ps much more than the birds themselves do.

As to their food, birds are divided into three general classes. First,
those that live wholly or almost wholly on insects. These are called
insectivorous birds. Chief among these are the warblers, cuckoos,
swallows, martins, flycatchers, nighthawks, whippoorwills, swifts, and
humming-birds. We cannot have too many of these birds. They should be
encouraged and protected. They should be supplied with shelter and
water.

Birds of the second class feed by preference on fruits, nuts, and grain.
The bluebird, robin, wood thrush, mocking-bird, catbird, chickadee,
cedar-bird, meadow lark, oriole, jay, crow, and woodpecker belong to
this group. These birds never fail to perform a service for us by
devouring many weed seeds.

[Illustration: FIG. 280. A KINGBIRD]

The third class is known as the hard-billed birds. It includes those
birds which live principally on seeds and grain--the canary, goldfinch,
sparrow, and some others.

Birds that come early, like the bluebird, robin, and redwing, are of
special service in destroying insects before the insects lay their eggs
for the season.

The robins on the lawn search out the caterpillars and cutworms. The
chipping sparrow and the wren in the shrubbery look out for all kinds of
insects. They watch over the orchard and feed freely on the enemies of
the apple and other fruit trees. The trunks of these trees are often
attacked by borers, which gnaw holes in the bark and wood, and often
cause the death of the trees. The woodpeckers hunt for these appetizing
borers and by means of their barbed tongues bring them from their
hiding-places. On the outside of the bark of the trunk and branches the
bark lice work. These are devoured by the nuthatches, creepers, and
chickadees.

During the winter the bark is the hiding-place for hibernating insects,
which, like plant lice, feed in summer on the leaves. Throughout the
winter a single chickadee will destroy great numbers of the eggs of the
cankerworm moth and of the plant louse. The blackbirds, meadow larks,
crows, quail, and sparrows are the great protectors of the meadow and
field crops. These birds feed on the army worms and cutworms that do so
much injury to the young shoots; they also destroy the chinch bug and
the grasshopper, both of which feed on cultivated plants.

[Illustration: FIG. 281. A WARBLER]

A count of all the different kinds of animals shows that insects make up
nine tenths