130 



FRED. V. THEOBALD. 



yellow to yellowish green, mainly the former ; that is, the same colour as 

 Aphis nerii. The antennae of the alate female are black, and in the apterous female 

 the third and fourth segments are pale, or the base only of each segment is pale ; the 

 cornicles are jet-black, as are also the cauda and anal plate ; the hind legs are all 

 dark, but the fore and mid legs have paler bases to the femora and most of the tibiae 

 pale. In the form on Salix the colour is the same, but in the apterous female aU the 

 legs are dark, whilst in the alate female only the hind legs are all dark. In this form 

 (nigripes, Theo.), the antennae of the apterous female may be all dark or pale at the 

 base of the third and fourth segments. Both forms have a large dark patch at the 

 base of the cornicles in alate and apterous insects. The third segment of the antennae 

 in the alate female has from 6 to 1 1 sensoria and 0-1 on the fourth segment in specimens 

 from Asclepiads ; but in the Salix specimens the third has from 8 to 12 sensoria (fig. 22). 

 The cauda has six to seven pairs of hairs on each side in both winged and wingless insects. 

 On the pronotum is a blunt papiUa on each side, also one between the cornicles and 



a 



pffl.v!, >:":';','.'M '''/?rf 



B 



r 3r>'.v,',w 



■JUUM 



o'g>i»e»' 



TT- 



-r— ^ A {V '■''"','" "','(',"(^11 



'■"''^'■'I'lf'l L 



— I_l 1 iP>oaiaaftMift.ai^i'wM_ l|',V.' .'{'!.".' .''"f'^,'.'y'.' 



Fig. 22. A, Myzus nerii, Schr., alate $ ; B, If. aselepiadis. Pass. ; 

 C, Jf. aschpiadis var. nigripes, Theo. ; (a), antennal segments 3 and 4 ; 



(6), cornicle ; (c), cauda. 



cauda. The yeUow alate female has a black head and thoracic lobes, and the 

 abdomen shows two darkened areas with a median paler division ; the venter is 

 yellow, except for the black mesosternal plate and the black coxae. The wings are 

 sHghtly tinged with pale yellowish-brown ; veins and stigma brown. On the 

 abdomen there are four pairs of minute black specks and three dusky pairs of lateral 

 spots. The apterous female has two black spots on the pronotum, a hne of small 

 black spots (seven in number) on each side, a black hne before and behind the 

 pronotum, and one uniting the first pair of small lateral spots. The antennae of 

 the apterous female have the fifth segment shorter than the fourth. 



In A. nerii, Boyer, the colour is the same and the insect has the same general 

 appearance ; but in the alate female the black cornicles are thinner and more uniform 

 in size, the cauda has only 3-4 pairs of lateral hairs, and in both alate and apterous 

 females I can see no trace of the black spots at the base of the cornicles ; moreover, 

 in the apterous female the fifth antennal segment is as long as the fourth, and the 

 black cauda has only 3 to 4 pairs of lateral hairs. 



It thus seems clear that Passerini was quite correct in placing the yellow Asclepiad 

 aphis as a distinct species from that of the oleander {Nerium oleander). The nymphs 

 in both species have black wing-pads and black lateral specks, as in the apterous 

 females. 



