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



rather opake : the young ones are sometimes near thirty in num- 

 ber, and like the mother Aphis are covered with a glutinous mat- 

 ter, which by the application of Canada balsam assumes a fine rich 

 red hue : the insects infested by parasitic grubs do not so much 

 abound with this coloured matter, but contain a white fluid, which 

 also occurs, but in a smaller quantity, in those that are free from 

 the internal devourers : these grubs are 1 line or more in length, 

 white, slightly curved, and being inclosed in Canada balsam and 

 thereby rendered transparent, they appear to be filled with the 

 brown oak sap received through the medium of their prey. 



44. Aphis agilis. 



Lachnus agilis, Kalt. Mon. Pflan. i. 161. 11. 



The viviparous wingless female. The body is spindle-shaped, 

 grass-green, long and narrow, with three rows of black spots 

 along the back : the front, the feelers, and the shanks are bristly : 

 the front of the head is slightly notched : the feelers are filiform, 

 pale green with brown tips, and much less than half the length 

 of the body ; the fourth joint is rather more than half the length 

 of the third ; the fifth is as long as the fourth ; the sixth is very 

 much shorter than the fifth ; the seventh is extremely short, and 

 almost obsolete : the eyes are dark brown : the mouth is pale 

 green with a brown tip, and reaches to the hind-hips : the sides 

 of the fore-chest are straight : the nectaries do not rise above the 

 surface of the body : the legs are dull green, stout, long and 

 bristly ; the hind-legs are very much longer than the fore-legs ; 

 the knees and the feet are brown; the joints of the feet are 

 unusually long, and the second joint is curved ; the hind-shanks 

 are very bristly. It runs very fast. 



1st variety. The body linear. 



2nd variety. The feelers only one-third of the length of the 

 body. 



3rd variety. The fore-part of the body is tinged with yellow, 

 and Ihere are four rows of black dots along the abdomen : the 

 feelers are about half the length of the body. 



The viviparous winged female. This insect acquires wings in 

 the beginning of June : it is green, slightly covered with white 

 powder, and in shape resembles the wingless female : the disc 

 of the chest and that of the breast are pale reddish brown : 

 the feelers are brown, pale yellow at the base, and a little more 

 or less than half the length of the body : the eyes are dark 

 brown : the mouth is pale yellow ; its tip is brown : the legs are- 

 long and pale yellow ; the knees, the feet, and the tips of the 

 shanks are brown : the wings are transparent, narrow, and a lit- 

 tle longer than the body ; the wing-ribs are pale green ; the wing- 

 brands and the veins are pale brown ; the rib -vein widens into 



