NOTES ON THE GENUS APHIS. 405 



with reason and analogy, the question, as I before hinted, must 

 be left, sub judice, until future facts and observations shall 

 discover the truth. 



Guy's Hospital, Ulh month, 1835. 



Art. XXXVI. — Notes on the Genus Aphis. By Francis 

 Walker. 



Latreille separated the genus Aphis, Linn, into three 

 divisions, which he thus characterised : — 



I. — Abdomen bicorniculatum. Antennae setaceag, elongatae. 

 II. — Abdomen bituberculatum. Antennae saepe filiformes. 

 III. — Abdomen cornieulis tuberculis que nullis. Antennas filiformes, 

 breves ; corpus in multis tomentosum ; insecta ssepius in gallis 

 improprie dictis degentia. 



Lachnus, Illiger, comprises the second division, and the 

 genera Myzoxyle, Blot, and Phylloxera, Fonscolombe, pro- 

 bably belong to the third, which Burraeister describes as 

 Chermes, Linn. 



Aphis.— This genus is still very extensive, and in some 

 instances includes two distinct species, that feed on the same 

 plant, so that a subdivision is required to avoid confusion, for 

 most species are as yet only described by the names of the 

 plants which they infest. 



I. Horns of the abdomen very short, body generally small 

 and narrow. Among the species of this division are : — 



1. Aphis of the lime. — The prettiest species of the genus, is 

 found in all stages of growth under the leaves of lime trees, 

 during the summer and autumn. When full grown it is bright 

 yellow or green, the scutel and sides of the head and thorax are 

 black, and two rows of black spots extend along the sides of 

 the abdomen ; the antennae have alternate rings of yellow and 

 black ; the hind thighs are black ; the wings white, spotted 

 with brown at the tips of the nervures, the costa also brown. 

 The young ones are entirely pale green and semi-pellucid. 



2. Aphis of the oak. — It is a small delicate green species, 

 having sometimes, but very rarely, a bright yellow hue; the 



