216 Insect Architecture. 



flat retractile tube, which she inserts between the bark 

 and the wood, to the depth of about a quarter of an inch, 

 and there deposits a single egg. By stripping off the bark, 

 it is easy to trace the whole progress of the grub, from the 

 spot where it is hatched, to that where it attains its full 

 size. It first proceeds in a serpentine direction, filling the 

 space which it leaves with its excrement, resembling saw- 

 dust, and so stopping all ingress to enemies from without. 

 When it has arrived at its utmost dimensions, it does not 

 confine itself to one direction, but works in a kind of 

 labyrinth, eating backwards and forwards, which gives the 

 wood under the bark a very irregular surface : by this 

 means its paths are rendered of considerable width. The 

 bed of its paths exhibits, when closely examined, a curious 

 appearance, occasioned by the gnawings of its jaws, which 

 excavate an infinity of little ramified canals. When the 

 insect is about to assume its chrysalis state, it bores down 

 obliquely into the solid wood, to the depth sometimes of 

 three inches, and seldom if ever less than two, forming 

 holes nearly semi-cylindrical, and of exactly the form of 

 the grub which inhabits them. At first sight one would 

 wonder how so small and seemingly so weak an animal 

 could have strength to excavate so deep a mine ; but when 

 we examine its jaws, our wonder ceases. These are large, 

 thick, and solid sections of a cone divided longitudinally, 

 which, in the act of chewing, apply to each other the 

 whole of their interior plane surface, so that they grind 

 the insect's food like a pair of millstones. Some of the 

 grubs are hatched in October ; and it is supposed that 

 about the beginning of March they assume their chrysalis 

 state. At the place in the bark opposite to the hole from 

 whence they descended into the wood, the perfect insects 

 gnaw their way out, which generally takes place betwixt 

 the middle of May and the middle of June. These insects 

 are supposed only to fly in the night, but during the day 

 they may generally be found resting on the wood from 

 which they were disclosed. The grubs are destitute of 

 feet, pale, folded, somewhat hairy, convex above, and 



