FIG. 79.--Photograph of the worm stage or larva of the
fly at the left and three of the sleeping stage or pupae at the right.
Twice the natural size.]

=How to fight the Flies.=--House flies lay at one time about one
hundred eggs in the dirt thrown out of horse stables, in garbage cans,
or in any other unclean place. In a day or two the eggs hatch into
little white worms which feed on the dirt. One or two weeks later the
worms change to flies.

Flies may be kept out of houses by putting screens in the windows and
doors or by darkening the rooms when they are not in use. The few
which gain entrance may be caught in fly traps. All food in the store
or the home should be kept covered. It is not safe to eat candy on
which flies have wiped their feet or to drink the milk in which they
have washed them.

[Illustration: FIG. 80.--Photograph of a half handful of manure which
had been thrown out of a horse stable. Note more than one hundred
houseflies in the sleeping stage.]

The surest way to get rid of flies in any community is for all the
people to work together and keep the entire neighborhood clean. No
dead grass, weeds, or rags should be allowed to lie in the backyards
or alleys. The cleanings from stables should be hauled away every
week or stored in tightly covered boxes. Garbage cans must have
close-fitting lids, so that there will be no place in which the young
may hatch and grow.

=Other Insects which carry Disease.=--In certain parts of Africa, the
_sleeping sickness_ has made ruins of prosperous villages. Thousands
of the natives are dying yearly from this disease. The germs are
carried from one person to another by the bite of a fly.

Some fleas carry the germs of _plague_, which a few centuries ago
swept across Asia and Europe destroying hundreds of lives daily. The
plague is now common in India and was present in California in 1908
and 1910. The bedbug spreads several kinds of fevers in warm countries
and may also be a carrier of leprosy and typhoid fever. These facts
show that insects are dangerous and should be kept out of the home.

Any one troubled with these little pests in the house may learn how to
get rid of them by writing to the Department of Agriculture,
Washington, D.C.

CHAPTER XVIII

HOW THE BODY MOVES

=The Need of a Framework.=--The body needs a stiff framework made of
bones for three purposes. One purpose is to give it shape, a second
purpose is to help the body move, and a