PROC. ENT. soc. WASH., VOL. 22, NO. 2, FEB., 1920 27 



B. Mystax chiefly black, lower third or less grayish or pale yellowish; 

 ovipositor slender as long as last three abdominal segments or 

 longer; male with from 2 to 5 silvery segments before hypopygium 



aestuans. 



BB. Mystax chiefly grayish or yellowish, sometimes a few black hairs 



above. 



C. Ovipositor strongly compressed, equal in length to last 3 or 4 

 abdominal segments; segments 4 to 6 of male silvery and 4 

 especially with long silver-white hair parted in the middle and 



directed outwards nemoralis. 



CC. Ovipositor not so compressed, not longer than last two abdominal 

 segments together; male without parted long silvery white 

 hairs on dor sum. 



D. Median dark markings of pronotum precurrent or nearly so; 

 larger species (25-30 mm.) , upper valve of hypopygium, bifid 



as seen from side maculatus. 



DD. Median dark markings traversing only two-thirds of prono- 

 tum; smaller species (20-25 mm.), upper valve of hypo- 

 pygium, not bifid as seen from side albibaris. 



E. aestuans Linnaeus. Abundant ; June 20 to September 20; 

 in copula, August 1, 12 and 19. Has been seen ovipositing in 

 old cedar post and on twigs of red cedar (Juniperus virginiana) 

 and on bark of tulip tree (Liriodendron). Sarcophaga sp. has 

 been identified among the prey. .The extent to which the seg- 

 ments of the male abdomen are silvered is quite variable, and 

 has been the cause of the species receiving several names. So 

 far no one has demonstrated correlation of varying degrees of 

 this character with any other differences acceptable for specific 

 distinction. The small form with four segments silvery is macro- 

 labris Wied. P. I. 



E. albibarbis Macquart. Common in the Coastal Plain, as at 

 Hyattsville, Beltsville and Odenton; June 25 to September 10. 

 Among the prey have been noted the digger wasp Tachysphex 

 sp. ; the muscid fly, Lucilia sp. and a Tachinid. 



E. maculatus Macquart. Washington, D. C., Banks. 

 E. nemoralis Hine. Mt. Vernon, Va., August 20, 1916, July 4 

 and 13, 1917, McAtee; a southern form for which this is the north- 

 ernmost record; the species perches chiefly in trees. 



E. rufibarbis Macquart. Very common; June 24 (the next 

 date is July 23) to October 8; in copula September 2, 17, 19 

 and 23. 



Mallophora Macquart. 

 Key to the Species. 



A. Length, including wings, more than 25 mm.; wings blackish orcina. 



AA. Length, including wings, less than 20 mm.; wings hyaline or smoky. 



. .da us it did. 



