254 Mr. F. Walker's Descriptions of Aphides. 



of the sycamore. The eggs are spindle-shaped, and very large in 

 proportion to the size of the mother ; when newly laid they are 

 pale, but they soon become black and shining, and have much 

 resemblance in size, shape and colour to the eggs of most other 

 species of Aphis. I have not seen more than twelve eggs in the 

 body of a single insect, and the number is usually much less ; the 

 egg lies lengthwise along the body, and by preserving the Aphides 

 in Canada balsam the process of its formation is seen, and it may 

 be ascertained to be homogeneous, and not a mere envelope for the 

 young Aphis, as some authors have conjectured. An egg some- 

 times occurs in the fore-chest, but its presence there is probably 

 accidental. 



The winged male. Unfolds its wings in the beginning of Oc- 

 tober ; it is darker than the winged female, and has more nume- 

 rous marks on the chest and on the abdomen, and its wing-brands 

 are also of a darker colour. It is brownish yellow : the head, the 

 disc of the chest, and that of the breast are brown : the head is a 

 little broader than the chest : the abdomen is brown and linear, and 

 has a broad pearly whitish green stripe on each side ; the feelers 

 are thick towards the base, and longer than the body : the nec- 

 taries are dull pale yellow, brown at the base, and as long as one- 

 fourth of the body : the thighs except the base, and especially the 

 hind- thighs, are somewhat darker than the shanks. In the fore- 

 wing of one fly the lower vein of the first fork, instead of pro- 

 ceeding to the hind-border of the wing, curves backwards and 

 joins the second vein at a short distance from its tip. It pairs 

 with the wingless female from the middle till the end of October. 



1st variety. Black in such parts where this sex is usually 

 brown. 



In this species, as in other Aphides, the union of the branch- 

 veins with the rib-vein is usually more or less imperfect, and this 

 variableness occurs even in the opposite wings of one fly, but the 

 junction is in some cases fully effected. The seventh joint of the 

 feelers has occasionally but little more than half its usual length. 



Length of the body 2 lines ; of the wings 4 lines. 



2. Aphis Acerina, n. s. 



I observed this insect near London from the beginning of July 

 till the end of October 1847, feeding on the leaves of two young 

 sycamore-trees {Acer Pseudo-platanus) that were about five feet 

 high, and were situate a mile apart from each other, one in a 

 garden, the other in a wood. It is a very lively, active and 

 elegant species. 



The viviparous winged female. Its body is of a bright lemon- 

 colour : the feelers are yellow, and very much longer than the 

 body ; the tips of their joints are brown ; the third joint is very 



