THE CANADIAN ENTOMOLOGIST. 313 



TACHINID.^, NEW AND OLD. 



BY \V. R. THOMPSON, ITHACA, NEW YORK. 

 (Continued from \'ol. XLIII, p. 272 ) 

 Acronariita mirabilis Town. 



This species was described by Mr. Townsend (in Tax. iVIusc. Flies, 

 p. 86), from a single specimen collected by Dr. H. G. Dyar at Palm 

 Beach, Fia. The type specimen seems to be a male, not a female. In 

 the genus Sthizotachi?ia and related genera, of which this is one, the 

 secondary sexual characters, such as holopticism, the absence of orbital 

 bristles, and long claws and pulvilli in the male sex, are not apparent. 

 The only certain method, therefore, of determining the sex of a specimen 

 is by an examination of the genitalia. The close relation of the genus 

 Acrojiarista to Schizotachifia would seem to indicate that the incised third 

 antennal segment is in itself likely to be characteristic of the male sex, and 

 an examination of the genitalia oi Acronarista has confirmed this view. 



The males of the two genera may be separated as follows : 



Arista inserted at two-thirds the distance from base to apex of third anten- 

 nal segment ; palpi cylindrical, quite small Acronarista Town. 



Arista inserted close to the base of the third antennal segment ; palpi well 

 developed, often more or less broadened and 

 flattened Schizotachina Walk. 



±Meiopia Meigen. 

 Among a number of Tachinids collected in the neighbourhood of 

 Boston, Mass., I found a number of specimens which I at first thought to 

 be females of Metopia leucocephala Rossi. An examination of the geni- 

 talia, however, showed that both sexes were present, and upon more 

 careful study I found good characters for i he separation of both males and 

 females from those of leucocephala. The specimens were submitted to 

 Mr. Coquillett, who determined ihem as Metopia lateralis Macquart. 

 This species was described by Macquart in Dipt. Exot., Sup. Ill, p. 208 

 (48), 1847, as De^^ceria lateralis. The species was placed by Mr. 

 Coquillett as a synonym of M. leiicocephala in his '"Revision." Only 

 females were in tl"!e U. S. N. M. collection, and these differ so little from 

 the females of leucocephala that their separation did not seem warranted. 

 The species may be separated by the following key : 



I. Frontal vitta and parafrontals dark brown on posterior half, somewhat 

 polished, parafrontals very thinly dusted with silveiy-pollen on the 

 anterior half and apparently including the frontal vitta, shining^ 



September, 1911 



