OF WASHINGTON, VOLUME XVII, Hii:, .1 1 



(5) GRASSI and FOA, (1908) Madri radicole con caratheri ninfali. 



Rendi. della Regio. Ac-cad, du Lineei, Classe de Scienzc, vol. 

 xvn, Ser. 5 a , Sem. 2, p. 349-359. 



(6) HUNTER, S. J., (1909) The (lre.cn Bug and its Enemies. Hull. Tim. 



Kans., vol. ix, no. 2, pp. 108-116. 



(7) MORDWILKO, A., (1909) Beitriigc zur Biologie de Pflanzenlau-r. 



Aphididae Passerini. Biol. Centrabb.. Bd. 29, Xo. 4, p. S5. 



(8) MortiT/, F., (1893) Beobachtung und Versuche, betreffend die 



Reblaus, Ph. rnxtulrix PI. und deren Bckampfung. Arbeit, a. d. 

 Kais. Gcsund., Bd. 8, p. 532. 



(9) NUSSLIN, O., (1909) Die neureen Ergebnissc und Aufgaben der 



Chermes-Forschung. Zool. Zeit., Bd. xvi, N. 21, 22. 



(10) STAUFFACHER, HCH., (1907) Zur Kenntnis der Phylloxera raxtaln'.r. 



Zeits. f. Wiss. Zool., Bd. 88, p. 135. 



(11) WEBSTER and PHILLIPS, (1912) The Spring Grain- Aphis, or "Green- 



Bug." U. S. D. A., Bu. Ent. Bull. 110, p. 81. 



EXPLANATION OF PLATE X. 



Fig. A, Normal alate. 



Figs. B-D, Variation in venation in alate wings. 



Fig. E, Intermediate wing; greatest development. 



Figs. F-K, Intermediates, showing series between alate and apterous 

 condition. 



Fig. L, Normal apterous. 



Fig. M, Normal pupa. 



Fig. N, Antenna of normal alate, showing sensoria on third segment. 



Figs. O-Q, Antenna? of intermediates, showing degeneration of sensoria. 



Fig. K, Antenna of normal apterous aphid, showing absence of sen- 

 soria on third segment. 



Mr. Barber objected to the term "adults" being assigned indis- 

 criminately to the reproductive stages of the aphids by Messrs. 

 Bilker and Turner. He believes that the aphids should be looked 

 upon as reproducing more through an extreme form of pa-dogeiiesis 

 than as simply agamic females, but that it is very hard to draw 

 a line between simple parthenogenesis and its more complex type 

 that is called psedogenesis. lie believes that the term "adult" 

 is more strictly applicable to forms in which less divergence is 

 found from the normal bisexual mode of reproduction. This 

 normal sexual reproduction is impossible in the so-called agamic 

 "adults" of the aphids which might be regarded as larviu so 

 similar in structure throughout all their stages to the true adults 



