36 BEES AXD WASPS [CH. 



and may often be seen visiting various umbelliferous 

 plants and others whose nectar is placed within 

 reach of their short tongues. 



CHAPTER IV 



DIPLOPTERA (DOUBLE-WINGED WASPS) 



As already stated the members of this, the highest 

 of the wasp families, are characterised by the longi- 

 tudinal fold into which the front wing is thrown when 

 at rest. Of the two sections comprising the family 

 the Eumenidae or mud-wasps are solitary, while the 

 Vespidae or social-wasps form the great communities 

 with which every one is more or less acquainted. 

 There are also structural differences by which mem- 

 bers of the two sections can be distinguished : the 

 solitary forms have a longitudinal furrow running 

 along the outer face of their mandibles, and have a 

 small " tooth " near the apex of their claws ; whereas 

 the mandibles of the social-wasps have no such 

 furrow, nor are their claws toothed. We have only 

 two genera of mud- wasps represented in this country, 

 viz. Eumenes and Odynerm. Both are narrow bodied, 

 and yellow and black in colour. The former is char- 

 acterised by an elongated " waist." Its sole British 

 representative, E. coarctata, makes little globular 



