Numbers
Edit TT: 2 species in NA, currently (May 2008) lumped together in BG as rufifacies; 2nd sp. is megacephala (Whitworth 2006)
Identification
Adults are robust flies metallic green in color with a distinct blue hue when viewed under bright sunlit conditions. The posterior margin of the abdominal tergites are a brilliant blue.
Edit TT: Calliphorid flies with the basal section of the stem vein, when viewed dorsdally setose; dorsum of 1st and 2nd abdominal tergites black, posterior margins of abdominal tergites 3 and 4 black (Whitworth 2006, p. 693).
Edit TT: Decent close-up shots of anterior thoracic spiracle and head and are needed to ID an individual to species, viz:
- vestiture of anterior thoracic spiracle: dark brown or dark orange in
megacephala; looks like this
may be an orange spiracle
spiracle pale or white in rufifacies;
- genal dilation with orange ground colour and orange setae in megacephala; genal dilation with pale dusting and pale setae in rufifacies.
Male eyes are perhaps the most useful character, viz:
- upper facets enlarged and sharply demarcated from smaller facets in lower third of eye in
megacephala 
- eye facets small throughout in rufifacies;
- frons very narrow with eyes nearly touching megacephala see thumbnail under eye facets;
- frons broader rufifacies;
Edit: TT: another distinguishing feature between the 2 spp. maybe eye colour (in live flies). Megacephala appears to have bright red/orange eyes whereas rufifacies has browner brick-red eyes. This feature is not mentioned in any of the keys I have seen; probably because the dipterists have been working with pinned material with faded eyes. BG has several images of live flies.
Range
It is now established in Southern California, Arizona, Texas, Louisiana, and Florida. It is also found throughout Central America, Japan, India, and the remainder of the old world.
Edit TT: The above presumably refers to rufifacies and should include: New Mexico, Illinois, Michigan (Whitworth 2006); BG has photos of a specimen from Oklohoma.
C. megacephala found in: South Carolina, Georgia, Florida, Alabama, Texas, New Mexico, California (Whitworth 2006).
Print References
Whitworth, T. 2006. Keys to the genera and species of blow flies of America north of Mexico. Proc. Entomol. Soc. Wash 108(3): 689-725
