Length: The fly shown here measured 4.4 mm from the front of its eyes to the rear of its wings
One trait that sets the genus Minettia apart from similar genera is that the ocellar bristles are essentially parallel, and are longer and stronger than the post-ocellar bristles.
The obscura group of Minettia flies is a troublesome group to would-be identifiers. The fly shown here is in the obscura group, and we are labeling it Minettia cf. obscura. As far as the range of the species Minettia obscura itself, Stone (1965) says nothing more than "published records are unreliable."
American Insects site