lens, is seen to be composed of five segments, the last of which bears the claws; it is with these claws that the fly walks, although all of the five segments really form the foot; in other words, it walks on its tip-toes. But it clings to ceilings by means of the two little pads below the claws, which are covered with hairs that excrete at the tips, a sticky fluid. Because of the hairs on its feet, the fly becomes a carrier of microbes and a menace to health.

The greatest grudge I have against this little, persistent companion of our household is the way it has misled us by appearing to be so fastidious in its personal habits. We have all of us seen, with curiosity and admiration, its complex ablutions and brushings. It usually begins, logically, with its front feet, the hands; these it cleans by rubbing them against each other lengthwise. The hairs and spines on one leg act as a brush for the other, and then lest they be not clean, it nibbles them with its rasping disc, which is all the teeth it has. It then cleans its head with these clean hands, rubbing them over its big eyes with a vigor that makes us wink simply to contemplate; then bobbing its head down so as to reach what is literally its back hair, it brushes valiantly. After this is done, it reaches forward first one and then the other foot of the middle pair of legs, and taking each in turn between the front feet, brushes it vigorously, and maybe nibbles it. But as a pair of military brushes, its hind feet are conspicuously efficient; they clean each other by being rubbed together and then they work simultaneously on each side in cleaning the wings, first the under side and then the upper side. Then over they come and comb the top of the thorax; then they brush the sides, top and under sides of the abdomen, cleaning each other between the acts. Who, after witnessing all this, could believe that the fly could leave any tracks on our food, which would lead to our undoing! But the house-fly, like many housekeepers with the best intentions in the matter of keeping clean, has not mastered the art of getting rid of the microbes. Although it has so many little eyes, none of them can magnify a germ so as to make it visible; and thus it is that, when feeding around where there have been cases of typhoid and other enteric diseases, the house-fly’s little claws become infested with disease germs; and when it stops some day to clean up on our table, it leaves the germs with us. Thus our only safety lies in the final extermination of this little nuisance.

It is astonishing how few people know about the growth of flies. People of the highest intelligence in other matters, think that a small fly can grow into a large one. A fly, when it comes from the pupa stage, is as large as it will ever be, the young stages of flies being maggots. The house-fly’s eggs are little, white, elongated bodies about as large as the point of a pin. These are laid preferably in horse manure. After a few hours, they hatch into slender, pointed, white maggots which feed upon the excrement. After five or six days, the larval skin thickens, turns brown, making the insect look like a small grain of wheat. This is the pupal stage, which lasts about five days, and then the skin bursts open and the full-grown fly appears. Of course, not all the flies multiply according to the example given to the children. The house-fly has many enemies and, therefore, probably no one hibernating mother fly is the ancestress of billions by September; however, despite enemies, flies multiply with great rapidity.

I know of no more convincing experiment as an example of the dangerous trail of the fly, than that of letting a house-fly walk over a saucer of nutrient gelatin. After three or four days, each track is plainly visible as a little white growth of bacteria.

Much is being done now to eradicate the house-fly, and undoubtedly there will be new methods of fighting it devised every year. The teacher should keep in touch with the bulletins on this subject published by the United States Department of Agriculture, and should give the pupils instructions according to the latest ideas. At present the following are the methods of fighting this pest: Keep the stable clean and place the manure under cover. All of the windows of the house should be well screened. All the flies which get into the house should be killed by using the commercial fly papers.

LESSON XCI

THE HOUSE-FLY

_Leading thought_--The house-fly has conquered the world and is found everywhere. It breeds in filth and especially in horse manure. It is very prolific; the few flies that manage to pass the winter in this northern climate, are ancestors of the millions which attack us and our food later in the season. These are a menace to health because they carry germs of disease from sputa and excrementitious matter to our tables, leaving them upon our food.

_Method_--Give out the questions for observation and let the pupils answer them either orally or in their note-books. If possible, every pupil should look at a house-fly through a three-quarters objective. If this is not possible, pictures should be shown to demonstrate its appearance.

_Observations_--1. Look at a fly, using a lens if you have one. Describe its eyes. Do you see that they have a honeycomb arrangement of little eyes? Can you see, on top of the head between the big eyes, a dot? A microscope reveals this dot to be made of three tiny eyes, huddled together. After seeing a fly’s eyes, do you wonder that you have so much difficulty in hitting it or catching it?

2. Can you see the fly’s antennæ? Do you think that it has a keen sense of smell? Why?

3. How many wings has the fly? How does it differ from the bee in this respect? Can you see two little white objects, one just behind the base of each wing? These are called poisers, or balancers, and all flies have them in some form. What is the color of the wings? Are they transparent? Can you see the veins in them? On what part of the body do the wings grow?

4. Look at the fly from below. How many legs has it? From what part of the body do the legs come? What is that part of the insect’s body called, to which the legs and wings are attached?

5. How does the fly’s abdomen look? What is its color and its covering?

6. Look at the fly’s legs. How many segments can you see in a leg? Can you see that the segment on which the fly walks has several joints? Does it walk on all of these segments or on the one at the tip?

7. When the fly eats, can you see its tongue? Can you feel its tongue when it rasps your hand? Where does it keep its tongue usually?

8. Describe how a fly makes its toilet as follows: How does it clean its front feet? Its head? Its middle feet? Its hind feet? Its wings?

9. Do you know how flies carry disease? Did you ever see them making their toilet on your food at the table? Do you know what diseases are carried by flies? What must you do to prevent flies from bringing disease to your family?

10. Do you think that a small fly ever grows to be a large fly? How do the young of all kinds of flies look? Do you know where the house-fly lays its eggs? On what do the maggots feed? How long before they change to pupæ? How long does it take them to grow from eggs to flies? How do the house-flies in our northern climate pass the winter?

11. _Lesson in Arithmetic_--It requires perhaps twenty days to span the time from the eggs of one generation of the house-fly to the eggs of the next, and thus there might easily be five generations in one summer. Supposing the fly which wintered behind the window curtain in your home last winter, flew out to the stables about May 1st and laid 120 eggs in the sweepings from the horse stable, all of which hatched and matured. Supposing one-half of these were mother flies and each of them, in turn, laid 120 eggs, and so on for five generations, all eggs laid developing into flies, and one-half of the flies of each generation being mother flies. How many flies would the fly that wintered behind your curtain have produced by September?

12. Pour some gelatin unsweetened, on a clean plate. Let a house-fly walk around on the gelatin as soon as it is cool; cover the plate to keep out the dust and leave it for two or three days. Examine it then and see if you can tell where the fly walked. What did it leave in its tracks?

13. Write an essay on the house-fly, its dangers and how to combat it, basing the essay on Bulletins of the U. S. Department of Agriculture.

THE COLORADO POTATO-BEETLE

_Teacher’s Story_

The potato-beetle is not a very attractive insect, but it has many interesting peculiarities. No other common insect so clearly illustrates the advantage of warning colors. If we take a beetle in the hand, it at first promptly falls upon its back, folds its legs, and antennæ down close to its body, and “plays possum” in a very canny manner. But if we squeeze it a little, immediately an orange-red liquid is ejected on the hand, and a very ill-smelling liquid it is. If we press lightly, only a little of the secretion is thrown off; but if we squeeze harder it flows copiously. Thus a bird trying to swallow one of these beetles, would surely get a large dose. The liquid is very distasteful to birds, and it is indeed a stupid bird that does not soon learn to let severely alone orange and yellow beetles, striped with black. The source of this offensive and defensive juice is at first a mystery, but if we observe closely we can see it issuing along the hind edge of the thorax and the front portion of the wing-covers; the glands in these situations secrete the protective juice as it is needed. The larvæ are also equipped with similar glands and, therefore, have the brazen habit of eating the leaves of our precious potatoes without attempting to hide. They seem to know that they are far safer when seen by birds than when concealed from them.

The life history of the potato-beetle is briefly as follows: Some of the adult beetles or pupæ winter beneath the surface of the soil, burrowing down a foot or more to escape freezing. As soon as the potato plants appear above ground the mother beetle comes out and lays her eggs upon the under sides of the leaves. These orange-yellow eggs are usually laid in clusters. In about a week there hatches from the eggs little yellow or orange humpbacked larvæ, which begin at once to feed upon the leaves. These larvæ grow as do other insects, by shedding their skins. They do this four times, and during the last stages, are very conspicuous insects on the green leaves; they are orange or yellow with black dots along the sides, and so humpbacked are they that they seem to be “gathered with a puckering string” along the lower side. It requires from sixteen days to three weeks for a larva to complete its growth. It then descends into the earth and forms a little cell in which it changes to a pupa. It remains in this condition for one or two weeks, according to the temperature, and then the full-fledged beetle appears. The entire life cycle from egg to adult beetle may be passed in about a month, although if the weather is cold, this period will be longer. The beetles are very prolific, a mother beetle having been known to produce five hundred eggs, and there are two generations each year. These beetles not only damage the potato crop by stopping the growth through destroying the leaves, but they also cause the potatoes to be of inferior quality.

Photo by Slingerland.]

The adult beetle is an excellent object lesson in the study of beetle form. Attention should be called to the three regions of the body: A head which is bright orange; the compound eyes, which are black; and three simple eyes on the top of the head, which are difficult to see without a lens. The antennæ are short, their joints easily noted, and special attention should be paid to their use, for they are constantly moving to feel approaching objects. The two pairs of mouth palpi may be seen, and the beetle will eagerly eat raw potatoes, so that the pupils may see that it has biting mouth-parts. The thoracic shield is orange, ornamented with black. The three pairs of legs are short, which is a proof that these beetles do not migrate on foot. The claws and the pads beneath can be seen with the naked eye. Each wing-cover bears five yellow stripes, also five black ones, although the outside black stripe is rather narrow. These beetles are very successful flyers. During flight, the wing-covers are raised and held motionless while the gauzy wings beneath are unfolded and do the work. Children are always interested in seeing the way the beetles fold their wings beneath the wing-covers.

Photo by Slingerland.]

Photo by Slingerland.]

One of the most remarkable things about the Colorado potato-beetle is its history. It is one of the few insect pests which is native to America. It formerly fed upon sandbur, a wild plant allied to the potato, which grows in the region of Colorado, Arizona and Mexico, and was a well behaved, harmless insect. With the advance of civilization westward, the potato came also, and proved to be an acceptable plant to this insect; and here we have an example of what an unlimited food supply will do for an insect species. The beetles multiplied so much faster than their parasites, that it seemed at one time as if they would conquer the earth by moving on from potato field to potato field. They started on their march to the Atlantic seaboard in 1859; in 1874, they reached the coast and judging by the numbers washed ashore, they sought to fly or swim across the Atlantic. By 1879, they had spread over an area consisting of more than one-third of the United States.

_Reference_--The Colorado Potato-Beetle, Chittenden, Bulletin of U. S. Department of Agriculture.

LESSON XCII

THE COLORADO POTATO-BEETLE

_Leading thought_--The Colorado potato-beetle is a very important insect, since it affects the price of potatoes each year. It is disagreeable as a food for birds, because of an acrid juice which it secretes. We should learn its life-history and thus be able to deal with it intelligently in preventing its ravages.

_Method_--The study of the potato-beetle naturally follows and belongs to gardening. The larvæ should be brought into the schoolroom and placed in a breeding cage on leaves of the potato vine. Other plants may be put into the cage to prove that these insects will only eat the potato. The children should observe how the larvæ eat and how many leaves a full grown larva will destroy in a day. Earth should be put in the bottom of the breeding cage so that the children may see the larvæ descend and burrow into it. The adult beetles should be studied carefully, and especially, the children should see the excretion of the acrid juice.

_Observations_--1. At what time do you see the potato-beetles? Why are they more numerous in the fall than in the spring? Where do those which we find in the spring come from? What will they do if they are allowed to live?

2. What is the shape of the potato-beetle? Describe the markings on its head. What color are its eyes? Describe its antennæ. How are they constantly used? Can you see the palpi of the mouth? Give the beetle a bit of potato and note how it eats.

3. What is the color of the shield of the thorax? Describe the legs. Do you think the beetle can run fast? Why not? How many segments has the foot? Describe the claws. Describe how it clings to the sides of a tumbler or bottle.

Photo by Slingerland.]

4. If the beetle cannot run rapidly, how does it travel? Describe the wing-covers. Why is this insect called the ten-lined potato beetle?

5. Describe the wings. How are they folded when at rest? How are the wing-covers carried when the beetle is flying?

6. Take a beetle in your hand. What does it do? Of what advantage is it to the insect to pretend that it is dead? If you squeeze the beetle what happens? How does the fluid which it ejects look and smell? Try and discover where this fluid comes from? Of what use is it to the beetle? Why will birds not eat the potato-beetle?

7. Where does the mother beetle lay her eggs? Are they laid singly or in clusters? What color are the eggs? How long after they are laid before they hatch?

8. Describe the young larva when it first hatches. What color is it at first? Does it change color later? Describe the colors and markings of a full grown larva.

9. How does this larva injure the potato vines? Does it remain in sight while it is feeding? Does it act as if it were afraid of birds? Why is it not eaten by birds?

10. Where does the larva go when it is full grown? How many times does it shed its skin during its growth? Does it make a little cell in the ground? How does the pupa look? Can you see in it the eyes, antennæ, legs and wings of the beetle?

11. Write an English theme giving the history of the Colorado potato-beetle, and the reasons for its migration from its native place.

THE LADYBIRD

_Teacher’s Story_

_Ladybird, Ladybird, fly away home!
Your house is on fire, your children are burning._

This incantation we, as children, repeated to this unhearing little beetle, probably because she is and ever has been, the incarnation of energetic indecision. She runs as fast as her short legs can carry her in one direction, as if her life depended on getting there, then she turns about and goes with quite as much vim in another direction. Thus, it is no wonder the children think that when she hears this news of her domestic disasters, she wheels about and starts for home; but she has not any home now nor did she ever have a home, and she does not carry even a trunk. Perhaps it would be truer to say that she has a home everywhere, whether she is cuddled under a leaf for a night’s lodging or industriously climbing out on twigs, only to scramble back again, or perchance to take flight from their tips.

There are many species of ladybirds, but in general they all resemble a tiny pill cut in half, with legs attached to the flat side. Sometimes it may be a round and sometimes an oval pill, but it is always shining and the colors are always dull dark red, or yellow, or whitish, and black. Sometimes she is black with red or yellow spots, sometimes red or yellow with black spots and the spots are usually on either side of the thorax and one on each snug little wing-cover. But if we look at the ladybird carefully we can see the head and the short, clublike antennæ. Behind the head is the thorax with its shield, broadening toward the rear, spotted and ornamented in various ways; the head and thorax together occupy scarcely a fourth of the length of the insect, and the remainder consists of the hemispherical body, encased with polished wing-covers. The little black legs, while quite efficient because they can be moved so rapidly, are not the ladybird’s only means of locomotion; she is a good flier and has a long pair of dark wings which she folds crosswise under her wing-covers. It is comical to see her pull up her wings, as a lady tucks up a long petticoat; and sometimes ladybird is rather slovenly about it and runs around with the tips of her wings hanging out behind, quite untidily.

But any untidiness must be inadvertent, because the ladybird takes very good care of herself and spends much time in “washing up.” She begins with her front legs, cleaning them with her mandibles, industriously nibbling off every grain of dust; she then cleans her middle and hind legs by rubbing the two on the same side, back and forth against each other, each acting as a whisk broom for the other; she cleans her wings by brushing them between the edges of the wing-cover above and the tarsus of her hind leg below.

The ladybird is a clever little creature, even if it does look like a pill, and if you disturb it, it will fold up its legs and drop as if dead, playing possum in a most deceptive manner. It will remain in this attitude of rigid death for at least a minute or two and then will begin to claw the air with all its six legs in an effort to turn right side up.

From our standpoint the ladybird is of great value, for during the larval as well as adult stages, all species except one, feed upon those insects which we are glad to be rid of. They are especially fond of aphids and scale insects. One of the greatest achievements of economic entomology was the introduction on the Pacific Coast of the ladybird from Australia, called the Vedalia, which preys upon the cottony cushion scale insect, a species very dangerous to orange and lemon trees. Within a few years the introduced ladybirds had completely exterminated this pest.

The ladybird’s history is as follows: The mother beetle, in the spring, lays her eggs here and there on plants: as soon as the larva hatches, it starts out to hunt for aphids and other insects. It is safe to say that no ladybird would recognize her own children in time to save them, even if the house were burning, for they do not in the least resemble her; they are neither roly-poly nor shiny, but are long and segmented and velvety, with six queer, short legs that look and act as if they were whittled out of wood; they seem only efficient for clinging around a stem. The larvæ are usually black, spotted with orange or yellow; there are six warts on each segment, which make the creature’s back look quite rough. The absorbing business of the larva is to crawl around on plants and chew up the foolish aphids or the scale insects. I have seen one use its front foot to push an aphid, which it was eating, closer to its jaws; but when one green leg of its victim still clung to its head, it did not try to rub it off as its mother would have done, but twisted its head over this way and that, wiping off the fragment on a plant stem and then gobbling it up.

After the larva has shed its skeleton skin several times, and destroyed many times its own bulk of insects, it hunts for some quiet corner, hangs itself up by the tail and condenses itself into a sub-globular form; it sheds its spiny skin pushing it up around the point of attachment, and there lets it stay like the lion’s skin of Hercules. As a pupa, it is more nearly rectangular than round, and if we look closely, we can see the wing-cases, the spotted segments of the abdomen, and the eyes, all encased in the pupa skin; the latter bursts open after a few days and the shining, little half-globe emerges a full-grown ladybird, ready for hiding in some cozy spot to pass the winter, from which she will emerge in the spring, to stock our trees and vines, next year, with her busy little progeny.

_References_--American Insects, Kellogg; Manual for the Study of Insects, Comstock.

LESSON XCIII

THE LADYBIRD

_Leading thought_--The ladybird is a beetle. Its young are very different from the adult in appearance, and feed upon plant-lice.

_Method_--These little beetles are very common in autumn and may be brought to the schoolroom and passed around in vials for the children to observe. Their larvæ may be found on almost any plant infested with plant-lice. Plant and all may be brought into the schoolroom and the actions of the larvæ noted by the pupils during recess.

_Observations_--1. How large is the ladybird? What is its shape? Would two of them make a little globe if they were put flat sides together?

2. What colors do you find on your ladybird?

3. Do you see the ladybird’s head and antennæ? What is the broad shield directly back of the head called? How is it marked, and with what colors? What color are the wing-covers? Are there any spots upon them? How many? Does the ladybird use its wing-covers when it flies? Describe her true wings. Does she fold them beneath the wing-covers?

4. Note the legs and feet. Are the legs long? Are they fitted for running? To which part of the body are they attached?

5. If you disturb the ladybird how does she “play possum?” Describe how she makes her toilet.

_The larva_--1. Describe the ladybird larva. Does it look like its mother? What is its form? Is it warty and velvety or shiny?

2. Describe its head and jaws as far as you can see. How does it act when eating? Can you see its little stiff legs? Is there a claw at the end of each?

3. Describe the actions of the ladybird larva in attacking and eating the plant-lice. Does it shed its skin as it grows?

4. Watch a larva until it changes to a pupa. How does the pupa look? Can you see the shed skin? Where is it? To what is the pupa attached? When the pupa skin breaks open what comes out of it?

5. Why is the ladybird of great use to us? Write an English theme upon the ladybird, called Vedalia, which saved the orange orchards of California.

_The small beetle represents actual size._]

THE FIREFLY

_Teacher’s Story_

_And lavishly to left and right,
The fireflies, like golden seeds,
Are sown upon the night._
--RILEY.

The time of this sowing is during warm, damp nights in July and August, and even in September, although they are sown less lavishly then. How little most of us know of the harvest, although we see the sowing which begins in the early twilight against the background of tree shadows, and lasts until the cold atmosphere of the later night dampens the firefly ardor! There is a difference in species as to the height from the ground of their flight; some species hover next to the grass, others fly above our heads, but rarely as high as the tree tops in northern latitudes. Some species give a short flash that might be called a refulgent blinking; others give a longer flash so that we get an idea of the direction of their flight; and there is a common species in the Gulf States which gives such long flashes that they mark the night with gleaming curlicues.

It is likely to be an exciting chase, before we are able to capture a few of these insects for closer inspection; but when once captured, they do not sulk but will keep on with their flashing and give us a most edifying display. The portion of the firefly which gives the light is in the abdomen, and it glows steadily like “phosphorescent wood”; then suddenly it gleams with a green light that is strong enough to reveal all its surroundings; and it is so evidently an act of will on the part of the beetle, that it is startling to members of our race, who cannot even blush or turn pale voluntarily. The fireflies may be truly said to be socially brilliant, for the flashing of their lights is for the attraction of their mates.

The fireflies are beetles, and there are many species which are luminous. A common one is here figured (_Photinus pyralis_). It is pale gray above and the head is completely hidden by the big shield of the thorax. The legs are short; thus this beetle trusts mostly to its wings as a means of locomotion. The antennæ are rather long and are kept in constant motion, evidently conveying intelligence of surroundings to the insect. Beneath the gray elytra, or wing-covers, is a pair of large, dark-veined membranous wings which are folded in a very neat manner crosswise and lengthwise, when not in use. When in use, the wing-covers are lifted stiffly and the flying is done wholly with the membranous wings. Looked at from beneath, we can at once see that some of the segments of the abdomen are partly or entirely sulphur yellow, and we recognize them as the lamp. If the specimen is a male, the yellow area covers all of the end of the abdomen up to the fourth or fifth segment; but if it is a female, only the middle portion of the abdomen, especially the fifth segment, is converted into a lamp. These yellow areas, when dissected under the microscope, prove to be filled with fine tracheæ, or air-tubes; and although we know very little about the way the light is made, it is believed that by flooding the tubes with air, the oxygen in some way produces the light.

In some species, the female is wingless and has very short wing-covers, and a portion of her body emits a steady, greenish light which tells her lord and master where to find her. These wingless females are called glow-worms.

After C. V. Riley.]

Fireflies during their larval stages are popularly called wire worms, although there are many other beetle larvæ thus called. In many of the species, the firefly eggs, larvæ and pupæ are all luminescent, but not so brilliant as when adults. The larva of the species here figured, was studied by C. V. Riley, who gave us an interesting account of its habits. It lives in the ground and feeds on soft-bodied insects, probably earth-worms. Each segment of this wire worm has a horny, brown plate above, with a straight white line running through the middle and a slightly curved white line on each side; the sides of the larva are soft and rose-colored; the white spiracles show against little, oval, brown patches. Beneath, the larva is cream color with two brown comma-like dots at the center of each segment. The head can be pulled back completely beneath the first segment. The most interesting thing about this larva is the prop-leg at the end of its body, which naturally aids it in locomotion; but this prop-leg also functions as a brush; after the larva has become soiled with too eager delving into the tissues of some earthworm, it curls its body over, and with this fan-shaped hind foot scrubs its head and face very clean. This is a rare instance of a larva paying any attention to its toilet.

When full-grown, the larva makes a little oval cell within the earth and changes to a pupa; after about ten days, the pupa skin is shed and the full-fledged beetle comes forth. The larva and pupa of this species give off light, but are not so brilliant as the adult. The pupils should be encouraged to study the early stages of the fireflies, because very little is known concerning them.

In Cuba a large beetle called the cucujo has two great oval spots on its thorax, resembling eyes, which give off light. The Cuban ladies wear cucujos at the opera, in nets, in the hair. I once had a pair which I tethered with gold chains to the bodice of my ball gown. The eye-spots glowed steadily, but with the movement of dancing, they grew more brilliant until no glittering diamonds could compete with their glow.

LESSON XCIV

THE FIREFLY

_Leading thought_--When the firefly wishes to make a light, it can produce one that, if we knew how to make, would greatly reduce the price of artificial light; for the light made by fireflies and other creatures, requires less energy than any other light known.

_Method_--After the outdoor observations have been made, collect some of these beetles in the evening with a sweep net; place them under a glass jar or tumbler, so that their light can be studied at close range. The next day give the observation lesson on the insects.

_Observations_--1. At what time of year do you see fireflies? Do they begin to lighten before it is dark? Do you see them high in the air or near the ground? Is the flash they give short, or long enough to make a streak of light? Do you see them on cold and windy nights or on warm, still, damp evenings? Make a note of the hour when you see the first one flash in an evening.

2. Catch a few fireflies in the night; put them under a glass jar. Can you see the light when they are not flashing? What color is it? When they make the flash can you see the outline of the “firefly lamp?” Watch closely and see if you think the flashing is a matter of will on the part of the firefly. Do you think the firefly is signaling to his mate when he flashes?

3. Study the firefly in daylight. Is it a fly or is it a beetle? What color is it above? When you look squarely down upon it, can you see its head and eyes?

4. Are the firefly’s legs long or short? When a beetle has short legs is it a sign that it usually walks, runs or flies?

5. Describe the antennæ. Are they in constant motion? What service do you think the firefly’s antennæ perform for it?

6. Lift one of the wing-covers carefully. What do you find beneath it? Does the beetle use its wing-covers to beat the air and help it during flight? How does the beetle hold its wing-covers when flying?

7. Turn the beetle on its back. Can you see the part of the body that flashes? What color is it?

8. Do you know the life history of the firefly? What is it like in its earlier stages? Where does it live? Does it have the power of making light when it is in the larval stage?

* * * * *

“_There, in warm August gloaming,
With quick silent brightenings,
From meadow-lands roaming,
The firefly twinkles
His fitful heat-lightnings._”
--LOWELL

Photo by M. V. Slingerland.]

THE WAYS OF THE ANT

_My child, behold the cheerful ant,
How hard she works, each day;
She works as hard as adamant
Which is very hard, they say._
--OLIVER HERFORD.

Very many performances on the part of the ant seem to us without reason; undoubtedly many of our performances seem likewise to her. But the more understandingly we study her and her ways, the more we are forced to the conclusion that she knows what she is about; I am sure that none of us can sit down by an ant-nest and watch its citizens come and go, without discovering things to make us marvel.

By far the greater number of species of ants find exit from their underground burrows, beneath stones in fields. They like the stone for more reasons than one; it becomes hot under the noon sun and remains warm during the night, thus giving them a cozy nursery in the evening for their young. Some species make mounds, and often several neighboring mounds belong to the same colony, and are connected by underground galleries. There are usually several openings into these mounds. In case of some of the western species which make galleries beneath the ground, there is but one opening to the nest and Dr. McCook says that this gate is closed at night; at every gate in any ants’ nest, there are likely to be sentinels stationed, to give warning of intruders.

As soon as a nest is disturbed, the scared little citizens run helter skelter to get out of the way; but if there are any larvæ or pupæ about, they are never too frightened to take them up and make off with them; but when too hard pressed, they will in most cases drop the precious burden, although I have several times seen an ant, when she dropped a pupa, stand guard over it and refuse to budge without it. The ant’s eggs are very small objects, being oblong and about the size of a pin point. The larvæ are translucent creatures, like rice grains with one end pointed. The pupæ are yellowish, covered with a parchment-like sac, and resemble grains of wheat. When we lift stones in a field, we usually find directly beneath, the young of a certain size.

There are often, in the same species of ants, two sizes; the large ones are called majors and the smaller minors; sometimes there is a smaller size yet, called minims. The smaller sizes are probably the result of lack of nutrition. But whatever their size, they all work together to bring food for the young and in caring for the nest. We often see an ant carrying a dead insect or some other object larger than herself. If she cannot lift it or shove it, she turns around, and going backwards, pulls it along. It is rarely that we see two carrying the same load, although we have observed this several times. In one or two cases, the two seemed not to be in perfect accord as to which path to take. If the ants find some large supply of food, many of them will form a procession to bring it into the nest bit by bit; such processions go back by making a little detour so as not to meet and interfere with those coming. During most of the year, an ant colony consists only of workers and laying queens, but in early summer the nest may be found swarming with winged forms which are the kings and queens. Some warm day these will issue from the nest and take their marriage flight, the only time in their lives when they use their wings; for ants, like seeds, seem to be provided with wings simply for the sake of scattering wide the species. It is a strange fact, that often on the same day swarms will issue from all the nests of one species in the whole region; by what mysterious messenger, word is sent that brings about this unanimous exodus, is still a mystery to us. This seems to be a provision for cross-breeding; and as bearing upon this, Miss Fielde discovered that an alien king is not only made welcome in a nest, but is sometimes seized by workers and pulled into a nest; this is most significant, since no worker of any other colony of the same species, is permitted to live in any but its own nest.

Drawn by Evelyn Mitchell.]

After the marriage flight, the ants fall to the ground and undoubtedly a large number perish; however, just here our knowledge is lamentably lacking, and observations on the part of pupils as to what happens to these winged forms will be valuable. In the case of most species, we know that a queen finds refuge in some shelter and there lays eggs. Mr. Comstock once studied a queen of the big, black carpenter ant which lives under the bark of trees. This queen, without taking any food herself, was able to lay her eggs and rear her first brood to maturity; she regurgitated food for this first brood, and then they went out foraging for the colony. However, Miss Fielde found that in the species she studied, the queen could not do this; a question most interesting to solve is whether any of the young queens, after the marriage flight, are adopted into other colonies of the same species. As soon as a queen begins laying eggs, she sheds her then useless wings, laying them aside as a bride does her veil.

When we are looking for ants’ nests beneath stones, we often stumble upon a colony consisting of citizens differing in color. One has the head and thorax rust-red with the abdomen and legs brown; associated with this brown ant, is a black or ash-colored species. These black ants are the slaves of the brown species; but slavery in the ant world has its ameliorations. When the slave makers attack the slave nest, they do not fight the inmates unless they are obliged to. They simply loot the nest of the larvæ or pupæ, which they carry off to their own nests; and there they are fed and reared, as carefully as are their own young. The slaves seem to be perfectly contented, and conduct the household affairs of their masters with apparent cheerfulness. They do all the taking care of the nest and feeding the young, but they are never permitted to go out with war parties; thus they never fight, unless their colony is attacked by marauders.