146 COMMON BRITISH INSECTS. 



longitudinally, and the thorax is very large in pro- 

 portion to the size of the insect, and is covered with 

 very small punctures. The elytra are sometimes 

 black, sometimes pitchy, and sometimes bright-chest- 

 nut, and are striated, the spaces between the striae 

 being punctured. So much for the appearance of 

 this Beetle we will now proceed to its history. 



When the mother Scolytus is about to deposit her 

 eggs, she flies to a tree, and searches about the bark 

 for a favourable spot. Having foun d it 

 she sets to work and gnaws a hole com- 



Ipletely through the bark, until she gets 

 between the bark and the solid wood. 

 /Jl l\ "^ e next drives a tunnel, scarcely 

 /^tewY wider than her own body, and then 

 " goes back along the tunnel, and de- 



Scolytus destructor. pQsits her ggs along j t j n many 



cases she exhausts all her life-powers in the effort, 

 and dies before she can entirely escape from the burrow, 

 the entrance of which is stopped up by her body, so 

 that no foe can enter. 



The eggs are soon hatched, and then the larvae 

 begin their destructive work. They feed on the soft 

 inner bark, and each larva, as it feeds, instinctively 

 turns itself at right angles to the burrow in which it 

 was hatched, and gnaws for itself a tunnel, which 

 widens in proportion to the growth of the larva. 

 These burrows extend for an inch and a half or two 

 inches in length, and the result is, that a piece of 

 bark, some three inches or more in diameter, is com- 

 pletely severed from the tree, and can no longer per- 

 form its office. At the widened end of the burrow 



