150 BEITISH APHIDES. 



tant Aphidivorous insects under the head of fossorial 

 CrabronidjB. 



The Cynipid^. 



Though as a general rule these insects are gall-feed- 

 ers, several forms are known to be parasitic. Such 

 habits, not in accordance with the usual economy of 

 the group may warn classifiers not to trust exclu- 

 sively either to unique modes of life or structural 

 peculiarities, in assigning the natural affinities of any 

 animal. 



The " Cinips de I'lchneumon de pucerons" of 

 Geoffroy, Westwood has shown, belongs to the Chalci- 

 dia3 ; but the latter author, in June 1833, bred a true 

 Cynips from the larva of Ai)Ms rosce, which, he says, is 

 specifically distinct from Cynips erythrocephala, of 

 Jurine, which, Haliday says, likewise infests the rose 

 Aphis.* 



Curtis remarks also that Cynips fulviceps and 

 another species destroy the Aphides of the willow and 

 the parsnip. t 



M. Goureau obtained a black Cynips with a red head 

 and rufous legs from Aphis rosce, which, he says is 

 distinct from C. fulviceps and C. erytlirocephala. The 

 same insect also is parasitic on one of the plum Aphides. 

 In addition to those drawn on Plate LXXIII, fig. 6, of 

 this Monograph, may be seen a black Cynips, which I 

 bred from Fonscolombe's peach Aphis, Aphis amygdali. 

 On account of its black head and legs, it does not 

 appear to be identical with either of the above noticed 

 Cynipidge. 



Singularly, where there are specific differences, it may 

 happen that foes become friends. This may be in- 

 stanced by the fact that some Aphides, like Phylloxera 

 querctis (punctata ?),OGGasioiiBl\j take up their abode in 

 the chambers of galls, the produce of their enemies 

 the Cynipidse. It is not improbable that the accumu- 



* Westwood's ' Intro. Mod. Class.,' vol. ii, p. 132. 

 t ' Eut. Mag.,' ii, p. 102. 



