INTRODUCTION. 

 Scope . 



This Manual is for the use of Forest officers in 

 District 5. It does not apply, except in part, to infes- 

 tations outside of California. The data on which it is 

 based have been collected largely during insect reconnais- 

 sance and control work on Forests in this District, prin- 

 cipally on control projects on the Id am at h, Trinity, Cali- 

 fornia, Stanislaus and Sierra. It covers the v;ork of the 

 most important insects which cause the death of California 

 conifers, and presents a form of working plan for future 

 insect control operations. 



Only species of comercially important trees having 

 a more or less general distribution are considered in the 

 present control problem. Species which are of local distribu- 

 tion will be studied as the necessity arises. 



Suggestions or corrections from Forest officers, 

 familiar with the line of work, are invited. 



^urpose. 



The purpose of this Manual is to give Forest offi- 

 cers a general idea of the insect control problem, to pro- 

 vide information which will enable them to determine the 

 cause of, and the kind of infestation with which they may 

 have to deal, and also to furnish outlines for the various 

 reports anri investigations conducted in this District. 



