CHAPTER IJ 



HYMENOPTEEA ACULEATA COXTIXCJiD DIVISION II. DIPLOPTERA 



OR M'ASPS EUMENIDAE, SOLITARY TRUE WASPS VESPIDAE, 



SOCIAL WASPS MASARIDAE 



Division II. Diploptera — Wasps. 



Anterior wings longitudinally plicate in repose; the pronotum 

 extending haclc, so as to form 

 on each side an angle reposing 

 on the tegula ; the hasal seg- 

 meyits of the hind hody not 

 hectring nodes or scales ; the 

 hind tarsi formed for simple 

 ivcdking. The species either 

 solitary or social in their ^ 



hahit'i- '^ome eri'itinn in fhree ^'«- 26.— Upper aspect of pronotum 

 naollS, some existing %n tlliee and mesonotiim of a wasp, £«me- 



forms, mcdes, females, and "«« coarctata. «, Angle of prono- 



^^ _ turn ; &, tegula ; c, base of -wing ; 



WOrlCerS. ^_ mesonotum. 



This division of Hymenoptera includes the true wasps, but not 

 the fossorial wasps. The name applied to it has been suggested 

 by the fact that the front wings become doubled in the long direc- 

 tion when at rest, so as to make them appear narrower than in 

 most other Aculeata (Fig. 27). This character is unimportant 

 in function so far as we know,^ and it is not quite constant in 

 the division, since some of the Masaridae do not exhibit it. The 

 character reappears outside the Diploptera in the genus Leucospis 

 — a member of the Chalcididae in the parasitic series of Hymen- 

 optera — the species of which greatly resemble wasps in coloration. 

 A better character is that furnished by the well-marked angle, 



' Janet lias suggested that the folding is done to keep the delicate hind-margins 

 of the wings from being frayed. 



