CONTENTS. 



Page. 



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 



