Genus Chrysomya - Hairy Maggot Blow Flies

Chrysomya Robineau-Desvoidy 1830

2 spp. in our area, a dozen total(1)(2)

Robust metallic green flies with a distinct blue hue when viewed under bright sunlit conditions. The posterior margin of the abdominal tergites are a brilliant blue.

Basal section of the stem vein, when viewed dorsally, setose; dorsum of 1st and 2nd abdominal tergites black, posterior margins of abdominal tergites 3 &4 black(1)

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

Another distinguishing feature between the 2 spp. maybe eye colour (in live flies);c. 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. (TT)

native the Old World, adventive in our area (so. US to IL-MI) and Mesomerica(1)