One more sand scene

During a walk not too long ago, a small insect caught my eye.  It was puzzling at first because I could see movement when it took off, but when I tried to spot the insect that had flown (once it landed), it was really hard to find.  I started to move slowly and really concentrate, and there it was.  Here's a somewhat zoomed in view:

 

Such amazing camouflage against the sand!  This fly looked mostly white when flying, but on the sand you could see strong black and white coloration (the wing veins are especially striking):

 

 

We found a few individuals, and I started to notice that some looked different.  One form had larger eyes that touched in the middle (see first photo in this post) along with a relatively short abdomen (the abdomen didn't really extend beyond the wings).  The other form had smaller eyes with a gap in the middle (see previous and next photo) along with a longer, tapered abdomen (obviously extending beyond the wings):

 

Later, after determining that these are likely stiletto flies (perhaps Acrosathe vanduzeei?), I also learned that the larger-eyed individuals are males and the individuals with longer abdomens are females.

Eric was very patient and crept up on one of the flies.  Check out this close-up!  [The fly is only ~1 cm (0.4 inches) long.]

 

 

This was my first experience with stiletto flies.  At first I thought they might have been robber flies, but that didn't seem quite right.  I'll have to do some research to learn more about this group, but I wanted to introduce you to this intriguing fly!