[Syrphidae] syrphid developmental defect? or visual efect?

[ximo mengual sanchis]

Dear friends,

I'm not a big fan of these things but this forum has an interesting gif
image (animated picture). My friend Keith sent me the link of a flower fly
(Epistrophe eligans) with a weird "visual efect". There appears to be a
mobile hole in the fly's face that opens when it moves its proboscis, the
gif is mesmerizing and a little grotesque. What do you think caused this?

http://www.fredmiranda.com/forum/topic/1005789


Best regards,

Ximo



-- 
********************************************************
Dr. Ximo Mengual
Department of Entomology
Smithsonian Institution
PO Box 37012, MRC-0169
Rm CE-607
Washington, D.C. 20013-7012
Phone: +1 (202) 633-1004
e-mail: mengualj at si.edu
http://entomology.si.edu/StaffPages/MengualJ.html

For FEDEX:
Smithsonian Institution
National Museum of Natural History (NHB)
Department of Entomology
10th & Constitution NW
Phone: +1 (202) 633-1004
Washington, DC 20560-0169
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