extreme
sensitiveness of insects to touch. The brain is comparatively small
except in the bees and ants. The circulatory system consists simply of a
long tube heart, the blood vessels being absent. In this way the
internal organs of the insect are simply bathed in the blood. The
system of respiration is most complicated. The air is taken in through
pores usually along the side of the body and is then carried through
fine tracheal tubes to all parts of the body. You cannot drown an insect
by putting its head under water, since it does not breathe through its
mouth. The muscular system is similar to that of other animals which
have the skeleton on the outside.

[Illustration: The internal organs of the honey bee. Note the strong
wing muscles in the thorax. The tube-like heart begins in the head and
extends back through the thorax and follows the curve of the abdomen.
Below the heart is the digestive tube consisting of the slender
oesophagus which extends back to the expanded honey stomach, in which
the bee carries the nectar it collects from flowers, then the curled
true stomach, the small intestine and expanded large intestine. Below
this is the nervous system consisting of the brain and a chain of
connected enlargements or ganglia extending back into the abdomen in the
lower part of the body. The respiratory system in part appears just
above the honey stomach, and the black circular or oval spots are cross
sections of connecting air tubes, which run all through the body. Also
note the sting with the poison gland and sack which are pulled out with
the sting; also the sucking tube for getting honey from flowers, and the
structures on the legs for gathering and carrying pollen; the pollen
basket is on the back side of the hind leg.]

_Their Methods of Developing_

In most cases the parent insect deposits small eggs which hatch later
into the young insects. In some cases, as with the blow-flies, the
maggot may hatch from the egg while yet in the parent's body, when the
active larva is born alive. Whether the egg hatches before or after it
is deposited, the young insect continues to develop in one of three
ways. It may resemble the parent and simply grow as does a kitten, or it
may look somewhat like its parent though smaller and without wings, as
the young grasshopper, or it may bear no resemblance whatever to the
parent, as the caterpillar which feeds and grows and finally spins a
cocoon in which it passes to the rest