Some type of fast flying beneficial insect
After a brief search online it looks similar to polybiomyia but I can't find any observations of the genus in this area so I'm just going to leave it at Ditera for visibility. Does anyone know of any fly wasp mimics that look like this in the area?
It also appeared to be trying to lay eggs on the bark of a Delonix regia tree.
On a shaded north-facing steep slope ~80-ft south from the OHWM of the South Fork of the Stanislaus River, Tuolumne County, California. ~4680-ft elevation.