CONTENTS. 



Page. 



Introductory ^^ 



Historical -^ 



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 i -. 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 



