116 
BRITISH APHIDllS. 
pale brown or rusty yellow. Eyes red. Thorax brown, 
with oblong and darker coloured thoracic lobes. Scu- 
tellum brown. Abdomen ovate, broad, shining green. 
Dorsum domed, with four well-marked black dots. 
Lateral carinations obvious, each showing three large 
black spots in the folds. Cornicles black, long, 
straight, thickest at their bases. Antennse longer 
than the body. Frontal tubercles not largely deve- 
loped. The first joint thick, and three times the 
length of the second. Legs ochreous with black 
genua and tarsi. Cauda yellow, ensiform, and hairy. 
Rostrum reaches to the second coxse. Wings ample, 
with green insertions and dark brown veins ; cubitus 
and stigma pale brown. 
This Aphis infests many gramineous plants, but 
chiefly the wheat {Triticum), Schrank found it on the 
oat {Avena)^ and Koch observed it sparsely scattered on 
the barley (Rordeum). Also he noticed that the larva 
affects the upper sides of the blade, whilst the winged 
female attacks the ear. The food plants enumerated 
by Kaltenbach are, Secale cereale^ Triticum sativum, 
Avena fatua, Rordeum murinum, Bromus mollis, Dac- 
tylis glomerata, Rolcus, Boa, and other grasses. 
Walker adds to these Glyceria fluitans, and Polygonum 
^ersicarice. Sometimes the flower heads of grasses 
hang down by the weight of aphides upon them. 
Markwick as early as the year 1797 noticed the 
attacks of Aphides on wheat crops. Fabricius gave no 
description of his Aphis avence ; but Kirby, in his 
interesting paper, read before the Linnean Society, 
described probably the same insect under a different 
name. This name has thus priority over those given 
by later continental authors, and so I adopt it. 
Early in the year the young aphides absorb sap 
from the blade close to the stem, but later they attack 
the ears in vast numbers, inserting their rostra close 
to the junctures of the grains with the stalk. Some- 
times as many Aphides are present as there are grains 
in the ears. 
