14 ENTOMOLOGICAL NEWS. [Jan., 'lO 



Chaitophorus negundinus Thos. vs. C. aceris Linn. 



By JOHN J. DAVIS, 

 Office of the State Entomologist, Urbana, Illinois. 



In ENTOMOLOGICAL NEWS for March, 1908 (Vol. xix, p. 

 131-132) Professor O. W. Oestltind gave a synopsis of the 

 known life history of the dimorph of Chaitophorus aceris 

 (testudinatus of Kessler) as worked out in Europe and sug- 

 gested the possibility of Ch. negundinis, which produces 

 dimorphs similar to those of aceris, being a synonym of the 

 European species just mentioned. The dimorph of Ch. 

 negundinis had previously been written about by Mr. L. C. 

 Bragg in ENTOMOLOGICAL NEWS (Vol. xviii, Dec. 1907, p. 431- 

 432), and later by the writer in the Annals of the Entomolo- 

 gical Society of America (June, 1908, p. 130-32), in both 

 cases the so-called box-elder aphid, Ch. negundinis, being con- 

 sidered distinct from the European maple aphids, Ch. aceris, 

 et spp. At the same time I wrote to Dr. G. Del Guercio. 

 sending him specimens of negundinis and requesting his opin- 

 ion as to the distinctness of aceris (testudinatus of Kessler) 

 and negundinis. He very kindly made a careful examination 

 and reported the two species as distinct, and also sent me 

 specimens of both the normal and the leafy dimorphic forms 

 of aceris, together with sketches showing the variable dark 

 patterns on 'the dorsum of the "normal" wingless viviparous 

 females. 



Dr. Del Guercio writes, "In aceris, * * * * one will al- 

 ways find it furnished with thin long hairs. The length of 

 such hairs is about 20 microns and they lay about small tuber- 

 cles, which are generally brownish, and distinct or indistinct, 

 in a dark mass on the back. * * Ch. negundinis, at least 



in those sent me, are furnished with rather rigid and short 

 hairs, which measure 6 to 7 microns. This characteristic 

 seems to me very important and less variable than any other 

 in the two species." Following 'this suggestion I have exam- 

 ined all of the specimens of the winged viviparous temales of 

 Ch. negundinis in my collection and find the length of the 



