FLIES OF THE GENUS OGCODES — SCHLINGER 295 



and south through Texas to Costa Rica. There are, however, no 

 Mexican records, and the available ones from the Austroriparian Zone 

 of southeastern United States are few (see text fig. 8). 



Recorded distribution: Arizona (doubtful record), District of 

 Columbia, Illinois, Iowa, Maryland, Massachusetts, North Carolina, 

 Pennsylvania, Quebec, Texas, and Virginia. 



New distribution records: (25 specimens, 14 6^, 119.) 



Costa Rica: 1 cf, La Suiza, June 16, 1924 (P. Schild, EIS). 



Iowa: Id^, McGregor, July 1, 1950 (Hicks, Slater, ISC). 



Michigan: Icf, Cheboygan Co., July 18, 1949 (A. C. Reneau, ISC). 



Minnesota: 1 9 , Lake Minnetonka, Enchanted Isle, June 26, 1932 (E. R. 

 Tinkham, UM); 1 ? , Big Stone Co. (O. W. Oestlund, UM). 



New Jersey: Icf, Cape May, Aug. 13, 1896 (W. Stone, PANS); 1 ? , Boon- 

 ton, June 16, 1901 (G. M. Green, USNM); Ic?, 1 9 , Ramsey, June 29, 1941 id"), 

 July 13, 1941 (9), (W. J. Gertsch, AMNH, EIS). 



New York: 19, New Rochelle, June 1, 1932 (L. Lacey, AMNH). 



Pennsylvania: Icf", Pittsburgh (ALM); 19, Swarthmore, Aug. 19, 1906 

 (E. T. Cresson, Jr., PANS); Icf, Westmoreland Co. (CM); Icf, Jeannette, 

 June 21 (CM). 



Quebec: 1 9 , Montreal, July 7, 1912 (E. P. VanDuzee, CAS). 



Tennessee: 19, Knoxville, Sept. 10, 1948 (D. W. Pfitzer, UT). 



Virginia: Icf, Falls Church, Aug. 27, 1916 (C. T. Greene, USNM). 



Wisconsin: 19, Madison, June 22, 1929 (M. H. Doner, UW); 4c?, 29, 

 Milwaukee (MPM). 



Seasonal occurrence: Males have been taken from March 28 

 (College Station, Tex.) to August 27 (Falls Church, Va.), and females 

 from May 8 (Great Falls, Va.) to November 10 (Knoxville, Tenn.). 



Recorded hosts: None. 



Biology: Little has been known until recently. Champlain and 

 Knull (1923) reported locating in Pennsylvania a wasp nest in a log 

 which, when opened, contained several nicely preserved specimens of 

 dispar. Along with these were remains of spiders which presumably 

 were their hosts that had been stored by a spider wasp. Farr (1953) 

 observed this species in Massachusetts in what was apparently a 

 mating swarm. The flies were observed about 12 feet above the 

 ground, and were flying in zig-zag fashion. Occasionally one would 

 depart from the swarm and land on a twig or leaf of a certain white 

 ash {Fraxinus americana L.), which stood about 5 feet high. I have 

 examined several examples of the series collected by Farr and they 

 were typical dispar. 



Discussion: In its lighter coloration and darkened spu'acidar area, 

 this species resembles rufoabdominalis. However, it is phylogeneti- 

 cally much closer to pallidipennis, the females being quite difficult at 

 times to distinguish. 0. dispar appears to be sympatric with palli- 

 dipennis throughout most of the latter's range, with many specimens 

 having the same locality and date. When the mesonotal vittae are 



