54 PRACTICAL TREE REPAIR 



throughout the country is so very large that a com- 

 plete account of them would be more confusing 

 than helpful to the average reader. I shall there- 

 fore describe only the principal classes of insects 

 damaging the bark and wood of trees, illustrating 

 the habits of each class by a brief account of its 

 more important members. Suggestions for pre- 

 ventive measures will be correlated with the life 

 histories, the proper adaptation of operations to 

 the seasonal changes of the insect being all-impor- 

 tant in this kind of work. 



Almost all damage done by insects to the bark 

 and wood of trees is done by them while they are 

 in the larval or grub form. As is universally 

 known, insects assume two distinctly different 

 shapes during their lives. During the first part 

 of their existence they are highly specialized for 

 the consumption of food in large quantities and 

 for rapid growth. That growth completed, after 

 a longer or shorter period of dormant transforma- 

 tion (the pupal stage), they come forth in the 

 adult, usually winged, form, especially adapted to 

 reproduction and the wide distribution of the 

 species. It is the voracious grubs which damage 

 our trees. 



Broadly speaking, the insects we are at present 

 dealing with can be divided into two classes, ac- 

 cording to the part of the tree in which the larva 

 feeds and lives. There are bark borers and wood 



