1909] Observations on a Gall Aphid 93 



usually supposed, but is morphologically equivalent to a winged 

 vivipara which has lost her organs of flight and all correlated 

 structures through disuse. Living as parasitic insects in the 

 midst of a luxuriant supply of food all superfluous structures have 

 been dispensed with according to the well known laws of para- 

 sitism. When the males of a species are wingless, they must pair 

 with females which have developed on the same plant and which 

 may be of the same descent. The general migration of Aphis 

 atriplicis in August observed by Connold and myself undoubtedly 

 tends to counteract cross fertilization, since the bisexual colonies 

 on any plant in the fall would be of mixed descent. According 

 to the literature which I have seen, wingless males are known in the 

 following species: Pemphigus attenuatus Osborn, Schizoneura corni 

 Fab., 5. americana Riley, 5. lanigera Hausm., Hamanielistes 

 spinosus Shim., Hormaphis hamamelidis Osten Sacken, Chermes 

 and Phylloxera, all species as far as known, Melanoxanthus salicis 

 L., Lachnus nudiis De G., L. piceicola Cholodk., Aphis fnaidi- 

 radicis Forbes, A. atriplicis L., A. mali Fab., A. carbocolor Gil- 

 lette, A. torticauda Gillette. Buckton reports wingless males in 

 ten other species, but since I know the winged males in four of 

 these and since his work seems so generally superficial, I do not 

 give his list. 



Aphis atriplicis was greatly parasitized both at Fredonia and 

 at Forest Hills. On some plants nearly all the aphids were 

 killed. I am indebted to Mr. C. T. Brues, Curator, Public Mu- 

 seum of the City of Milwaukee, Milwaukee, Wis., for the deter- 

 mination of the following parasites which I reared from this spe- 

 cies: Lysiphlebiis aragrostaphidis Ashm., Fredonia, N. Y., Aug. 3, 

 1908. Several specimens. From viviparous aphids. The other 

 parasites were all reared from Forest Hills material and must have 

 developed -very largely in the oviparous insects. Lysiphlebiis 

 eragrostaphidis Ashm., Oct., 10, 23 and 30; many specimens. 

 Pachyneiiron micans Howard. Oct. 30, one specimen. Asaphes 

 rufipes Brues, n. sp. Oct. 30, four specimens. Aphyciis ? sp. an 

 Encyrtid. Oct. 30, one specimen. Figites, sens, lat., aberrant 

 Cynipidcc. Mr. William Beutenmuller suggests that these may 

 belong to the genus, Allobia, known to be parasitic in plant lice, 

 but no one in this country has time to study them for me. Oct. 

 30, nine specimens. 



Several lady beetles were collected from galls of this aphid at 

 Fredonia. Adult examples of these were kindly determined for 



