36 PROTECTION OF PLANTS, 1921-22 



The Balsam Bark Weevil, Pissodes duhius Rand., is a greyish snout beetle, 

 with whitish markings, about one-quarter of an inch in length. The beetles ap- 

 pear in the spring and deposit eggs in groups of punctures in the bark of the trunk 

 of standing balsams. The resin which exudes from the punctures hardens and 

 forms whitish patches on the bark which are more or less characteristic of the 

 injury. The larvae which hatch from the eggs excavate very long mines in the 

 inner bark, from six to twelve inches in length, radiating from the group of egg 

 punctures, and left filled behind the larvae with reddish excrement. The larvae 

 are about one-quarter of an inch in length when mature. They pupate in the 

 ends of the tunnels and eventually emerge through individual exit tunnels cut 

 through the overlying bark, leaving a round exit-hole. 



This species does not oviposit in dry trees or old slash. It attacks weakened 

 balsams and may affect trees showing little evidence of being unthrifty. The 

 work of this species is easily distinguished from that of the Balsam Bark-beetle 

 through the absence of egg-tunnels, the larger grubs, and the longer, larger 

 mines, radiating from the egg-punctures. 



Control 



When we commenced our study of this problem the primary budworm 

 outbreak was over, in the greater part of Quebec Province, and the secondary 

 bark-boring beetles were attacking the weakened and dying trees. There was^ 

 therefore, no possibility of controlling the budworm; its work was already done. 

 It should be clearly understood that the problem we have now to deal with in 

 Quebec, except for the extreme western section, is not at present the control of 

 a budworm outbreak, but rather the control of the beetles which followed the 

 budworm, the salvage of the standing and dying and weakened balsam and the 

 development of a system of forest management, supplemented by possible direct 

 control, which will prevent another calamity from the same cause in the years to 

 come. 



Our aim has been to obtain all information available regarding the injury,, 

 the factors which affected its rise and fall and to determine some methods of 

 avoiding the greatest loss from the next budworm attack. We may not have 

 another outbreak for a generation, or more, but when it does come these condi- 

 tions will probably obtain; the percentage of balsam in Quebec forests will be 

 very much higher than it was 10 years ago and our pulp industrj^ will be depend- 

 ent very largely upon balsam for its wood supply. This high percentage of bal- 

 sam will invite a very heavy injury; but if we can manage to have a healthy 

 stand of growing balsam without large areas of mature and overmature timber 

 or if the percentage of spruce in the coming stands can be increased, the effects 

 of an outbreak will probably be much less destructive. 



