CONTENTS. 



PAGE 



Introduction 7 



I. The Beetles and Their Habits 8 



The Life Stages 



General Habits .- 9 



Aberrant Habits ' 9 



The Details of the Tunnels 10 



The Entrance Hole 10 



The Entrance-tunnels 11 



The Egg-tunnels proper 11 



The Ventilation-tunnels 12 



The Egg-niches 14 



The Egg-pockets 14 



The Egg-grooves 14 



The Turning-niches 14 



The Nuptial Chamber 14 



The Food Tunnels 15 



The Types of Egg-tunnels 16 



The Larval-mines 18 



Factors Influencing the Development of Bark-beetles 18 



Oviposition 19 



Removing the Boring-dust 19 



A Method for Studying Habits 20 



II. Bark-beetle Injuries and the Means of Control 22 



Bark-beetle Injuries 22 



Primary Enemies 22 



Secondary Enemies 23 



Neutral Species 23 



The Importance of Bark-beetle Injuries in Canadian Forests 23 



The Normal Annual Loss 23 



Sporadic Outbreaks 24 



Epidemic Outbreaks 24 



Conditions Favouring Bark-beetle Outbreaks 25 



Slash . 25 



Ground Fires 25 



Other Factors 26 



Natural Control Factors 26 



Parasites 26 



Predators 26 



Birds 27 



Parasitic Fungi 27 



Methods of Control 27 



The Interrelations between Fire and Bark-beetles 28 



III. Structural Characters of the Bark-beetles 30 



General Characters of the Body 30 



The Head 30 



The Thorax 32 



The Legs 33 



The Elytra 33 



The Abdomen 33 



Internal Characters 34 



IV. Classification. A Preliminary Arrangement of the Canadian Bark-beetles 35 



Introductory 35 



Paired Species 36 



The Superfamily Ipoidea 38 



The Family Platypodidae 38 



The Family Ipidae 38 



The Subfamily Eccoptogasterinae 39 



The Subfamily Hylesininae 39 



The Subfamily Micracinse 44 



The Subfamily Ipinae 44 



List of Coniferous Host Trees 134 



Glossary 134 



References to Literature 139 



Index to Genera and Species and to the Plates 140 



5 



