These are images of a Square-headed Wasp that I believe is most likely a female...?
Full Size Image: Click Here
ID info:
Keying to Genus in Subtribe Gastrosericina:
1. - The large and light-green colored eyes, small eye-gap and short antennae length, fails for the genus Larropsis.
2. - The short, blunt abdominal apex with a wide pygidium, very small eye-gap and thick legs, are features that fail for the genus Tachysphex. Also, the two ocellar scars are club-shaped with long tails, but they are very hard to see.
3. - The overall body shapes, proportions, and the wing vein patterns suggest the genus Tachytes. (incorrect, see comments below)