THE ANIMAL KINGDOM. 217 



family sometimes covers a large part of the surface of a 

 tree, and if the species multiplies round about it the result 

 of its work is to detach the entire bark, which falls to dust. 

 The attentive observations of foresters have shown that 

 nearly always a pair of typographer beetles enter the tree 

 together by perforating the bark, and this first task accom- 

 plished they hollow out at this spot a central gallery, which 



109. Cone Pyralis : Tortrix Strobiliana. Caterpillar and Butterfly, enlarged and of 



natural size. 

 Section of Fir Cone to display the work of the Caterpillar. 



is nothing more or less than a nuptial chamber for the pair. 

 Here, resolved to make their lives as agreeable as possible, 

 they pierce, for this purpose, two to four holes in the bark, 

 which are simply ventilators, intended to air the little 

 chamber, and possibly also to light the windings. The 

 female lays her eggs all along the chamber, producing from 



