THE CANADIAN ENTOMOLOGIST 89 



i 



APHIS SALICETI (KALTENBACH), SIPHOCORYNE 

 PASTINAC^ (LINN.), AND ALLIED SPECIES. 



BY C. P. GILLETTE AND L. C. BRAGG, FORT COLLINS, COL. 



It is the object of the authors of this paper to give the results 

 of their studies on a half dozen species of aphides that are quite 

 similar in general appearance, and all but one of which have the 

 willows for their winter hosts, in the hope that they will clear 

 away some confusion and prevent further mixing of data. We 

 believe we have the structural characteristics and food habits well 

 enough worked out so that these species may be readily separated, 

 whether from their winter or summer hosts, by use of the following 

 simple key: 



Cornicles cylindrical or slightly tapering. 



Pre'-caudal spine on dorsum of 8th abdominal seg- 



- ment Aphis theobaldi, n. sp. 



No pre-caudal spine on 8th abdominal segment. A phis saliceti. 



Cornicles distinctly clavate. 



With pre-caudal spine on 8th abdominal segment, 



. Joints 4, 5, 6 and spur sub-equal Siphocoryne caprece. 



Spur equal to joints 4, 5 and 6 com- 

 bined Siphocoryne essigi, n. sp. 



Without pre-caudal spine on 8th abdominal segment. 



Antenna shorter than the body Siphocoryne pastinacce.. 



Antenna longer than the body Siphocoryne grahhami. 



In order that others interested in these species may look up 

 the literature readily, we are giving references to the more im- 

 portant papers: 



Aphis saliceti Kaltenbach. 



Aphis saliceti, Monographic der Fam. der Pflanzenlause, p. 103, 

 1843. 



Koch, Die Pflanzenlause, p. 118, 1857. 

 Buckton, Monograph of British Aphides, vol. II, p. 52, 1879. 



Siphonophora salicicola, n. sp., Thomas, Bui. 2, III, St. Lab. Nat. 



Hist., p. 8, 1878. 

 Aphis salicicola, Monell, Bui. 5, U. S. Geol. Surv., p. 24, 1879. 



Oestlund, Aphidida? of Minn., p. 63, 1887. 



March, 1018 



