. INSECTA. 249 



Fig. 167. — The Hive Bee (Apis mellijica). ^ . 



Drone 6 . 



Queen $ . 

 Three sorts of individuals. 



Worker or Neuter. 



and the workers, which are sterilised females. In the ants 

 the workers have no wings. 



The gall-fly lays its eggs on plants and the " gall " is 

 produced by the* plant around the egg. The insect escapes 

 from the "gall" by a small hole. The ichneumon-flies 



Fig. 168. — The Gall-fly {Cynips qiiercus-folii). 



The galls are shown on the left, the interior of a gall on the right, and the 

 perfect fly below, 



are of economic value from their habit of laying eggs in 

 caterpillars of certain Lepidoptera. The larvae feed on the 

 substance of the caterpillar and eventually kill it. The 

 saw-flies have larvae somewhat like caterpillars but with more 

 legs. They are sometimes called " false " caterpillars and 



