164 BRITISH APHIDES. 



exclusive as to the choice of plants for its nidification, 

 mentioning, amongst others, the rosej the bramble, the 

 elder, and Eryngium camj^estre. The fact is curious 

 also that it often inhabits the galls forsaken by Gyni])s 

 Kollari and those made by Dipterous flies. He mentions 

 three parasites which attack the Pemphredon in its 

 galleries.* 



Fsen atratus. — Kennedy observed this insect 

 " making its cells in the straws of thatch, providing 

 them with Aphides. As many as one hundred were 

 found in some of them. The egg of this insect is 

 white and semi-transparent, and is attached to the 

 abdomen of an Aphis at the bottom of the cell."t 

 He remarks that the partitions of the cells appear to 

 be made of the cemented scrapings of the inside of the 

 straw. The images appeared in July, by thousands 

 about the thatch. By the kindness of Sir Sidney 

 Smith Saunders I am enabled to figure this insect 

 from his cabinet, and also to represent the mode in 

 which a long series of cells, have been constructed in 

 a bramble stem. There can be little doubt that these 

 cells are provisioned by the mother with Aphides, just 

 as in other like cases we find them stored in straws. 



Giraud, describing the cells made by Psen, says, 

 " une cloison mince, dure, lisse, un pen bombee, resem- 

 blant a une rondelle de parchemin formait la separa- 

 tion des cellules."! Further, he says the genus Psen, 

 like the genus Mimesa, which has been separated from 

 it, has been regarded by many authors as parasitic ; but 

 this opinion has been combated by the observations 

 of Westwood, Kennedy, Schenck, and by others. 

 Giraud doubts not that Psen concolor provisions its 

 cells with Psyllidge, and he points out the curious 

 fact that all those seen were nymphs and not larvse, 

 for they all had thoracic scales, representing the rudi- 

 mentary wings. "Amongst the numerous kinds which 



* Giraud, 471. 

 t Kennedy, p. 17. 

 X Giraud, p. 470. 



