Moved from Subgenus Pachyconops.

If one goes carefully through the key in Camras (1955) and eliminates from consideration the (many!) "Mexico and south" species one arrives at P. floridanus here.

But many characters referred to in that key are not visible in this image, so getting through the key entails a lot of indirect elimination of alternatives. For instance, the frons is not clearly visible in this profile shot, but if one goes "both ways" at couplet 26 (i.e. "front" (=frons) entirely black vs. front with yellow or reddish), then either way leads to P. floridanus. At couplet 45 (where, again the presence or absence of a "T" on the frons is not clear here) the (approximately) equal lengths here of the 2nd & 3rd antennal segments eliminates C. nigrimanus, leaving couplet 53 as the only alternative. And near the end it comes down to facial grooves entirely dark vs. pale. Again, the facial grooves are not visible here, but the only alternatives in our area are P. floridanus and P. discalis...and the latter is restricted to the western U.S.

Reinforcing the ID, a comparison of the two conopids in the image here with the description of P. floridanus in Camras (1955) yields a good match.

But this is not actually a male/female pair. Note that in Camras (2007)(1) it is emphasized that female P. floridanus (and P. weemsi) have long thecas. Neither of the two in this image appears to have a theca. So these are both males. (Males sometimes mount other males...for instance, see here.)

Moved from Physoconops.

Moved from Conopinae.

Moved from ID Request.

Looks like a thick-headed fly pair in the genus Physocephala -- color and location indicate Physocephala texana as seen here http://bugguide.net/node/view/326275/bgpage