STUDIES ON APHIDIDiE. IL* 



John J. Davis. 



OFFICE OF THE STATE ENTOMOLOGIST, URBANA, ILLINOIS. 



The Birch CalHpterus. 



[Callipterus bctiilcEColens (Fitch) Monell.] 



What is supposed to be this species was first described by Asa 

 Fitch in his "Catalogue of the Homoptera of New York" in 185 1 

 as Aphis betulcecolens. ]\Ionell described it from Missouri as 

 Callipterus heinlacolens, n. sp., and placed Aphis betiilcecolens of 

 Fitch as doubtfully synonymous. Thomas hesitatingly placed 

 this species and Calaphis betidella as Callipterus betulce of Koch, 

 but there is little doubt that all three are distinct species. Oest- 

 lund redescribed the winged viviparous female, from specimens 

 collected in Minnesota, as C. betulcecolens (Fitch), and gave C. 

 betulcBcolens of Monnell as synoynmous. It has been further 

 reported in the literature by Miss Edith M. Patch from Maine, 

 and by W. T. Clarke from California. 



In Illinois I have found it a very common species on Betiila 

 alba, and it doubtless occurs wherever the birch is found. It 

 became very abundant this fall (1908), especially at the time the 

 sexual forms appeared. 



The viviparous females were found on birch throughout the 

 summer and as late as September 28. at Chicago, Illinois. The 

 oviparous females, winged males, and eggs were first noticed 

 September 21, 1908, and at that time many pairs were observed 

 in copula. Careful observations were made to determine whether 

 or not the hind tibise of the oviparous females, which in this species 

 always bear sensoria, played any part in copulation or oviposition, 

 it having been stated by R. A. Vickery ("A Comparative Study 

 of the External Anatomy of Plant Lice." p. 11. Separate of 

 the Twelfth Report of the State Entomologist of Minnesota, 1908) 

 that the hind tibiae of oviparous female aphids have some func- 

 tion in connection with oviposition. The hind tibias of the 

 oviparous females of this species, however, played no part what- 

 ever in oviposition, nor, so far as could be observed, in the act 



* For No. 1 of this series see the Annals of the Entomological Society of 

 America, Vol. I, No. 4, December, 1908, pp. 251-264. 



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