106 BRITISH APHIDES. 



hnndreds congregated on a single twig of the peach 

 tree in August. The apterous form occurs as early as 

 April. Sometimes the swarms disappear for two or 

 three months, and again appear in larger numbers late 

 in the autumn.* These Aphides are much resorted to 

 by ants. 



Koch found his ApMs iJersiccB feeding on the 

 sloe, and Mr. Walker considered that it migrated like 

 the hop Aphis. I have taken the winged form on the 

 tobacco plant, but the occurrence of winged females on 

 any plant does not prove that it was bred there. A. 

 persicce of Fonsc. may be easily distinguished from 

 Myzus, by the absence of frontal tubercles and the 

 shortness of its nectaries. 



Passerini identifies the Puceron de peclies of Morren 

 with Aphis rapcB of Curtis, and proposes to call it 

 RhopaJosiplmm p>ersicce. This would still more com- 

 plicate the synonomy, besides which the original name 

 dianthi should be retained. The general form of Aphis 

 amygdali is exceedingly bug-like. 



It may be mentioned that Hyalopterus pruni also 

 attacks the peach-tree. 



Parasite on Aphis amygdali. Plate LXXIII, fig. 6. 



Late in October I bred from the larvas of this Aphis 

 several small insects, which Mr. Walker concurred with 

 me in calling Gijni'indcB. I have been unable, even by 

 the aid of others, to identify the species, and therefore 

 provisionally I name it Cynips atricejjs, and thus 

 describe it : 



Body wholly shining black. Antennae pilose, with 

 fourteen joints, each after the third slightly increasing 

 in size, the last apical joint being the largest. Thorax 

 robust. Abdomen semi-globose, the last ring furnished 



* Examples of migration from one tree to another of a different 

 species are multiplying. Liclitenstein has lately noticed such a habit 

 in some Pemphiginse. 



