' 



Bend root onus generally produces pitch tubes, the 

 Ips granulated pitchy .sawdust. Flat ho arts and roundheads, 

 however, do not leave any pitch tubes or sawdust on the outer 

 bark. The eggs are laid in the crevices. The minute grub 

 enters the inner layers through the cor 1 : bar!:, but it is so 

 small as to leave no visible entrance, 



The egg galleries of Dendmctonus are almost al- 

 ways filled with sawdust and seldom have egg notches, while 

 Ips galleries are generally clear of sawdust, and havr egg 

 notches on the sides. Nothhes for depositing the eggs:-are 

 also common in galleries of some nf the smaller baric -borers, 

 such ap Pifcyophthorus, Eccoptogaster, etc. 



Secondary Insects. 



Secondary insects either follow up the initial 

 attacks of the primary insects or attack individual twigs or 

 branches on otherwise healthy trees. They may be primary in 



* 



milling chese twigs and branches but are not primary in kill- 

 ing the tree. There are numerous species on each species of 

 tree. Many insects, although using conifers as hosts, do not 

 injure the tree. Bees (of the order Hymenoptera) and many 

 weevils or snout beetles (of the order Colooptera.) belong to 

 this group and live mostly in the c<^r<; bark. : :hers, (of u hr 

 order Coleoptera) , enter the inner layers or", the bar 1 : imrie- 



-38- 



