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This fly was seen in middle July at San Diego Botanical Gardens. Please any help with the ID? Thanks!

http://foro.infojardin.com/threads/diptera-moscas-iv.62365/page-55#post-1145553

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The Tachinidae is Archytas californiae or Archytas apicifer.

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Fantastic news! There is a way of distinguish both species, even just by probability (for example one more frequent)?

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Both species are common. There are similar, rarer species elsewhere in the United States.

According to the last revision (Ravlin and Stehr 1984), the color differences between the species in this group are

marmoratus, analis, and apicifer: "Discal setae on thoracic notum black; thoracic pollen gray to yellow-gray; parafacial pollen silvery-white to off-white."

californiae and nivalis: "Discal setae on thoracic notum yellow to white or mixed with black (especially prevalent on the scutellar disc when viewed posterolaterally); thoracic pollen golden-yellow- to yellow; parafacial pollen golden-yellow to yellow."

I don't know how reliable these color differences are. I think there is overlap. The male genitalia are quite different.

Color of discal setae means color of small hairs. The major bristles are black in both species.

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Ok, big thanks! I never had heard before about "pollen" as a feature of an insect body. I suppose that are powdery pruinescence, and then I think that it's clearly yellowish more than grey, what would lead to vote maybe for californiae better. In my images I'm unable to see smaller bristles, only bigger setae...
I think that (being not much prudent, haha) I can tag it Archytas cf. californiae :) Thanks a lot!