Sirex gigas ; an insect which, in the larva state, is very destructive to fir timber . 



CHAPTER IV. 



OF THE CLASSIFICATION OF HYMENOPTERA. 



THE metamorphosis in the third class, Hymenoptera, is 

 necromorphous. The larva bears no resemblance to the 

 imago ; it has small corneous mandibles, moving horizon- 

 tally ; in seven orders it has six articulate, and from twelve 

 to sixteen prehensile feet ; in the remaining orders it is 

 without feet. Pupa quiescent, having the organs of loco- 

 motion and manducation confined by a shell -like skin ; yet 

 displaying all the limbs and organs, placed in order by the 

 sides of the body, and detached from it, except at the usual 

 points of connexion. Imago with the mandibles strong, 

 moving horizontally, and masticatory ; the other organs of 



