CARPENTERS AND WOOD-WORKERS 113 



begun by the insignificant beetle. It must be 

 understood that when we speak of carpenter beetles 

 we really refer to the insect in the grub stage.. 

 Some of the beetles as perfect insects indulge in 

 wood-boring to some ^'extent, especially females 

 to deposit their eggs in a suitable position, but 

 the real work of wood-boring is performed by the 

 larvae. 



These insects are little known to any but the 

 coleopterists, owing to their secluded lives. One 

 whose ravages are most familiar is the Bark Beetle 

 (Scolytus destructor), because one can often see a 

 dead elm from which the bark has fallen, revealing 

 the characteristic feather-like sets of burrows. 

 There is a central burrow from which on either side 

 other burrows run off at right angles to the central 

 burrow, and at first parallel to each other. This 

 pattern is brought about in this manner : the 

 mother beetle bores the central burrow, and lays 

 her eggs to the number of about fifty at pretty 

 regular intervals along each side of it. When these 

 eggs hatch, the young grubs set to work, each 

 forming one of the side galleries. It is remarkable 

 that every one of them should start off at a right 

 angle and continue his burrow away from the 

 central avenue. 



These side galleries as they advance from the 

 centre increase in breadth, an indication of the 

 gradual increase in size of the carpenter. To 

 accommodate this extra width without the whole 

 of the side-burrows coalescing at their ends, it is 



