358 



MANUAL OF ZOOLOGY. 



tion, which is often spoken of as that of the Terebrantia, as the 

 females have the ovipositor converted into a saw or borer. 

 The larvae of the Saw-flies (fig. 191) feed upon vegetable 



matter, and have pro-legs. 

 Another important group 

 is that of the Gall -flies 

 (Cynipida), all of which 

 lay their eggs in the soft 

 tissues of plants (generally 

 the leaves). The result- 

 ing "galls" are due to the 

 abnormal cell -growth ex- 

 cited locally in the plant 

 by the irritation caused 

 by the puncture of the 

 mother's ovipositor in 

 depositing the eggs. The 

 larvae are footless. In the 

 allied group of the Ich- 

 neumons (Tchncumonidce), 

 the larvae are also footless, 

 and the eggs are deposited 

 by the females in the larvae 

 or pupae of other insects, 

 upon whose tissues the 

 young support themselves 

 after hatching All the 

 other Hymenoptera have 

 the ovipositor of the female converted into a sting (not always 

 the case in the Ants), and they may therefore be grouped 

 together under the common title of Aculeata. The principal 

 families included under this name are the Ants (Formicid<z), 

 the Wasps (Vespidce), the Hornets (Crabronidce), the Bees 

 (Apid<z\ and the Bumble-bees (Bombida}. 



Amongst the Hymenoptera we find social communities, in many respects 

 resembling those of the Termites, of which a description has already been 

 given. The societies of Bees and Ants are well known, and merit a short 

 description. 



The social Bees, of which the common Honey-bee (Apis mellifica), is so 

 familiar an example, form organised communities, consisting of three classes 

 of individuals the males, females, and neuters. As a rule, each commu- 

 nity consists of a single female "the queen" and of the neuters, or 

 " workers." The impregnation of the female is effected by the production 

 of males, or "drones," during the summer. After impregnation has been 

 effected, the drones, as being then useless, are destroyed by the workers. 

 The eggs produced by the fecundated queen are mostly intended to give 

 origin to neuters, to which end they are placed in the ordinary cells. The 



Fig. 191. Gooseberry Saw-fly ( Tenthredo grossu- 

 lartce), larva, pupa, and imago. 



