102 Psyche [October 



NOTES ON THE SPECIES OF THE GENUS DIOCTRIA. 



By Charles W. Johnson, 

 Boston Society of Natural History. 



On a window of the Boston Society of Natural History, I ob- 

 tained, June 28, 1916, a specimen of Dioctria, but being unable to 

 identify it at the time it was set aside to await more material. On 

 July 6, 1917, while walking along Rawson Road, Aspinwall Hill, 

 Brookline, Mass., I caught four specimens of the same species — 

 two males and two females. After a careful study and comparison 

 with specimens in my collection from Lyndhurst, New Forest, 

 England (cf 9 ) determined by E. E. Austin, I can only refer it to 

 Dioctria haumhaueri Meigen. Wishing to see if the species was 

 still to be found, I visited the place again this year (July 4) and 

 captured five males and four females. 



The sudden appearance and apparently restricted distribution 

 of a species after so many years of careful collecting in the vicinity 

 of Boston, would indicate a comparatively recent introduction, 

 possibly on the root of some plants, many of which have in the past 

 been mported. The species can be distinguished by the following 

 diagnosis. 



Dioctria baumhaueri Meigen. 



Face black with silvery white tomentum, mystax white, front 

 and vertex black, shining, antennae black, third joint about as long 

 as the first and second together. Thorax with a sparse yellow 

 tomentum having two narrow lines of black, a transverse band of 

 white tomentum on the pleura extends to the front coxse, also with 

 irregular patches above the middle and posterior coxse, all the 

 coxse with long white hairs below. Abdomen black, shining. 

 Front and middle legs yellow, a line on the upper side of the femora, 

 tips of the tibise and tarsi black, posterior legs black, a spot on the 

 under side of the femora at the base, and the base and tip of tibiae 

 yellow. Halteres light yellow, wings hyaline. Length, 9-10 mm. 



In Psyche, vol. 24, p. 117, 1917, Mr. Nathan Banks described 

 several new species, some of which were formerly confused with 

 Dioctria albius Walker, but readily separated by the male genitalia. 

 In going over my collect' on in connection with this paper, I have 



