e distended with eggs. (After
Karsten.)]

[Illustration: FIG. 35--Bedbug (_Cimex lectularis_).]

[Illustration: FIG. 36--Body-louse (_Pediculus vestimenti_). (From
drawing by J.H. Paine.)]

HOW INSECTS MAY CARRY DISEASE GERMS

Insects may carry the germs or parasites which cause disease in a purely
mechanical or accidental way, that is, the insect may in the course of
its wanderings or its feeding get some of the germs on or in its body
and may by chance carry these to the food, or water, or directly to some
person who may become infected. Thus the house-fly may carry the typhoid
germs on its feet or in its body and distribute them in places where
they may enter the human body.

Several other flies as well as fleas, bedbugs, ticks, etc., may also
carry disease germs in this mechanical way. While this method of
transmission is just as dangerous as any other, and possibly more
dangerous because more common, another method in which the insect is
much more intimately concerned is more interesting from a biological
standpoint at least and will be discussed more fully in the chapters on
malaria, yellow fever and elephantiasis.

In these cases the insect is one of the necessary hosts of the parasite,
which cannot go on with its development or pass from one patient to
another unless it first enters the insect at a certain stage of its
life-history.

[Illustration: FIG. 37--One use for the house-fly.]

BABY-BYE.

1. Baby-Bye,
Here's a fly;
We will watch him, you and I.
How he crawls
Up the walls,
Yet he never falls!
I believe with six such legs
You and I could walk on eggs.
There he goes
On his toes,
Tickling Baby's nose.

CHAPTER V

HOUSE-FLIES OR TYPHOID-FLIES

The page shown in Fig. 37 was copied from one of our old second readers
and shows something of the spirit in which we used to regard the
house-fly. A few of them were nice things to have around to make things
seem "homelike." Of course they sometimes became too friendly during the
early morning hours when we were trying to take just one more little nap
or they were sometimes too insistent for their portion of the dinner
after it had been placed on the table, but a screen over the bed would
help us out a little in the morning and a long fly-brush cut from a tree
in the yard or made of strips of paper tacked to a stick or, still more
fancy, made of long peacock plumes, would help to drive them from the
ta