10 



BULLETIN 1453, U. S. DEPARTMENT OF AGRICULTURE 



The foregoing description has been taken from Melander and 

 Spuler (49, p. 69). 



GENERAL DESCRIPTION 



The flies (PL 1, A, B), 3 as Kedi (58, p. 74) described them, 

 are " small flies resembling winged ants, which immediately after 

 birth skipped about with incredible sprightliness and vivacity so 

 that they seemed to be the embodiment of perpetual motion." Super- 

 ficially this species appears shining black, with reddish-brown eyes. 





Fig. 2. — Skipper flies and three specimens of the common house fly, showing com- 

 parative sizes. X 2 



and wings held flat over the dorsum when at rest. The females are 

 usually larger than the males, and the largest ones are about three- 

 fifths as long as an average-sized house fly and more slender. The 

 comparative sizes of skipper flies and house flies are shown in Fig- 

 ure 2. When feeding and courting the flies are feverishly active, run- 



3 Sibyl Swegman MacDonald, insect delineator with the Bureau of Entomology, pre- 

 pared the drawings shown a.» Figures 2, 3, 8, and 9, and J. G. Pratt, scientific photog- 

 rapher of the bureau, made the photographs. 



