ear-by tree in order to deposit her eggs upon the twigs. These
eggs (shown at _a_ and _b_) hatch into the greedy larvae that do so much
damage to our orchards.

Nearly all the common birds feed freely upon the cankerworm, and benefit
the orchard in so doing. The chickadee is perhaps the most useful. A
recent writer is very positive that each chickadee will devour on an
average thirty female cankerworm moths a day; and that if the average
number of eggs laid by each female is one hundred and eighty-five, one
chickadee would thus destroy in one day five thousand five hundred and
fifty eggs, and, in the twenty-five days in which the cankerworm moths
crawl up the tree, would rid the orchard of one hundred and thirty-eight
thousand seven hundred and fifty. These birds also eat immense numbers
of cankerworm eggs before they hatch into worms.

[Illustration: FIG. 158. EGGS OF THE FALL CANKERWORM]

_Treatment._ The inability of the female to fly gives us an easy way to
prevent the larval offspring from getting to the foliage of our trees,
for we know that the only highway open to her or her larvae leads up the
trunk. We must obstruct this highway so that no crawling creature may
pass. This is readily done by smoothing the bark and fitting close to it
a band of paper, and making sure that it is tight enough to prevent
anything from crawling underneath. Then smear over the paper something
so sticky that any moth or larva that attempts to pass will be
entangled. Printer's ink will do very well, or you can buy either
dendrolene or tanglefoot.

[Illustration: FIG. 159. APPLE-TREE TENT CATERPILLAR
_a_, eggs; _b_, cocoon; _c_, caterpillar]

Encourage the chickadee and all other birds, except the English sparrow,
to stay in your orchard. This is easily done by feeding and protecting
them in their times of need.

=The Apple-Tree Tent Caterpillar.= The apple-tree tent caterpillar is a
larva so well known that you only need to be told how to guard against
it. The mother of this caterpillar is a reddish moth. This insect passes
the winter in the egg state securely fastened on the twigs as shown in
Fig. 159, _a_.

_Treatment._ There are three principal methods, (1) Destroy the eggs.
The egg masses are readily seen in winter and may easily be collected
and burned by boys. The chickadee eats great quantities of these eggs.
(2) With torches burn the nests at dusk when all the worms are within.
You must be very careful in burning or you