and death is due to repeated attacks of several species of 

 beetles. 



Tracing Cause of Infestation. 



Forest officers, after determining that a tree is 

 dying from insect attack, muat next locate the insect doing 

 the damage. To do this one must become familiar with the 

 method of attack of the most important species, the design "f 

 their galleries, etc. Host of the destructive killing con- 

 ifers are beetles or hardshelled insects. Since the life hirs- 

 tory of each species plays a most important part in control 

 work, it is important that Forest officers should understand 

 the various phases of development in the life of a beetle. 

 These are four in number: The egg, the larva or grub, the 

 pupa or dormant stage, and tLo adult or imago. All growth is 

 confined to the larval stage and, therefore, most of the in- 

 jury is done in this period of a beetle's life. The adult 

 stage is the only other period in which the insect injures a 

 tree. Beetles may be relatively large or small, according to 

 the food suppler during the grub stage. Most species can be 

 told by the design of the gallery, many by the method of de- 

 positing the eggs, the species of tree or the part of the tre ; 

 attacked. Some may be told by the color or character of the 

 pitch tubes. Of course, such identifications are not absolute; 

 The identification <-if the actual fully developed beetle or 

 imago is the only absolute proof. 



