268 Lawson on Aphis Avencd. 



but which are now explained by corresponding peculiarities in 

 some other groups. A full history of the enquiries of Bonnet 

 and others was given by Mr. Hardy, in a series of papers published 

 some years ago in the Scottish Gardener. 



Prof. Huxley's important papers " On the Agamic Reproduc- 

 tion and Morphology of Aphis '* will be found in the third part of 

 the 22d volume of the Transactions of the Linnean Society(1858). 



The following is a detailed description of the wheat or grain 

 aphis : 



Aphis Aven^. — Plump, pale reddish to brown or apple-green 

 (usually pale-red but very various as regards colour), with black- 

 ish legs and feelers, appears late in summer in colonies, on flow- 

 ering panicles of grasses and cereal grains, becoming winged and 

 leaving the ears, as the season advances and the grain ripens. 



Viviparous Wingless Female. — Body, medium sized, j^^h. to 

 Y^L^th of an inch in length, oval-oblong, convex with a rim on 

 each side, more or less glossy, especially when mature, varying in 

 colour from pale apple-yellow to deep reddish yellow or reddish 

 brown when young, becoming darker when old ; often of a deep 

 brick-red or chestnut brown, especially on the dorsal surface of 

 the abdomen and other exposed parts, rarely the whole body is 

 of a dull glaucous green, sparsely covered with scattered hairs. 

 The feelers are black, rather more than half the length of the 

 body, rough throughout with bristly hairs, the two basal joints 

 short and thick, especially the first, the terminal one remarkably 

 long and slender, transversely notched throughout its whole 

 length, the intermediate ones four or five times as long as broad 

 (only six joints are developed). The eyes are dark, the rostrum 

 quarter the length of the body, of a yellowish or tawny hue, the 

 terminal joint black, the nectaries almost black. The legs are 

 tawny, the knees, the feet, and the tips of the shanks black, all 

 rather closely covered with bristly hair. 



Viviparous Winged Female. — Dark brown, sometimes almost 

 black, feelers longer than the body, hairy, dorsal processes of the 

 abdomen (" nectaries") about a fifth the length of the body ; legs 

 dark, the knees, feet, <fec., black, hairy ; wings ample, colourless, 

 longer than the body. Size of body \ inch ; of the wings -j inch, 

 Mr. Walker has been very successful in distinguishing aphides 

 by the venation of the wings. I therefore give in his words the 

 description of the wing veins: — " Distance between the first and 

 second veins at the base less than half that between them at the 



