Mr. F. Walker\s Descriptions of k^\i\A{t'&. 453 



as almost to form a tubercle on each segment : the fore-chest is 

 large : the middle chest is rather shorter : the hind-chest and the 

 following segments are much shorter and of nearly equal size : 

 the feelers are slender, almost filiform, pale green at the base, 

 brown at the tips, and less than one-third of the length of the 

 body : the eyes are brown ; the mouth is dull green : the nectaries 

 are yellow, and about one-twentieth of the length of the body : 

 the legs are dull green, long and stout ; the feet are brown. Id 

 the middle of April on the shoots of the willow. 



1st variety. Dull olive-green, varied with brown. 



The viviparous winged female. The wings of this fly are un- 

 folded before the middle of may : it is metallic black, and slightly 

 covered with gray powder : the fore-breast and the underside of 

 the abdomen are grayish green, and the back of the latter has 

 alternate bands of black and gray : the feelers are black, slightly 

 setaceous, and hardly half the length of the body ; the fourth 

 joint is much shorter than the third ; the fifth is a little shorter 

 than the fourth ; the sixth is shorter than the fifth ; the seventh 

 is a little longer than the sixth : the mouth is dull green with a 

 darker tip, and reaches a little beyond the base of the hind-legs : 

 the eyes are black : the nectaries are orange and extremely short : 

 the legs are black, long and stout ; the thighs towards the base, 

 and the shanks except their tips are dark red : the wings are 

 colourless, and longer than the body ; the wing-ribs are pale 

 yellow ; the wing-brands are long, and dull buff; the veins are 

 brown ; the rib- vein does not widen into the brand, but passes 

 along its hind-border ; the first and the second veins are nearly 

 straight ; the third is obsolete at its soui'ce, and is inclined in- 

 wards, and forms two very slight obtuse angles where it throws 

 off its forks ; the first fork begins soon after one-third, the second 

 soon after two-thirds of the length of the wing : the legs are 

 rather stout, and long, and hairy. 



Length of the body 2 lines ; of the wings 3^ lines. 



Thirteenth Group. 

 Containing one species which seems to be always wingless. 



25. Aphis Salicivora, n. s. 



The viviparous wingless female. The body is oval, flat, hairy, 

 and yellow : the hairs on the sides of the body are very long : the 

 front is hairy and slightly convex, and has no tubercles : the 

 feelers are slender, setaceous, and nearly as long as the body ; the 

 fourth joint is much shorter than the third ; the fifth is fully as 

 long as the fourth ; the sixth is shorter than the fifth, and in- 

 creases in breadth from the base to the tip ; the seventh is much 



