OF WASHINGTON, VOLUME XIV, 1912. 161 



SYMPHOROMYIA AS A BLOOD-SUCKER. 



(Diptera, Leptidse.) 

 BY FREDERICK KNAB and R. A. COOLEY. 



When preparing his paper on blood-sucking Leptidsc* the 

 senior author was unable to find more than the single original 

 observation, by Osten Sacken, of the biting habit in Sympho- 

 romyia. As the result of conversation, during the last meet- 

 ing of the American Association for the Advancement of 

 Science, and subsequent correspondence, Professor Cooley sent 

 him specimens taken in the act of biting, together with the 

 notes reproduced below. Three specimens with the number 

 143 attached, taken at Sedan, Montana, July 1, 1906, are all 

 females of the same species. The material came to hand too 

 late to be incorporated in the above-mentioned paper. 



As it is evident that the blood-sucking habit in Sympho- 

 romvia is confined to certain species, perhaps a single one, the 

 determination of specimens that have actually bitten is of con- 

 siderable interest. There was some difficulty in determining the 

 specimens, as it proved that Symphoromyia is systematically 

 in a rather unsatisfactory condition. However, the specimens 

 fit very well the description given by Williston for the female 

 of his Symphoromyia pachvceras. The proximity of the two 

 regions, northern California for Williston's specimens and 

 southwestern Montana for Professor Cooley's, make the agree- 

 ment reasonably probable. Whether Osten Sacken had the 

 same species under observation probably can only be deter- 

 mined by examining the original specimens, if these are still 

 in existence. We have been unable to trace the locality, Webber 

 Lake, California, given by Osten Sacken, and, moreover, we 

 know very little of the distribution of the species of Sympho- 

 romyia. Attention must be called to the fact that the specimen 

 standing as S. packvceras in the National Museum collec- 

 tion, and upon which Coquillett based his diagnosis, are not 

 Williston's species. This is evident from the shining black ab- 

 domen. Williston describes his species as "gray pollinose," 

 indicating this condition for both thorax and abdomen; in 

 this the Montana specimens agree. The color of the third an- 

 tennal joint, palpi, and legs, which have been freely used in 

 differentiating the species of this genus, are, as might be ex- 

 pected, subject to some variation which probably depends 

 not only upon age, but also upon food. 



There is considerable diversity in the mouth-parts of dif- 

 ferent species of Symphoromyia. The specimens taken by the 

 junior author have rather short mouth-parts with a broad, 



"This volume, pp. 108-109. 



