24 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
BORERS IN LIVING TREES 
The control of borers in living trees is well known to be a difficult 
matter. Many species of borers rattack only weakened or dying trees, 
and after the attack the larvae are well protected by a thick layer of 
impervious bark. In the forest, it is impractical to attempt control 
except through the sacrifice of the infested tree; and often in shade 
and ornamental tr ees, the condition is discovered too late to apply a 
remedy. 
There are two distinct types of borers causing damage to living 
trees. The first attacks sparingly over the stem, boring individual 
galleries under the bark and into the wood of apparently healthy 
trees. This group includes the species of Goes and Romalewm, and 
some species of Saperda, the carpenter worm, pitch moths, the maple 
borer, locust borer, and others. In the early stages, while the borers 
are in or under the bark, their work causes an exudation of sap and 
boring dust. Later, large excavations are extended into the wood. 
These holes weaken small trees, and often result in the breaking off 
of the affected part, and in larger trees they serve as points of entrance 
for decay. 
In valuable trees the simplest method of treatment is to drop a small 
quantity of some fumigant into the borer tunnel. Carbon disulfide 
or carbon tetrachloride are recommended. The holes should then be 
plugged with moist soil or putty. Where the borers are numerous. 
painting or spraying with orthodichlorobenzene emulsions or with 1 
pound of paradichlorobenzene dissolved in 2 quarts of cottonseed oil 
is often effective. For formulas and details of application, see pp. 
25-26. 
The second class of borers, those that attack in great numbers over 
a considerable portion of the tree and extend the larval mines under 
the bark of the larger branches or the entire trunk, are represented 
by such genera as Agrilus, Melanophila, Tylonotus, Chrysobothris, and 
by some species of Saperda. These borers are dependent on a lowered 
vitality of the tree for successful attack. There is really no effective 
means of controlling them after the borers are well established in the 
tree. As they bore beneath the bark and have no exit holes to the 
outside, it is impossible to reach them with sprays. Usually by the 
time the tree is attacked throughout, it is too late to apply effective 
measures, 
Recent work with DDT indicates that it may be effective in prevent- 
ing attack of many borers if the trees are sprayed at the time the adults 
are active. A concentration of 2 to 5 percent, apphed either as an 
emulsion or a wettable powder, is effective. 
DDT is poisonous and should be handled with care. It should 
be stored in clearly labeled packages and kept away from food 
products. The use of DDT on ornamental plants growing close 
to fish ponds or streams should be avoided, since there is danger 
of killing fish and other aquatic life. DDT in oil solutions and 
emulsions may be absorbed through the skin of man and animals. 
Persons using it in these forms should take special precautions 
to avoid repeated or prolonged exposures to the material. 
