Evening star., 1937-10-02
VIGILANCE NEEDED
FOR TREE BORERS
Healthy Condition Defeats
One l'ype-0ther Permits
No Sure Cure.

Boring insects are about the most
care for trees have to contend. accord
Ing to Paul Davey. well-known expert,
in his adv ce to home owners on the
care of trees. He says they are not
so easy to find as chewing insects, be-
cause they bore in and get out of
sight. while the chewing insect stays
on the surface. He continues:
They are harder to find for another
reason. too. and that is that the dam
age they do is not so Immediately
observable AS that done by the chew
ing or sucking insects. Sometimes
before the damage done by borers is
discovered a tree has been mortally
injured. Even after the borers are
definitely located it is hard to kill
them without inf1icting worse injury
on the tree.
"A single borer usually does not
particularly hurt tree. But eggs are
laid which hatch many young and
these in turn develop and bore their
own tunnels. In their feeding borers
often cut across the channels which
convey the sap. A little grub working
around tree under the bark, as the
bronze birch borer grub works, will
girdle a tree as effectively as it would
be done with a knife or an AK and
with the same fatal effect to the tree
Two General Types.
There are various classifications Of
borers. but for control purposes they
may be divided into two general groups,
which may be described as primary
and secondary borers The primary
borers are those which will bore into
any tree of their preferred kind, no
matter what its condition may be,
while those which may be described as
secondary borers have a decided pref
erence for ailing or injured trees
The elm bark BEETLES, of which there
are several kinds, are good specimens
Of this secondary group. They prefer
to attack weak trees. If the tree at
tackled has malignant disease. such as
the dreaded Dutch elm disease, it is
one OF these beetles that is thought to
spread it.
while these secondary borers are
very dangerous because of the likeli-
hood OF their spreading disease. they
are also the easiest to guard against,
because if the health of a tree is
preserved. that tree is protected from
attack When a tree is so seriously
diseased that it has to be destroyed.
every piece of trunk. branch and bark,
down to the smallest chip. should be
burned. so that the borers which may
be in 1t will never get a chance to
mature.
Spraying Aids Protection.
For the primary borer no definite
general plan of control can be recon-
mended The fact that some of the
borers feed on leaves and twigs before
the egg-laving period suggests that
careful and continuous spraying will
dispose of many of the beetles. Good
authorities contend that trees which
are regularly given poison sprays are
never seriously infested with borers.
In localities where birch trees are i'm
portant. it may be remembered that
the bronze birch borer feeds on both
birch and elm foliage in the early
Summer months, so that poison sprays
at those times may do some good.
There are proprietary remedies for
subsurface applica ton on the market
When sawdust at the foot of a trunk
or on branch enable the borer hole
to he found. these remedies may be
forced into the holes and do Some
good, although they cannot be said
to be positive under all conditions.
About the only advice that can be
given is to be always on the alert for
borers and when they are found use
all known means to get as many as
you can"