THE SPRUCE INVESTIGATION. 243 



trees, logs, tops and stumps, more inviting breeding places for 

 its next greatest enemy the spruce bark-beetle. Thus it would 

 appear that the present great destruction of timber- by lumber- 

 men is at least having one good effect that of attracting to the 

 various fields of operation, the surplus of all those insects which 

 may breed in dying, or storm-felled trees in the virgin area, 

 and in this manner the living trees are protected from their at- 

 tack. A general discontinuance of operations in the spruce 

 area would probably be followed by fatal consequences to the 

 living trees, on account of the swarms of the spruce bark beetle 

 and their allies, which would doubtless invade the living tim- 

 ber when they failed to find a supply of recently felled trees 

 and tops in which to breed. 



The present serious injuries to the spruce by insects is con- 

 fined to the timber injured by fire, recently felled, or cut into 

 saw logs. If such timber is allowed to remain standing, lying 

 on the ground, or in skidways, with the bark on, for a few 

 weeks, between the first of April arid the middle of September, 

 it will be attacked by wood boring species which may mater- 

 ially depreciate its value for lumber. If allowed to remain 

 thus through the summer, it may be rendered almost worth- 

 less by the wood boring insects for anything butpulpwood. 



The living timber is not, it must be remembered, entirely 

 safe from another destructive invasion of insects since a series 

 of favorable conditions, as of succesive warm winters, excessive 

 and long continued drouths, unusually severe hail and wind 

 storms, together with a diminution of the parasites and other 

 natural enemies of the destructive insects, may be the means 

 of starting another serious trouble like that recently exper- 

 ienced in the pine forests of this and adjoining States. Thus, 

 the importance and necessity of owners of spruce forests keep- 

 ing a vigilant watch for all indications of trouble, and when any- 

 thing of the nature we have mentioned is observed, this 

 department of the Experiment Station should be informed 

 about it, without delay, in order that we may extend such ad- 

 vice or assistance towards preventing the loss of timber as may 

 be in our power. 



