HYMENOPTEEA. 171 



these the Sawfiies and the Sirioes are very destructive ; Ants 

 and "Wasps are sometimes noxious ; whilst the Ichneumon-flies 

 and Chalcid-flies are parasites, hundreds of species living upon 

 other members of the insect world and so doing much good. 



The Hymenoptera have both biting and sucking mouth-parts, 

 a completely fused prothorax, and four membranous wings with 

 few nervures and a dark stigma on the costa. Metamorphosis 

 is complete. The head is provided with two large, compound 

 eyes, and three ocelli on the vertex. The upper lip and 

 mandibles are short, the mandibles being used for biting as in 

 beetles. Maxillie may be elongated, and long in those that 

 suck up the nectar of flowers. The lower lip may form a long 

 tube with the maxillae, which is bent round in repose. In bees 

 the tongue can be so elongated as to assume the form of a pro- 

 boscis : in this case the lobes of the jaws become elongated, and 

 form a sheath for the tongue. On the base of the fore-wings 

 are found two scale-like bodies, the tegulcB. In Wood Wasps 

 {Uroc&ridce) and Sawflies {Tenthredinidce) the pronotum is not 

 united with the mesonotum. The wings are sometimes united 

 together when expanded by a row of hooks. Wings may be 

 absent (MutiUd), and in some of the workers, amongst the 

 social Hymenoptera. The abdomen of the female may end in 

 a sting, a saw, or ovipositor. The larvae are 

 of two types ; generally tliey are apodal. The 

 apodal forms pass their life as parasites in the 

 body of other insects or in plants, producing 

 "galls,'' or in cells in the nests of the social 

 and gregarious Hymenoptera. The sawfly larvae 

 or " False-caterpillars " somewhat resemble those 

 of the Lepidoptera, but there are six to eight 

 pairs of abdominal legs, and they live free on ^'"'A^SAwrLYf "* 

 leaves or in galls. The larvae of the Wood 

 Wasps {Siiices) live inside the wood of trees, and have only 

 rudimentary legs. The grubs of social Hymenoptera are fed 

 by the workers ; they have a small, brown, retractile head, 



