HYMENOPTERA 



CHAP. 



formed by the pronotum on the dorsal part (Fig. 26). By a 

 glance at this part a Diplopterous Insect can always be readily 

 distinguished. 



Three families are at present distingviished in the Diploptera, 

 viz. Eumenidae, Vespidae and Masaridae. ^\'e anticipate that 

 Eumenidae and Vespidae will ultimately be found to constitute 

 but one family. 



Fam. 1. Eumenidae — Solitary True Wasps. 



Claws of the feet toothed 07' hificl ; middle tibiae loith only one 

 sjnir at tip. Social assemllages are not formed, and there is 

 no worker-caste, the duties of nest-construction, etc., being 

 'performed solely by the female. 



The Eumenidae, or solitary wasps, are very little noticed by 

 the ordinary observer, but they are nevertheless more numerous 



than the social Vespidae, about 800 

 species being known. In Britain we 

 have sixteen species of the solitary, as 

 against seven of the social wasps. 

 The Eumenidae exhibit a considerable 

 diversity in form and structure ; some 

 of them have the pedicel at the base 

 of the abdomen very elongate, while 

 in others this is so short as to be 

 imperceptible in the ordinary position 

 of the body. A repetition of similar 

 differences of form occurs in the social 

 _ „, ^ ^ . wasps, so that notwithstanding the 



-TIG. 27. — Eumenes flcmopicta '}. -..^ . ° 



Burma. The wings on the leit Qinerence in habits there seems to be 

 show fokuf ''"' °^ ^'^°''' *° ^° satisfactory way of distinguishing 

 the members of the two families ex- 

 cept by the structure of the claws and tibial spurs. 



Pabre has sketched the habits of a species of Eumenes, 

 probably E. pomiformis. This Eumenes constructs with clay a 

 small vase-like earthenware vessel, in the walls of which small 

 stones are embedded (Hke Fig. 28, B). This it fills with food 

 for the young. The food consists of caterpillars to the number 

 of fourteen or sixteen for each nest. These caterpillars are 

 believed to be stung by the parent-wasp (as is the case in the 



