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



297. 25 ; Gmelin, Syst. Nat. i. 2206 ; Rcauiii. Ins. iii. t. 22. f. 2 ; 

 Schrank, Fauna Boica, ii. 1. 110; Geoff. Ins. i.496. 7 ; DeGeer, 

 Ins. iii. 45. 3. f. 27, 28 ; Kalt. Mon. Pflan. i. 144. 118. 



Aphis nigritarsis, Heyden, Mus. Senkenberg. ii. Heft 3. p. 299; 

 Kalt. Mon. Pflan. i. 135. 103. 



Aphis punctipennis ?, Zetterstedt, Faun. Lapp. i. 559. 4 ; Ins. 

 Lapp. i. 2. 311. 7. 



This large and handsome species may often be seen flying 

 about birch-trees during the summer and the autumn ; it has some 

 resemblance to A. Platanoidis, but the successive generations are 

 more variable both in structure and in colour, and local differ- 

 ences also occur. Zetterstedt's A. punctipennis inhabits the birch 

 and the alder, and has been found in Lapland and in Greenland. 



The viviparous winged female. This appears before the middle 

 of April on the leaves of the white birch-tree, Betula alba ; while 

 a pupa it is narrow, long, linear and bristly, and of a bright grass- 

 green colour : the feelers are not more than half the length of the 

 body : the legs and the rudimentary wings are pale green, and 

 there is a spot of the same colour at the base of each nectary. The 

 wings are unfolded before the end of April, and the insect is then 

 of a grass- green colour, and often quite covered with a white 

 bloom : the crown of the head bears two impressions, and in front 

 it is rather narrow and nearly straight, but there is a slight pro- 

 tuberance at the inner base of each feeler : the feelers are black 

 and shorter than the body ; the fourth joint is much shorter than 

 the third, but much longer than the fifth, whose tip is very slightly 

 dilated ; the sixth is also slightly dilated at the tip, and is nearly 

 half the length of the fifth ; the seventh is rather more than half 

 the length of the sixth : the eyes are dark red : the mouth is black, 

 green towards the base, and hardly reaches the middle hips : the 

 chest has a slight tawny tinge ; its disc is nearly black, and it has 

 a dark spot on each side : the breast is black : there are six rows 

 of black tubercles along the back of the abdomen : the nectaries 

 have black tips, and are less than one-twentieth of the length of 

 the body : the legs are dull green, rather long and stout ; the 

 thighs are somewhat paler towards the base ; the feet and the 

 tips of the shanks are brown : the wings are colourless, and longer 

 than the body ; the wing-ribs and the rib-veins are pale yellow j 

 the wing-brands are rather darker ; the veins are brown, and their 

 tips are slightly clouded. 



1st variety. The pupa. Bluish green. 



2nd variety. The pupa. Yellowish green, especially towards 

 the head. 



3rd variety. The pupa. Dark green. 



4th variety. The pupa. Blackish. 



5th variety. The disc of the head is nearly black : the legs 



