THE SEQUOIA PITCH MOTH. 7 



of the other side is several inches above ground. Under no circum- 

 stances is the tunnel parallel to the grain of the wood. 



As stated, the activity of the larvse within the cambium of the tree 

 causes a heavy flow of pitch toward the exterior, and fresh, flowerlike 

 nodules upon older exudations (fig. 3) are a definite proof that the tree 

 is still infested. 



EFFECT OF THE INFESTATION ON TREE GROWTH AND THE FOREST. 



It is obvious that with one-half and, in the majority of cases, two- 

 thirds of the circumference of the tree trunk cut off from the root 



Fig. 4. — Stump of a pine tree 64 years old which grew to be 9| inches in diameter breast high at 41 years 

 of age and added only seven-eighths inch to this diameter during the last 23 years of its life, owing to 

 attack by the Sequoia pitch moth. (Original.) 



system by the dividing tunnel, the growth of the afflicted tree has to 

 suffer. Count of annual rings and measurements on a tree which was 

 considered to be a fair example of the general injury in the area 

 brought out the fact that during the first 41 years of its life and nor- 

 mal health it had added annually about one-fourth inch to its diam- 

 eter, while it added only about one thirty-second of an inch, or the 

 thickness of an ordinary visiting card, annually during the 23 years 

 it had been infested by the pitch moth. (See fig. 4.) 



