Posted by John Carr on 06-09-2013 12:29
#1
On a beach in California, USA near the Mexican border. August 18, 2013.
Edited by John Carr on 06-09-2013 23:18
Posted by Eric Fisher on 06-09-2013 23:05
#2
Proctacanthus coquillettii, male. Nice shot of this sand dune-loving fly limited to the southern part of the Colorado River drainage.
Posted by John Carr on 06-09-2013 23:18
#3
Thanks. Is beard color sexually dimorphic? I also saw a robber fly with white beard.
Posted by Eric Fisher on 13-09-2013 07:19
#4
Yes, the female has a white beard and the body is paler in color (being gray, with the apex of the large ovipositor shiny black). The wings of the male have a large brown spot that covers most of the middle third of the wing, while the female has nearly entirely clear wing, with just a faint brown shadow in the middle third.
Some males of Proctacanthus coquillettii have whitish beards. The intensity of the yellowish-orange color hairs in your male fly seems unusual, and most males have these hairs a much paler yellow color or even white.