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JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



alate forms had clavate cornicles and a strong tubercle on the inner 

 surface of the second joint of the antenna. 



Not having the papers of Walker and Passerini, I shall have to omit 

 their comments, but Buckton has evidently made the same mistake 

 as Koch in confusing the two species except that he has figured what 

 seems to be the apterous form of hippohces and the alate form of hraggii, 

 and mentions as food plants species of Galeopsis, Lamiiim. Stachys, and 

 Polygonum, and states that the specimens figured were from Polygonum 

 persicaria in September. 



Schouteden evidently had the true sexual forms of hippohces, both 

 of which he described with clavate cornicles, the specimens figured 

 being from Hippohces rhamnoides and Elceagnus sp., but he does not 

 mention the date. 



Davis, in his paper in Annals, 1908, describes and figures the winged 

 and wingless viviparous female, and the oviparous female, and refers 

 to the original descriptions of Myzus hraggii in Canadian Entomologist, 

 January, 1908, for the characterization of the winged male and the 

 winged and wingless viviparous females, but hraggii always has cylin- 

 drical cornicles so that, once more, the two species were confused. 



There is no doubt which species Davis had as he describes the cla- 

 vate cornicles and gives a good figure. Professor Davis also took his 

 specimens on Elceagnus in September. 



Then, in his paper in Journal of Economic Entomology for 1911, 

 p. 325 and plate 10, Mr. Davis has given descriptions and figures of 

 hippohces which seem to be identical mth his descriptions of elceogni 

 (hippohces) in Annals, mentioned above. It seems that Davis either 

 made a mistake in sending del Guercio a cylindrical, cormcled hraggii 

 (hippohces) for determination, or else del Guercio made the mistake of 

 overlooking the cylindrical cornicles in the specimens Davis sent. If, 

 on the other hand, the elceagni described by del Guercio had clavate 

 cornicles, it seems extremely probable that he was working with 

 hippohces. 



At Fort Collins we find hraggii common and often very abundant 

 upon the Canada thistle (Cirsium arvensce) during the latter part of 

 summer and early fall every year, and it also occurs on artichoke, 

 Cynara, Scolymus; the winter hosts are the Russian olive, Hippohces 

 rhamnoides and Shepherdia aruensis. Rhop. hippohces we take upon 

 Polygonum during the summer and upon Russian olive and H. rham- 

 noides during the fall, winter and spring. We have never found the 

 form with clavate cornicles upon the Canada thistle; neither have we 

 found the form with the cylindrical cornicles upon Polygonum, or 

 Persicaria, but both forms occur upon the Russian olive (Elceagnus) 

 and Hippohces, 



