ORDER HYMENOPTERA. 



21 



these cases the outer covering of the nest is thinner and more 

 delicate in texture than when the dwelHng is exposed to the 

 vicissitudes of the weather. Another common species inhabiting 

 Britain is the Wood Wasp ( Vespa sylvestris), which builds nests 

 suspended from the branches of trees. 



Family 4, Eumenid(^. — One of the commonest and best-known 

 species belonging to this family is the Wall Wa^p {Odynerus 



Fig. 19. — Odynerus Ovalis (Mag.) 



partefum), which may be almost constantly seen haunting sunny 

 walls during the months of June and July. It makes its burrows 

 in walls and high banks, while many other allied species form 

 their nests in the hollow stems of brambles. 



Family 5, Masaridce. — This family contains the great bulk of 

 the soHtary wasps, which, however, are principally inhabitants of 

 warm climates. 



The MasaridcB are a small group of black-yellow belted wasps, 

 which are found in the south of Europe, but not in Britain, two of 

 the commonest species being Cdonites apiformis and Ccramius 

 fo7iscolombi. 



Section 3. — Fos sores. 

 Family 6, Philanthidce. — Most of the species belonging to this 



Fig. 20. — Cerceris Capito. 



family are black with yellow spots and bands, and most of them 

 are inhabitants of the warmer parts of the earth. Some of the 

 species provision their nests with beetles and grasshoppers, while 



