hould be
examined three or four times a year for wilted twigs, dead branches,
and strings of expelled frass; all of which may indicate the
presence of this borer. Badly infested branches should be cut off
and burned. Trees so badly infested that treatment becomes too
complicated should be cut down and destroyed. Where the insects are
few and can be readily reached, an injection of carbon bisulphide
into the burrow, the orifice of which is then immediately closed
with soap or putty, will often destroy the insects within.

[Illustration: FIG. 107.--Elm Tree Attacked by the Leopard Moth.]

THE HICKORY BARK BORER

Life history: This insect is a small brown or black beetle in its mature
form and a small legless white grub in its winter stage. The beetles
appear from June to August. In July they deposit their eggs in the
outer sapwood, immediately under the bark of the trunk and larger
branches. The eggs soon hatch and the grubs feed on the living
tissue of the tree, forming numerous galleries. The grubs pass the
winter in a nearly full-grown condition, transform to pupae in May,
and emerge as beetles in June.

Remedies: The presence of the insect can be detected by the small holes
in the bark of the trees and the fine sawdust which is ejected from
these holes, when the insects are active. It is important to
emphasize the advisability of detecting the fine sawdust because
that is the best indication of the actual operations of the hickory
bark borer. These holes, however, will not be noticeable until the
insect has completed its transformation. In summer, the infested
trees show wilted leaves and many dead twigs. Holes in the base of
the petioles of these leaves are also signs of the working of the
insect. Since the insect works underneath the bark, it is
inaccessible for treatment and all infested trees should be cut down
and burned, or the bark removed and the insects destroyed. This
should be done before the beetles emerge from the tree in June.

PLANT LICE OR APHIDES

These often appear on the under side of the leaves of the beech, Norway
maple, tulip tree, etc. They excrete a sweet, sticky liquid called
"honey-dew," and cause the leaves to curl or drop. Spraying with
whale-oil soap solution formed by adding one pound of the soap to five
gallons of water is the remedy.

STUDY II. TREE DISEASES

Bec