128 



HYMENOPTERA 



CHAP. 



FIG. 50. Mimesa bicolor f, 

 Britain. 



information exists as to their liabits ; but Verhoeff states that 



the species of Pscn like mem- 

 bers of the Pemphredoninae 

 do not form cocoons. 



The Pemphredonine subdivi- 

 sion includes numerous small and 

 obscure Insects found chiefly in 

 Europe and North America (Fig. 

 51, P. lugubris)', they resemble 

 the smaller black species of Cra- 

 bronides, and are distinguished 

 from them chiefly by the exist- 

 ence of at least two complete, 

 submarginal cells on the an- 

 terior wing instead of one. 

 The species of Passaloecus live in the burrows that they form 



in the stems of plants ; Pemphredon lugubris frequents the decayed 



wood of the beech. The larva and pupa of the latter have been 



described by Verhoeff; no 



cocoon is formed for the 



metamorphosis. Both these 



genera provision their nests 



with Aphidae. This 



also the case with Stt 



pendulus, but the burrows 



of this species form a com- 



plex system of diverticula 



proceeding from an irregu- 



lar main channel formed in 



the pithy stems of bushes. 



Cemonus unicolor, according to Giraud, forms its burrows in 



bramble - stems, but it also takes advantage, for the purposes 



of nidification, of the abandoned galls of Ct/nij>n, and also ol 



a peculiar swelling formed by a fly Llpm-n lucens on the 



common reed, Arundo p/i /</>/ mites. This species also makes 



use of Aphidae, and Verhoeff states that it has only an imperfect 



instinct as to the amount of iood it stores. 



Sub-Fam. 10. Crabronides --Pi'onoitun short, front u-rmj u-iih 

 one co////>/i fr submarginal and two discoidal cell* : hind body 



s 



FIG. 51. Pemphredon luyitbris 9. Britain. 



