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Index of Subjects Hi Angus, There's not enough info in the either image to definitively identify either of your specimens on appearance alone, unless someone recognizes either one explicitly as a locally-known species, apparently what Chris and Dave were doing. Tachinids are the largest family of recently evolved flies (perhaps largest of all in terms of numbers of species), close to blowflies and their kin, difficult to identify as to species. If you see a very bristly fly like yours, it's likely a tachinid unless it's a robberfly (Asilidae), but asilids are more ancient and have a much different antennal tip (this antenna is "modern"). This general group of "calyptrates" including tachinids is distinguished by a fleshy lobe at the base of the wing, the calypter, clearly visible as a white area in the photo, so this rules out most of the other modern groups (the acalyptrates). The calypter has been suggested to increase flight manoeuvrability. So, bristly calyptrate = it's likely a tachinid. The third segment of the antenna (funiculus, or 3rd flagellomere) is the main olfactory organ in these flies, much studied recently in _Drosophila_. In your specimen it is more prominent than often found, another feature sometimes seen in tachinids. This is loose stuff from me as none of these features are cast-iron identifiers, but I'd still vote Tachinidae. For an informative professional site on the latest phylogeny of Diptera try googling Flytree. One link from there will get you to a useful Atlas site run from CSIRO in Canberra, Australia, which has a strong Diptera group. This has a very detailed listing of named external parts of flies (which light up when you type 'calypter' etc.), particularly the various unmemorable groups of body bristles that are often used in detailed run-downs of species in keys. It covers several levels of fly phylogeny -- four, I think. Direct link for the Atlas is www.ento.csiro.au/biology/fly/fly.html# Pick the Musca example for your tachinid(?) fly. It's in the sister group. Steve ************************************* Quoting Angus MacLean <angusmcl@ns.sympatico.ca>: > I appreciate you calling me on this one, Stephen, as I know virtually > nothing about the differences. This other photo shows the wing(s) > clearly and I thought the clear vein (on the right) was the spurious > vein of the mimic. > http://www.flickr.com/photo_zoom.gne?id=239985082&size=o > Which features of the other image leads you to believe it is a > "tachinid" fly. In this pic I have difficulty seeing the features > mentioned in the NAS Guide. > Thanks, > Angus --
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