31 



tioiis, tlievi the removal of the bark I'roiii infested liees in and accessi- 

 ble to the regulai- siunmer euttiui^s at a time wlu^n it is filled with the 

 young- stages of the insect is practicable, and may alone, with little 

 additional expense, conti-ibute greatly to the reduction of the pest. 

 In no case, however, would it be necessary to burn the bark, either in 

 summer or Avinter. The greater number, if not all, of the insects 

 would perish from the drying of the bark in the snmmer, freezing in 

 winter, and from the attack of birds and other enemies. It is true 

 that some of the adults may escape in the summer to attack other trees, 

 but it is believed that little trouble would resnlt from this source. 



DESTRUCTION OF DEAD TREES. 



This is another method which is often recommended for the pre- 

 vention of depredation by insect enemies of forests, meaning in many 

 cases trees whicli have been dead a long time, as well as stumps and 

 logs in which it is supposed destructive insects breed. As applied to 

 insect enemies of living trees, or those which make the x)i*iniary attack 

 in living bark, the destruction of old dead trees, stumps, and logs 

 would be worse than useless, since all of the really dangerous ene- 

 mies emerge from the ti'ees either before thej^ are entirely dead or 

 within one year after they die. The only appai'ent advantage to be 

 gained as apjilied to the sj)rnce would be the destruction of a few of the 

 insect depredators on the wood of dead trees, and in this it would be the 

 most exceptional cases wiiere there would be any appreciable benefit. 



GIRDLING TEEES. 



This is an old method practiced in Europe and quite extensively 

 recommended, but, like most other methods, it is only applicable to 

 certain kinds of insects and depends on specially favorable conditions 

 for its desired effect. 



INVESTIGATION OF THE GIRDLED-TREE METHOD. 



Some evidence found in the telled and diseased standing trees on 

 the first and second days of the investigation, in the vicinity of 

 Wight's camps, suggested to the writer the importance of experi- 

 ments to determine the relation of girdled trees to the attraction of 

 the insects away from the living; thei-efore, the girdling of large 

 spruce at different dates during the summer was recommended to 

 Mr. Cary as an important line of work for him to undertake. 



HACK-(iIRDLED AND PEELED SPRUCE. 



This subject was kept in mind throughout the investigation, and 

 some good opportunities were had at different places to study the influ- 

 ence of the common practice of sportsmen, loggers, and surveyors — 

 hack-girdling and peeling spruce to obtain the bark foi-camp covering. 



In the vicinity of Lincoln l*ond large numbers of peeled spruce 

 were examined on May 30. The larg<'i' number of these had been 

 peeled, as we were informed by the loggei-s, in July, 181)8, and had 



