1913 ENTOMOLOGICAL SOCIETY. 89 



Pissodes in young growth. The effect of an old Pissodes injury to spruce is evi- 

 dent in numerous " double-tops " throughout the Riding Mountain Reserve, Mani- 

 toba. 



Dendroctonus murrayanae, Hopkins, and other destructive bark-beetles, to- 

 gether with many injurious buprestid and cerambycid borers are very abundant in 

 the Riding Mountain Forest Reserve, Manitoba. 



Only a limited amount of cutting is allowed in the reserve, and this is chiefly 

 in fire-swept areas. There were several considerable bums in the spring of 1911, 

 and in these the bark-(beetles were present in spruce and pine in immense num- 

 bers. There were no fires of importance in the reserve this spring, and consequently 

 little cutting of green timber. There is danger of an outbreak of bark-beetles of 

 the genera Dendroctonus and Polygraphus in the neighbourhood of these 1911 fire 

 areas. One of these species (Dendroctonus murrayanae, Hopk.) has already de- 

 stroyed some timber there; but it is not noticeably common in healthy trees. A 

 few Dendroctonus-killed jack pines may be seen along the Clear Lake trail. Condi- 

 tions are being carefully watched by the officers of the reserve and any outbreaks 

 will receive prompt attention. 



The Larch Dendroctonus, D. simplex Lee, is very common throughout the 

 parts visited. It was found in great numbers in dead, standing larches ; but whether 

 or not it had been the primary cause of the death of the trees could not be then 

 determined. This species prefers bark in a dying condition, but may become an 

 important auxiliary of the larch saw-fly in future years. Ips perturhatus, Eichh., 

 and Ips caelatus Eichh., are very abundant in fire areas south of Clear Lake. They 

 are found there chiefly in white spruce, which was badly injured by fire. Poly- 

 graphus rufipennis Kirby, the spruce bark-beetle, is common everywhere in dying 

 bark of spruce, larch, and jack pine. These species are aible to kill weakened or 

 injured trees which might otherwise recover. Other species of bark-beetles of lesser 

 interest are abundant in dying bark of spruce, pine, and larch. 



Timber-lbeetles of several species are plentiful. Trypodendron retusus Lee, 

 the poplar timber-beetle, in poplar, and T. lineatus, Ratz., the spruce timber-beetle, 

 in spruce and pine, are the most common. These beetles drive their small round, 

 black tunnels more or less deeply into the wood of dying or recently killed trees 

 and logs, or freshly-cut lumber, and reduce its value for all but cheaper purposes. 

 They also assist in the introduction of fungi and bacteria into the wood. Many 

 poplars on the upper plateau are more or less scraped by deer. These scrapings 

 penetrate to the cambium, and present an ideal inoculation-surface for fungi and 

 bacteria. The poplar timber-beetle enters later on these scraped surfaces, and 

 through its tunnels spores may reach deeper layers. 



Damage to killed and injured spruce and pine by cerambycid and buprestid 

 borers is extensive. Piled lumber cut in the fire areas by portable mills showed 

 abundant evidence of their borings. The fires occur usually early in the spring. 

 These beetles lay their eggs in slits or crevices in the bark late in June and in 

 July. They seldom deposit their eggs on barked surfaces. The grubs cut large, 

 rounded and flattened tunnels through the bark and wood. 



To prevent the injury by these borers it is necessary to bark the trees, or put 

 them in water when possible, before the young grubs have worked through the bark 

 and into the wood, or to saw before they are deeper than the thickness of the slaJb. 

 Some species will continue their borings in piled lumber, or even in parts of build- 

 ings, for months or even years, if they have penetrated deeply before the logs were 

 eawed. 



