so closely that the tree is killed; for
the trees breathe through their leaves and can no more do without them
than they can without their roots.

The gypsy moth, which did no great harm in its European home, was
brought to this country and accidentally set free. It at once began to
attack the leaves of the elm, that beautiful tree of the old New England
villages. Now it is destroying other trees and, notwithstanding the
fight which we have made against it, we have not yet been able to
exterminate it.

[Illustration: _American Forestry Association_
Insects are destroying the trees of this forest.]

The chestnut tree, which every Eastern child loves for its nuts, is now
being destroyed by a fungus which may kill every one of these trees in
the country.

The white-pine blister, also brought over from Europe, is now
threatening all the white pines and the related trees of our country.
This disease has already such a start in the East that we may not be
able to stop it.

The dainty mistletoe, about which there are so many pretty Christmas
legends, is a deadly enemy of many trees. The seed of this fungus is
carried, by the birds or by the wind, from one tree to another. When it
sprouts, tiny roots go down through the bark to the sap, on which it
feeds until the tree is killed.

All our fruit trees have their deadly enemies which cause a loss of
many millions of dollars every year. Among the worst of these is the San
Jose scale, which was carelessly brought into the country from China.

[Illustration: _Pillsbury's Pictures, Inc._
A dwarf white pine which has found a foothold in the rocks on a
mountain top.]

The pear blight has destroyed whole orchards of pear trees in the
Western states. The citrus canker is now threatening the orange orchards
of the Southern states.

For years we have been searching over the world for new and better
varieties of fruit trees. With the shipments of such trees we have
brought some of the worst of the diseases that we have just mentioned.
We should have all foreign trees most carefully inspected before
admitting them to the country. We should also be very careful about
shipping fruit or other trees from one part of our country to another.
Diseases are often carried in this way into places which otherwise they
could not reach.

Field mice, gophers, and rabbits eat the bark of young fruit trees and
kill those which are not carefully protected. In some parts of our
country t