152 BEITISH APHIDES. 



The particular genus Apliidius, was devised by Mr. 

 Haliday, who grouped the parasitic species then known 

 under the sub-family Ichneumonides adsciti of Nees ab 

 Esenbeck. 



The larvge are footless grubs, which develope from 

 eggs laid by the winged females (generally singly, but 

 sometimes five or more) within the bodies of the 

 Aphides. These grubs live on the food assimilated by- 

 the Aphides, and do not, until at the last moment, 

 attack their vital organs. The pupas undergo their 

 metamorphosis in silken cocoons ; or, rather, the dry 

 skins of their victims form the necessary cells, which 

 are sparsely lined with silk. The number of antennal 

 joints of the perfect insect varies from above sixteen 

 even to sixty. The wings are more elaborately 

 veined than in the Cynipid^, and yet more markedly 

 so than in the Chalcidiee. 



A few insects of this group may be mentioned under 

 the following genera, of which the genus Aphidius 

 may be recognised by the comparative simplicity of the 

 wing-veining : 



Aphidius rosea (Hal.), a common species which attacks 

 SipJionophora rosce. In the middle of June, I watched 

 for more than a quarter of an hour a sprig of rose 

 bush incrusted with Aphides. Two individuals of the 

 above Aphidius were seated on the backs of two 

 Aphides. They seemed to be pleasurably excited by 

 the wriggles and contortions made by their victims 

 in their attempts to throw them off", for they remained 

 fixed for five or more minutes before they inserted 

 their ovipositors by a sort of thrust. After this act, 

 they took flight in pursuit of other game. This 

 Aphidius had long, straight, unflagellate antennas, com- 

 posed of seventeen almost equal joints. 



Aphidius cancellatus has a similar parasitic habit on 

 several Aphides. It is figured in Vol. I, Plate IV, fig. 4. 



Aphidius avence (Hal.) is described in Curtis' ' Farm 

 Insects,' part i, fig. 12, p. 303. It is parasitic on 

 Siphonophora granaricB. 



