Mr. F. Walker's Descriptions 0/ Aphides. 43 



VIII. — Descriptions 0/ Aphides. By Francis Walker, F.L.S. 



[Continued from vol. ii. p. 431.] 



56. Aphis dirhoda, 11. s. 

 This species feeds on the rose with Aphis Rosa, and is some- 

 times far more numerous than that species in the spring and in 

 the autumn, but its appearance is less regular ; it frequents various 

 species of rose both wild and cultivated, such as Rosa centifolia, 

 R. canina, R. eglanteria ; and in the summer it migrates to dif- 

 ferent species of corn and of grass {Secale, Triticum, Avena, Ho?-- 

 deum, Bromus, Dactylis, Holcus, and Poa), and it fixes itself on 

 the blades of these plants, whereas^. Avenae prefers the flowers. 

 Aphidius Avena, an Allotria, Asaphes anea, and Megaspilus Car- 

 penteri, are its parasites, and these will be more particularly 

 noticed in another part of these descriptions. 



The viviparous wingless female. This sometimes rests through 

 a severe winter under the rose-leaves without being injured, and 

 begins to multiply very early in the spring : it is oval, and pale 

 greenish yellow : the feelers have pale brown tips, and are about 

 one-fourth of the length of the body : the eyes are dark red : the 

 mouth and the nectaries are pale yellow with brown tips, and 

 the latter are about one-sixth of the length of the body : the tip 

 of the abdomen is brown : the legs are shorter and more slender 

 than those of Aphis Rosa, and the feet are pale brown : it is also 

 distinguished from that species by its paler colom-, its shorter 

 feelers, and its larger body ; the two kinds may often be seen 

 together on one rose-twig, each surrounded by its respective little 

 ones. 



The front is prominent in the middle between the eyes : the 

 tubercles on w^hich the feelers are seated are rather less developed 

 than those of the preceding species ; the fourth joint of the feelers 

 is much shorter than the third; the fifth is shorter than the 

 fourth ; the sixth is not half the length of the fifth ; the seventh 

 is nearly as long as the third. 



The viviparous winged female. While a pupa it much resembles 

 the wingless female in colour : its wings are unfolded in April or 

 May, and then it is pale green : the chest is bufi" ; its lobes are 

 pale brown : the feelers are brown, green at the base, and much 

 shorter than the body ; the fourth joint is shorter than the third, 

 and the fifth is shorter than the fourth ; the sixth is nearly half 

 the length of the fifth ; the seventh is a little shorter than the 

 third : the eyes are dark brown : the mouth has a brown tip : the 

 nectaries are about one-sixth of the length of the body : the legs 

 arc pale yellowish green and rather long ; the feet and the tips of 

 the thighs and of the shanks are brown : the wings are colourless. 



