VARIATIONS IN TRIFIDAPHIS RADICICOLA 285 



First and Second Obliques or Discoidals. 



A. Arising from an extension of the pigment of the subcostal, but 



not from same point. Normally curved. 



B. Arise from pigment nearer the same point than in A. 



C. Arise from a prominent extension of the pigment near the same 



point. 



D. Nearly the same as A. 



E. Arising from no extension of the pigment from the same point. 



F. Arising from no extension of the pigment from different points. 



G. Nearly same as in B. 



H. Nearly same as in F, only veins are straighter. 

 I. Same as in B and G. 



J. The two are united for quite a distance from the pigment as 

 one vein. They then fork and diverge to the margin. The 

 other wing of the insect to which this belonged was normal 

 as I. 

 Third Oblique or Discoidal. 



A. Slightly curved and normal in this species. 



B. Very short remnant near the stigma. A rare occurrence. 



C. Norma! vein. 



D. Normal vein. 



E. Normal vein. 



F. Normal vein, but interior tip rather low. 



G. Normal vein. 



H. Forked, so as to make the first and second forks of a normal 

 aphid wing. The other wing of the individual having this 

 wing, was normal as I. 

 I. Normal vein. 



J. Normal vein, but crowded, probably due to abortive growth. 

 It might be said that a great many of the individuals are very small 

 and abortive, but the wings, though small, are usually normally developed. 

 Of the drawings presented these were not included except the one marked J. 

 I'ariafions in the Antennae. (Fig. 110, K, L, M.) — There is a frequent 

 variation in regard to the number of articles — the normal being six and 

 others five. The one described, as referred to above, had only five articles. 

 This change is due to a division of the third article, which may be accomplished 

 in only one of the antennae of any individual. Two such specimens have been 

 presented. Fig. 110. K and M, are antennas of two individuals, having one 

 five-articled and one six-articled antennse. Unfortunately the one described 

 had two five-articled antennse only. 



Figure llOL, shows the normal antennae, though there is some difference 

 in size due to the difference in the size of the specimens. 



Since this form has apparently never appeared on plants above ground 

 it might seem probable that the wings are not used in flight, and hence the 

 rudimentary structure of the veins. Time and study, however, only can 

 prove that this is not some migrant form. At any rate the insect is very in- 

 teresting and offers a splendid opportunity for studies in variation. 



