SHADE TREE INSECTS 
- . +. LESSON NUMBER TEN - - - 
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PART I. 30 4! 
BORERS Dwg 
NOTE TO STUDENTS: It is important that the 
Tree Surgeon should not only know when a tree needs his 
technical skill in removing decay and repairing injuries, 
but he should also be able to quickly detect the presence of 
any agency liable to injure or kill the tree. 
In the last lesson you studied the fungous and similar 
diseases tending to injure or kill shade trees, but the in- 
sects, one of the commonest causes of disease as there de- 
fined, were considered of too great importance to be 
treated at that time. 
The present lesson is the introduction to this very im- 
JOHN DAVEY portant subject, and will consider the borers, or those in- 
“FATHER OF sects which burrow under the bark or into the harder parts 
TREE SURCERY” Of the trees. Their habit of working entirely within the tree 
makes them very hard to control, and they frequently 
cause serious injury before even their presence is suspected within the tree. 
The control of the borers is such a difficult problem that few entomo- 
logists have given it the attention that it deserves; consequently, the litera- 
ture on the subject is widely scattered, and much of it is very unreliable. For 
this reason a full lesson will be devoted to this important subject, and the 
other shade tree insects will be left for the next lesson. The fruit insects 
will be considered under the subject of fruit growing. 
The science of economic entomology, to which you are introduced in this 
lesson, is so vast and so important that most of your information must come 
from your text books and from the references furnished you. All that can be 
done in the lessons is to consider a few of the more important and representa- 
tive species, and those with which you are most liable to have to deal in your 
future work as Tree Surgeons. By having a thorough understanding of these, 
you will also be able to deal successfully with the other related species when 
you meet them. 
Copyright, 1914. The Davey Institute of Tree Surgery, Kent, Ohio. 
