An Elementary Study of Insects Part 2

How does a turkey catch them? Have you ever seen a dull colored fly, which inhabits dry paths and which flies with a humming sound like a bee, feeding on gra.s.shoppers? These are called "robber-flies" or "spider-hawks" and they destroy thousands of gra.s.shoppers.

BREEDING CAGE OBSERVATIONS

After you have learned all you can about the habits of the gra.s.shopper in the field, catch a few of them and take them home and put them in a gla.s.s fruit jar. Collect green leaves for them and watch them feed.

Watch their method of feeding closely and see how it differs from that of a horse or a cow. How do they move about in the jar? Which legs are used in walking? What do they do with the jumping legs while walking? Do they use their wings at all while in the jar? Watch them wash their face and feet after feeding. Give them leaves of different plants, especially of field and garden crops and determine which they like best. Can you find any plant which they will not eat? Find out how fast they feed and considering the life of any one individual to be 200 days, calculate the number of gra.s.s blades each individual may eat. Are the feelers used while in the jar, and if so for what purpose?

STUDY OF SPECIMEN

Take a gra.s.shopper from the jar and examine it carefully. Count the number of legs, wings and joints in the body. How many joints in the legs? Examine the tip of the foot for a soft pad and on either side of it a strong hook. What are these used for? What are the sharp spines on the side of the hind-legs for? Examine the side of the body and see if you can find the small breathing pores. How do the legs join the body?

Where are the wings attached? How broad are the wings as compared with the body? How are they folded? Are the two pairs of wings alike? Which is used most in flying? Is the head firmly attached to the body? Examine the large eyes; where are they found? Will gra.s.shoppers bite you while handling them? What is the brown juice which escapes from the mouth when disturbed? How long are the feelers as compared with the body? Can you tell the males from the females? What is the distinction? Do they ever make music? Examine for all the foregoing points and write a brief report covering these. Make a careful drawing of a gra.s.shopper from one side; also make an enlarged drawing of the face of a gra.s.shopper and name the parts.

CHAPTER IV

THE HOUSE FLY OR TYPHOID FLY

In the house fly we find one of man's most deadly foes. War can not compare with the campaigns of disease and death waged by this most filthy of all insects. In our recent strife with Spain we lost a few lives in battle, but we lost many more in hospitals due to contagious diseases, in the transmission of which this pest played a most important part.

The fly is dangerous on account of its filthy habits. It breeds in filth, feeds on filth in open closets, slop-barrels, on the streets and in back alleys and then comes into the house and wipes this germ-laden filth on our food or on the hands or even in the mouths of helpless babies. Who has not seen flies feeding on running sores on animals, or on "spit" on sidewalks? These same flies the next minute may be feeding on fruits or other food materials. We rebel when pests destroy our crops or attack our stock, but here we have a pest which endangers our very lives, and the lives of those dear to us.

If the fly confined itself to filth we could overlook it as it would help to hasten the removal of filth. On the other hand, if it avoided filth and remained in our home we could not overlook it, but we could feel safe that it was not apt to do us a great deal of harm. But, like the English sparrow, one minute it is here and the next somewhere else; from filth to foods and then back again to filth. In this way it carries disease germs upon its feet and other parts of its body and by coming in contact with food material some of these germs are sure to be left on it and cause trouble later. The fly's method of carrying disease is different from that of the mosquito where the germ is carried inside its body.

[Ill.u.s.tration: House fly; a, larva or maggot; b, pupa; c, adult; e, egg.

All enlarged. (Modified from Howard Bur. of Entomology. U. S. Dept.

Agri.)]

The presence of flies in the home is usually a sign of untidiness; but it means more, it means that disease and often death is hovering over the home. We are too apt to consider the fly simply as a nuisance when we should take it more seriously. The child should be led to realize that the fly should not be tolerated in the home, that it is dangerous and that it can and must be destroyed.

The house fly may pa.s.s the winter either as the adult fly in cracks and crannies about the home, or in out-buildings or it may remain as a hard, brown, oval pupa in stables and manure piles when, with the first warm days of spring, it escape from this case as the fly ready to lay eggs for the first colony. The fly breeds largely in horse manure either in stables, manure piles or in street gutters where manure is allowed to collect. Each female lays a large number of eggs and since it requires less than two weeks for the pest to mature, we are soon overrun with flies in the summer where steps are not taken to control them. The maggots are often so abundant in stables that they can be scooped out with a shovel. This ceaseless breeding continues from spring until the first frost in the fall.

[Ill.u.s.tration: Favorite breeding places of house fly. Such places should be kept as clean and neat as the front yard.]

In the control of the fly and prevention of trouble from it there are three important steps to take. First of all, go to the source of the trouble and do away with or screen all breeding places. Then, by keeping in mind the fact that the fly is comparatively harmless as long as it is kept from filth laden with germs, do away with all open closets, uncovered slop-barrels and other filth. As a further precaution keep it from the home by the use of screens and when necessary "swatters." Do not make the mistake of trying to control the pest with the "swatters"

alone. In the country too often manure is permitted to acc.u.mulate about the barn during the summer with a view of using it on wheat ground in the fall and this furnishes ideal conditions for the fly to breed.

Another source of constant danger especially in the rural districts is the presence of open closets or worse still the presence of no closet at all. This is without doubt the most dangerous accessory of the farm.

More screens should be used in the home and greater care in keeping them closed.

[Ill.u.s.tration: An open closet to which the house fly has free access.

Such a closet is the most dangerous accessory of any home.]

STUDY OF THE FLY AND ITS WORK

Observe first of all the feeding habits of the fly. What foods in the home is it most fond of? Make a list of all the food materials it is found to feed on. Where and on what is it found feeding out doors? Do you find it feeding on filth and if so, on what? Do you find it about the barn? Where is it usually found in the barn? How can the fly carry filth to food materials?

In studying the breeding of the fly determine where it lays its eggs and where the maggots are found. Examine fresh manure in the stable and see if you can find small white maggots about half an inch long and as large around as the lead in a pencil. If you do, place some of them with some fresh manure in a gla.s.s jar and see what becomes of them. In a few days the maggots will disappear and in their places small oval, brown bean-like objects will appear. A few days later these will crack open at one end and the fly will crawl out. Keep records of the length of time it requires for the pest to pa.s.s from one stage to the other. If maggots cannot be gotten put some fresh manure in the jar and catch a number of live house flies and put them in with the manure and watch for results.

Collect a jar of fresh manure with maggots and sift over it a little powdered borax and see what happens to the maggots. Where horse manure can not be properly disposed of, cheap borax is used to throw over piles of manure to destroy the maggots and prevent the flies from breeding in it. Write a brief description of the different stages and make careful drawings of these. Do not mistake the house fly for other flies often found on food in the home.

Collect a few flies and put them in a bottle and drop in with them just a few crumbs of sugar and watch them feed. They cannot chew but a little saliva from the mouth dissolves a little of the sugar which is then lapped up as syrup. Notice what a peculiar sucker they have for drawing up liquids. How can they crawl along in the bottle with their backs toward the floor? Examine the tip of their feet for a small glue pad which sticks to the gla.s.s. These glue pads and the sucker are well fitted for carrying filth. Examine the fly carefully and write a brief description of it. What color is it? How many legs? How many wings? Are these transparent? Behind the wings there is a pair of small stubs which is all that is left of the hind pair of wings. Are the eyes large? Can you find a pair of small feelers? Why can you not pick up a fly like you would a gra.s.shopper? Is their eye sight good? Why are they always most abundant on a kitchen screen door? Can they smell?

What are the fly's worst enemies? Will the toad eat them? Do chickens eat them? Have you ever seen chickens scratching in manure and feeding on the fly maggots? Put a few drops of formaldehyde, which you can get from a druggist, in a few spoonfuls of sweet milk or sugar syrup and let the flies eat it and see what happens to them. This is one of our best poison baits for flies which get in the home or collect about the dairy.

Formaldehyde is a poison and when used in bait it must be kept out of reach of children. Just about frost, in the fall, watch for the appearance of inactive flies on walls, windows and other parts of the house. These have been attacked by a parasitic disease. These are often found sticking to walls and other objects about the room in the winter, and are commonly thought to be pa.s.sing the winter.

"_The insect we now call the 'house fly' should in the future be termed the 'typhoid fly,' in order to call direct attention to the danger of allowing it to continue to breed unchecked._"

--L. O. HOWARD.

CHAPTER V

THE MOSQUITO

Here we have another small insect which, like the house fly, is extremely dangerous, due to its ability to carry the germs of disease.

There are hundreds of species of mosquitoes, some small, some large. The majority of these are unable to carry disease so far as we know at present, but they should be avoided as dangerous. The Missouri forms which carry disease are the so-called malarial fever mosquitoes, and they are entirely responsible for the transmission of this sapping and often fatal disease. In the warm countries these are more abundant and the fever is more fatal. In the south there is still another disease-carrying mosquito, the yellow fever mosquito. This form is most dangerous of all.

The mosquito first bites a patient suffering with malaria and in this way it takes in germs along with the blood which it sucks from the patient. After these germs pa.s.s through stages of development in the body of the mosquito they are ready to be injected back into a healthy person where, in due time, they cause the disease. The germs feed inside the red blood corpuscles and at regular intervals they destroy a large number of these causing a chill which is followed by fever and a new supply of corpuscles is produced. This alternation of chill and fever may continue all summer, if medicine is not taken to destroy the germs.

Quinine will kill the germs if it is taken so that plenty of it is in the blood when the germs come out of the torn down corpuscles during a chill.

In order to prevent malarial fever, get rid of the mosquitoes by draining and oiling the breeding places, escape their bites by screening houses, smudging and destroying the adults, and keep the mosquitoes from patients who have the fever. This is almost as important as the destruction of the mosquitoes. The malarial fever mosquitoes are as harmless as our common forms so long as they do not become infected with germs by sucking blood from a fever patient.

[Ill.u.s.tration: Mosquitoes in position for biting; a, common Culex mosquito; b, malarial fever mosquito. Note that the one stands parallel, while the other stands at an angle to the surface on which it rests.]

In view of the fact that most of our common mosquitoes are cla.s.sed as non-dangerous, it is of interest to know just how to distinguish the harmless ones from the dangerous. The adults of the two forms can be easily distinguished when they are seen at rest. The common forms always rest with the body parallel to the surface on which they rest, while the malarial form always elevates the end of the body so that the head is pointed toward the surface on which it rests. In like manner the wigglers can be distinguished from each other. Our common wigglers always hang head downward in the water while those of the malarial mosquitoes rest near the surface of the water with their bodies parallel to it. The majority of the wigglers found in rain barrels are of our common forms.

[Ill.u.s.tration: Common Culex mosquito showing stages of development; a, raft of eggs; b, larvae or wigglers of different sizes; c, pupa; d, mosquito. The large wiggler and the pupa are taking air from the surface of the water through their breathing tubes.]

The life of the mosquito is quite interesting and is an excellent example of an insect which lives in the water part of its life and in the air the rest. The mature female mosquito, which does all the biting, searches for water in rain barrels, cans, ditches, ponds, and stagnant swamps where she lays her eggs either in raft-shaped packets or singly. When the wigglers hatch they swim about in the water and feed upon decaying material and microscopic water plants. When the wiggler is full grown it changes to an active pupa which has a large head and a slender tail and is more or less coiled. A little later the winged mosquito escapes. In the rural districts most of the mosquitoes breed in stagnant ponds, swamps and rain barrels and from these they fly to the home where they cause trouble. Such places should be drained or protected with oil or other means to prevent the mosquito from using them for breeding purposes. Ponds can be freed of the wigglers by introducing fish or by using a small amount of coal oil on the surface.

The wigglers have a breathing tube which is thrust out above the water when fresh air is needed and if there is a thin film of oil on the water this is prevented. Rain barrels can be freed of the pest in this way also, or perhaps better by covering them with a cloth. The mosquitoes are most troublesome about the home at night. When one sits out doors he should keep a smudge going to drive them away while screens will keep them out of the house at night.

OBSERVATIONS AND STUDY

Collect all the different kinds of mosquitoes you can find and note difference in size and markings. Do you find the malarial fever mosquito in your region? Is malarial fever common during the summer and fall? Are there any old stagnant ponds or swamps near your home? If so, examine these for wigglers. Examine rain barrels for small raft-shaped packets of eggs. These resemble small flakes of soot and are difficult to pick up between your fingers. Take a stick and lift them from the water and examine them. One packet may contain a hundred or more eggs. Put a few of these packets in a tumbler of rain water and watch for the wigglers.

At first they will be very small but they grow fast. Watch them come to the surface to breathe. The tip of the tail is projected above the water and air is taken in at two small breathing pores or spiracles. Examine rain barrels for the larger wigglers. What do they live on in the rain barrel? What do they do when you jar the barrel? Do you find any of the rounded pupae in the barrel? They are active the same as the wigglers.

If you find pupae, put some in a tumbler of water, cover it with cloth or a lid and watch for the mosquitoes to appear. After collecting several mosquitoes examine them for number of wings, legs and markings and see if all have the slender sucking tube. The males have large feathery feelers, but no sucking tube.

Write a brief description of the wiggler and the mosquito, their breeding places and means of destroying them. Make drawings of the different stages, wiggler, pupa and mosquito.