THE SOLITARY WASPS 27 



solitary wasps are subject to the attacks of 

 cuckoos belonging to the jewel fly or Chrysis tribe ; 

 these behave differently from those belonging 

 to the aculeate groups, as their larvae do not 

 eat the food laid up for the wasp, but wait 

 till the wasp larva has finished feeding up, and 

 then devour it. Unlike as these cuckoos are 

 to their hosts in their brilliant metallic coloration, 

 etc., they have structural characters curiously 

 like theirs, so that even here a common parentage 

 in bygone generations may be reasonably sus- 

 pected. At present, however, they are placed, 

 except by a few systematists, in quite distinct 

 families of the Hymenoptera. 



In general form these solitary wasps resemble 

 the fossors more than the bees ; they have mostly 

 short tongues (I think all our British ones have), 

 and their hairs are simple or more or less spirally 

 twisted. 



