THE CANADIAN ENTOMOLOGIST. 28 



o 



A SECONDARY SEXUAL CHARACTER OF APHIDID.^. 



BV JOHN J. DAVIS, 

 Office of the State Entomolog-ist, Urbana, Illinois. 



A character of the oviparous females of Aphids which has been 

 previously mentioned in descriptions, but which, so far as I can learn, has 

 never been treated as a secondary sexual character, is the presence of 

 sensoria upon the hind tibi?e, in consequence of which the hind tibiae are 

 usually noticeably swollen. The term '' sensoria," in Aphid descriptions, 

 was first used by Professor O. W. Oestlund, in his "Synopsis of the 

 Aphididie of Minnesota" (rSSy), in referring to the pores on the antennae. 



Buckton, in his " Monograph of the British Aphides," Vol. I (1875), 

 p. 104, probably referred to these sensorial pores when he wrote, in his 

 description of ihe apterous oviparous female of Siphonophora rosce, 

 Reaum., that " the hind tibiie are furnished with numerous tubercular 

 spots, which probably assist the insect in arranging the soft and glutinous 

 eggs in the recesses of the leaf buds." Also in Volumes I and II of this 

 same work he mentions, in the descriptions of the apterous oviparous 

 females of SipJioJiophora dirhoda^ Walk.; Aphis ede?itula, Buck.; A. primi, 

 Reaum.; A. vibtirni^ Schr.; A. sambucaria, Pass., and Chaitophorus 

 bettdce (?), Buck., that the hind tibias are flattened, expanded or dilated. 



These so-called pores or tubercular spots on the hind tibi» were first 

 referred to as sensoria by Dr. S. A. Forbes, who, in the Eighteenth Report 

 of the State Entomologist of Illinois (1894), mentions and figures them as 

 being conspicuously present on the hind tibi?e of the apterous oviparous 

 females of Aphis maidi-radicis, Forbes. Since then, mention of these 

 tibial sensoria as occurring on the sexual females of Siphocoryne avence, 

 Fabr., and Hormaphis hamamelidis. Fitch, has been made by Mr. Theo. 

 Pergande in Bulletin 44 (1904) and in Technical Bulletin 9 (1901) of the 

 U. S. Bureau of Entomology; by Professor E. Dwight Sanderson, who 

 refers to them as " pores " in his descriptions of the apterous oviparous 

 females oi Aphis pouii, De G.; A, sorbi, Kalt., and A. brevis, Sand, (he 

 also shows these " pores" in his figure of Aphis Fitchii = Siphocoryne 

 ave?tce, but makes no mention of them in his description), in the Thirteenth 

 Annual Report of the Agricultural Experiment Station of Delaware (1892), 

 and in E?itof?iological News (1906), in his description of the apterous ovipar- 

 ous females of Macrosiphum granaria, Buck., he says : " meta-tibiae with 

 numerous pores"; by Miss Edith M. Patch, who, in Bulletin 147 of the 

 Maine Agricultural Experiment Station (1907), mentions and figures the 

 sensoria on the hind tibiae of Macrosiphum solani/o/ii, Ashm.; and by 

 Professor F. L. Washburn, in Canadian Entomologist (1908), who found 

 them present on the hind tibiae of the apterous oviparous females of 

 Toxoptera graminum^ Rond. 



August, 1908 



