VIII THE SCOLYTID BEETLES. 
Page. 
General methods of control 29 
Habits and seasonal history as suggesting methods of control 29 
Destruction of the broods 30 
Barking the standing trees to kill the broods 30 
Destruction of the broods without removing the bark 30 
Attempts at complete extermination of the beetles unnecessary 31 
Requisites for successful control 31 
How to check and control an extensive invasion 31 
How to control a limited attack 32 
How to maintain control 32 
In State and National forests . . * 32 
In private forests 32 
Inaccessible areas 33 
Trap-tree method of control 33 
Introduction and protection of natural enemies 34 
Importance of systematic forestry 35 
Some results of efforts to control beetle depredations 35 
Detailed information on the species 38 
General explanation of descriptive and other terms 38 
No. 1. The western pine beetle {Dendroctonus brevicomis Lee.) 42 
Seasonal history 42 
Overwintering stages 42 
Activity of overwintered broods 42 
First generation 43 
Second generation 44 
Habits 44 
Economic features 45 
Evidences of attack ' 45 
Effects on commercial value of the wood 46 
Favorable and unfavorable conditions for the beetle 46 
Methods of control 46 
Basis of information 49 
Bibliography 49 
No. 2. The southwestern pine beetle {Dendroctonus barberi Hopk.) 49 
Seasonal history 50 
Overwintering stages 50 
Activity of overwintered broods 50 
First generation 50 
Second generation 51 
Economic features and methods of control 51 
Basis of information 52 
Bibliography 52 
No. 3. The roundheaded pine beetle {Dendroctonus convexifrons Hopk.) 53 
Seasonal history 53 
Overwintering stages 53 
Activity of overwintered broods 53 
Generation 54 
Habits 55 
Economic features 55 
Methods of control 55 
Basis ot information 56 
Bibliography 56 
