6 



wood may be a necessity for egg formation. No eggs are laid at 

 this time, nor are the eggs ever laid in new wood. After feeding 

 for ten days or two weeks on the new wood, the beetles mate and 

 the females go to the old wood to deposit their eggs. If confined 

 on/ young twigs when it is time to lay eggs, the beetles riddle the 

 bark with punctures, but will not place the eggs in the holes. 

 This peculiarity of the insect in laying eggs only in old wood is 

 brought out clearly by a common nursery practice. A cutting 

 of one year wood is rooted and allowed to grow from one bud. 

 The following year this shoot and the tap root are pruned and the 

 stock replanted. At the end of another year this is called a one- 

 year-old tree, though it may have six or eight inches of two-year- 

 old wood above ground. If such trees are infested, as they 

 frequently are, the eggs are invariably inserted in this short sec- 

 tion of old wood. 



Since the larvae spend their entire lives beneath 

 How the bark and eat parts of the plant that we can 

 control not reach with poison, there is but little hope of 

 the pest. control through the use of such materials. It was 

 thought possible that something might be accom- 

 plished by the use of contact sprays; so several applications of 

 such sprays were made, mostly of lime, kerosene and arsenic in 

 combination. These were applied in the winter in the hope of 

 suffocating the hibernating larvae, but in no case was there any 

 appreciable effect. 



Failure of these remedies leaves but one thing to be done 

 against the larvae ; that is to cut out and burn the infested parts 

 in June, before the beetles emerge but while they are actively at 

 work and reveal their presence by the collections at the mouths 

 of the tunnels. When only a few trees are infested this method 

 is not difficult to apply and gives quite effective control. 



The vulnerable point in the life history of the insect is the feeding 

 of the beetles. Since, to get at their favorite food, the cambium, 

 they must eat holes in the bark, the use of a coating of poison upon 

 the young twigs promised some relief. To test this quite extensive 

 " laboratory " tests were made, with excellent results; but oppor- 

 tunity has not yet been given to apply the same method in actual 

 field work. However, it seems probable that the spraying of 

 nursery blocks with poison will be both effectual and inexpensive. 



