Location= 9 mi. south of Colfax, on Pine Lake Dr., 666 m elevation (2,185 ft).
GPS= 39.0649, -120.9439.

I collected 2 of these in a VFIT (Vertical Flight Intercept Trap) holding 100% Propylene Glycol after 20 days from Aug. 21 to Sept. 10, 2022.

I think it might a crabronid or parasitic bee, but I don't see any like it there.

Any suggestions greatly appreciated.

==================== Additional material added 20 Jan, 2023. ============================
Thanks to Paul De Ley for providing me with the publication including the key to species.

Key to species of Diploplectron (1) helped me determine the species.
Four pictures added to aid identification.
I believe this specimen is D. peglowi because:

1. Dorsal close-up of the clypeus showing the brown projections on the yellow clypeus with a rounded indentation between the projections.

2. Dorsal view of the head showing the relative position of the ocelli. Not an equilateral triangle, but the forward ocellus is further apart from the back ones than they are apart from each other, (D. Brunneipes ocelli = equilateral triangle).

3. Head facing left: base of mandible not meeting the compound eye (it does meet the eye in D. californicum).

4. Pygidium dorsal showing the lateral lines (difficult to catch, more of a dark shade on one side.

5. Not pictured, but the key states: "ratio between least interocular distance and length of flagellomeres 1 and 2 = 1:1.4. I measured my specimen to be 1:1.7 (D. Californium = 1:1.2).

6. Many other characters are easily visible in the pictures like black abdomen.

7. White lower frons and white clypeus is also shared with D. brunneipes, but brunneipes has the mandible meeting the compound eye and I think my specimen's mandible is separated from the eye.