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Photo#818239
Agave fly - Hermetia comstocki

Agave fly - Hermetia comstocki
Santa Rita Experimental Range Station, Florida Canyon, Pima County, Arizona, USA
July 25, 2013
On the florida canyon trail, we found this fly that would land on the upper curved side of the agave leaves. gathering_2013

Moved
Moved from Flies.

Stratiomyidae: Hermetia comstocki
Stratiomyidae: Hermetia comstocki

 
Additional ID and gender Q
Norm, I was hoping you might be able to comment on another possible H. comstocki:



...and address the question of whether the sexual color dimorphism in that species, mentioned without elaboration in Alcock's paper (see my comment below), can be made more explicit with the rough rubric:

          thorax mostly black → male     vs.     thorax mostly brick-red → female

At the current time, the lack of gender determination for any of the BugGuide H. comstocki posts is somewhat odd (and intriguing...I know from the key in the MND that male Hermetia are not holoptic, so that "easy" character doesn't work).

Further circumstantial support for H. comstocki
I found an interesting article describing lekking behavior of H. comstocki on agave leaves:

  Alcock, John. (1990). A large male competitive advantage in a lekking fly, Hermetia comstocki Williston (Diptera: Stratiomyidae). Psyche 97:267-280 (Full Text)

I'm guessing the behavior described therein is consistent with what you observed with this fly on the Florida Canyon trail.

Among the references listed in that paper are:

  James, M. T. (1935). The genus Hermetia in the United States (Diptera, Stratiomyidae). Bull. Brooklyn Ent. Soc. 30:165-170.

Unfortunately, I couldn't find that paper on the web...it would probably help confirm the ID here (and in my post here). [Postscript 9/2/2019: James(1935) is now available via BHL.]
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Also, regarding determining male vs. female...Alcock states at the bottom of his 2nd page that:

"The high degree of sexual dimorphism in this species facilitated identification of the sexes (females are usually much larger than males and are differently colored as well)."

I wonder if the black thorax coloration corresponds to males (the behavior of your fly seems consistent with that of males, as described in Alcock)...while the more reddish thorax coloration in my post might correspond to females? (The behavior of the fly in my post did not fit that described for males in Alcock...and I recall no agave or yucca at that locale.)

Alcock also mentions (in 2nd paragraph of 3rd page) that, due to behavioral reasons: "The operational sex ratio was clearly highly skewed toward males." That might partially account for the fact that most of the current BG posts have mostly black thoracies, while just Bob Behrstock's (and my post) have mostly red thoracies.

Hermetia comstocki?

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