DAMAGE CAUSED BY ANIMALS. 141 



cally the same as with regard to B. typographus, but with this 

 difference only, that more careful attention must be given to the 

 younger classes of woods. 



67. The large 12-toothed Pine Bark-beetle, Bostrichus stenographus 

 (Tomicus sexdentatus). 



(Vide Plate I. fig. 6.) 



This is the largest of the bark-beetles; it varies from 0'22 



to 0*32 inches in length. It is of a glossy black or deep brown 



I colour, with yellow hairs, and narrows towards its lower end. 



I The elytra are deeply grooved and punctured, and pinched in where 



they curve downwards; they have 6 tooth-like projections (i.e., 



|| 12 in all) on each side, of which the fourth is the 



; longest. 



Notwithstanding its size, it is one of the less injurious species 

 j of bark-beetles, for it almost always deposits its ova in felled 

 \\ timber only, in windfall stems, or the ordinary falls prepared for 

 I sale as timber or fuel, and confines itself almost entirely to old 

 I and thick barked Scots Pines or the species closely allied 

 j thereto ; it is found only exceptionally on the Spruce. When, 

 j however, such timber cannot be found, it also, driven by necessity, 

 j attacks standing timber. Such devastations as have been com- 

 j mitted by the Spruce bark-beetle have never yet been chargeable 

 to this insect, which is even comparatively rare in some parts of 

 | the vast Pine forests of northern Germany. 



In habits and life-history it resembles the Spruce bark-beetle 



in many respects. It swarms in April and May. The main 



I galleries are vertical, and attain a length up to 8 inches and 



more on each side of the entrance-hole, hardly, if at all, penetrat- 



I ing into the sap wood. Its generation was formerly considered to 



; be merely simple, but recent observations seem to prove that it is 



also double. 



Special measures will seldom require to be adopted against this 

 j insect, as the barking of any timber that may have been attacked 

 usually suffices to confine its occurrence within non-injurious 

 limits. 



