CONTENTS 
Introductory 1 
Historical 1 
Destruction caused by the beetles 3 
Character and extent of depredations 4 
Possibilities of control 4 
The beetle problem as important as the fire problem 5 
Distinctive characters of the genus 5 
Adult characters 7 
External sexual characters 7 
The egg 10 
The larva 10 
The pupa 11 
Egg galleries, larval mines, and pupal cells 12 
Distribution 14 
Host trees 15 
Evidences of attack 17 
Seasonal history 18 
Influences of latitude and altitude on seasonal history 19 
Habits 21 
Habits of parent adults and of immature stages 21 
Relation of habits to successful control 21 
Secondary injuries to the trees 22 
Favorable and unfavorable conditions for the beetles 22 
Climatic influences 23 
Drought 23 
Low temperature and snow 24 
Lightning 24 
Wind storms 24 
Other influences and conditions 24 
Forest fires 24 
Matured timber 25 
Commercial cutting 25 
Summer cutting 25 
Winter cutting 25 
Natural enemies of the beetles 26 
Insects 26 
Birds 27 
Diseases of the insects , 28 
Diseases of the trees 28 
Secondary enemies of the trees, and dependents, guests, etc., of the destructive 
beetles 29 
VII 
