SEASONAL AND CLIMATIC VARIATION IN CERODONTA. 



By J. M. Aldrich, 

 U. S. Bureau of Entomology, West Lafayette, Indiana. 



Cerodonta dorsalis is a small fly of the family Agromyzidas 

 (sens, str.), the larva of which mines in the leaves and leaf- 

 sheaths of wheat, timothy, etc. It is very widespread in the 

 United States and Canada. 



It was described by Loew (a) in 1863, the type being a female 

 from the District of Columbia. He referred it to the genus 

 Odontocera Macquart (b), a preoccupied name, for which 

 Rondani (c) had proposed to substitute Cerodonta, and a year 

 later Schiner (d) had proposed Ceratomyza. 



In September, 1913, Melander (e) restored Rondani's over- 

 looked generic namej and separated his North American material 

 into two species on color characters; one he called dorsalis 

 Loew, represented from Massachusetts, Louisiana, Illinois, and 

 Texas; the other he identified with the European species 

 femoralis Meigen, represented from Montana, Wyoming, Idaho, 

 Washington, British Columbia, Oregon, and California. The 

 latter species he compared with European specimens deter- 

 mined by Strobl. 



A few days later, about Oct. 1, 1913, Malloch (f) published 

 his large revision of Agromyza and also took up this genus 

 Cerodonta (he used the original but evidently erroneous spelling 

 Cerodontha). He recognized but one North American species, 

 dorsalis, not considering the variations in color to be of specific 

 importance. The National Museum material, with which he 

 was working, was from eighteen States, Atlantic and Pacific 

 among them, and also from Mexico and Porto Rico. Neither 

 Melander nor Malloch knew until about the time of publication 

 that the other was working upon the group, and the two con- 

 clusions were arrived at independently. 



When I began in 1913 to do some biological work on the 

 group, the difference of opinion between two prominent dip- 

 terists as to the species limits presented itself as a problem to 



*Publi.shed by permission of the Chief of the Bureau of Entomology. 

 tMr. Mallock has called my attention to an earlier use of Ceradonta by Collin, 

 Ent. Mo. Mag., Nov. 1911, p. 254. 



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