I 12 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



The Pine Beetle (Myelophilus piniperda). 



The damage done to Scots pine plantations by this insect is 

 now well known, but one important aspect has probably been 

 overlooked. The injury to lateral shoots on healthy-growing 

 trees will undoubtedly aggravate the shortage of seed, in the 

 vicinity of felled areas, where the lop and top has, for any 

 reason, been allowed to form a breeding-ground for the beetle. 

 That a serious loss in timber increment occurs, where a bad 

 attack has taken place, has been admitted for some time, and 

 the characteristic appearance of the crowns on the margin of 

 a felling area is known to most foresters. But, while it is 

 evident that a loss of foliage must react on the crop of cones, 

 the writer is not aware of any literature on the subject. 



After the recent heavy fall of snow (November 19 19) had 

 disappeared, a heavy litter of short twigs was observed on the 

 floor of an area of vigorous-growing Scots pine, and as felling 

 had been going on for the last two years on an adjoining area, 

 it was not surprising to find that the pine beetle had been busy. 

 The snow was unaccompanied by wind, and, being moist, clung 

 to the close crowns for some days, the weight ultimately snapping 

 the twigs where they had been weakened by the entrance-holes 

 made by the beetle. The unusual feature was the number of 

 twigs found with cones attached. One, two, three, and even 

 larger clusters of mature (two-year) cones were observed, and 

 even a few specimens of one-year growth were in evidence. A 

 closer inspection showed that a slight attack of the beetle had 

 taken place during the late summer months of 1918, not severe 

 enough to prevent the maturing of the then one-year crop of 

 cones, but sufficient to check, to a certain extent, the formation 

 of the succeeding year's crop. This corresponds with the fellings 

 that were being carried on, part of the adjoining area being 

 exploited during the spring and early summer of 1918 and part 

 at the same periods of 19 19. It is evident that the later broods, 

 hatched out in 1918, took to the crowns of the adjoining trees 

 in the autumn, and returned to the new fellings in the spring 

 and early summer of 19 19, the bulk of the logs and brushwood 

 of the earlier felling having been cleared by that time. That 

 the beetles have returned to their old winter quarters in 

 augmented numbers is apparent. Even if there is no further 

 felling in the neighbourhood, a few years must elapse ere the 



