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The relatively narrow abdomen and the form of the terminalia indicate a male...which is also suggested by the (presumed) waiting behavior above the larval pits (i.e. hoping to encounter females either visiting the prime larval habitat here to oviposit, or those potentially soon eclosing from pupae buried in the sand below).

As currently circumscribed, there are two species of Vermileo in the western US. I'm assuming this is V. comstocki based on the "smoky" wings, and the location. Another discriminant is color of the palps (dark for V. comstocki; pale for V. opacus)...which I did not see or photograph here, but which I did photograph in a male seen the evening before at a locale a few miles away:

     

Regarding palp color in distinguishing the two species, see the comments here and here.

Regarding wing venation — note the the discal cell here (i.e the closed cell near the center of the wing) has three veinlets emanating from its apical edge...which constitute the distal branches of the medial vein, usually labelled M1-M3 (cf. labelled figure here). In this Vermileo, the most posterior of those veinlets (i.e. M3) forms a short spur which terminates about 1/3 the distance to the wing margin. I don't know whether this might be of diagnostic significance vs. simply interesting "individual variation". But I'm presuming the latter: since it seems M3 is similarly truncate in the right wing of Joyce's image below...while nearly lacking in its left wing:

   

And in Graham's image (after zooming-in on the full-size version) M3 forms a very short spur vein (ending about a 1/5 the distance out to the wing margin). Whereas in my other image, from a few miles away, M3 reaches the wing margin.