142 PROTECTION OF WOODLANDS. 



68. The 2-tootked Pine Park-beetle, Hostrichw bidens (Tomicus 



bidentatus). 



This little beetle, from 0'08 to 0'092 inches in length, is black, 

 glossy, and covered with fine hairs. The elytra are frequently 

 dark brown, with fine rows of punctures ; towards their termina- 

 tion on the male there is a broad flat indentation, on the upper 

 edge of which a large curved tooth-like projection protrudes on 

 both elytra (hence bidens), that is wanting on the female. 



This insect is chiefly to be found on the Scots Pine, and on the 

 various species of Pine generally, although it also attacks Spruce and 

 even Larch when it cannot find suitable breeding-places on the 

 former. 



It principally attacks young crops about 10 to 12 years of age, 

 or else the crowns and branches of poles and trees where the 

 bark is thinnest, avoiding as far as possible the portions where the 

 bark is thicker. It must be included amongst the very injurious 

 class of insects, for it has often been the cause of the ruination of 

 very extensive plantations and young seedling growth, as well as 

 of thinning and interrupting the canopy of old Pine woods to an 

 injurious extent. 



Swarming in April or May, it also has a double generation. 

 The main galleries radiate in a star-shaped manner, but are easily 

 distinguishable from those of B. chalcographies by their greater 

 irregularity, whilst both the main and the larval galleries bite into 

 the sapwood to a certain extent, and the pupal chamber is 

 embedded within it to a very considerable degree. 



The first generation is usually fully developed by the end 

 July, when it proceeds to reproduce itself in a second generatioi 

 Under favourable circumstances this can also reproduce itself 

 a third generation that hibernates in the larval state ; but undt 

 normal circumstances, the beetles of the second generation 

 a rule hibernate before reproducing themselves. 



The best means of operating against B. bidens is by keeping tl 

 woods clean and well-thinned, removing all sickly poles during tl 

 thinnings, and by laying down small wood, the branches ai 

 twigs of decoy-stems set for other kinds of bark-beetles, for tl 

 purpose of attracting the beetles thereto, and then burning it 

 removing it from the woods as soon as the ovi-deposition is at 

 end. Young seedlings or saplings that have been attacked shou] 



