Host: I believe this was a California Live Oak (Q. agrifolia), but no leaves (aside, typically they'd have leaves but there was a bad CA Oak Moth infestation recently so many of these trees are still without leaves). I will double check later.
Boundary of Fort Ord
I have read in the USDA's "A Field Guide to Insect and Pathogens of CA Oaks"
http://oaks.cnr.berkeley.edu/wp-content/uploads/2019/02/Field-Guide-to-Insects-and-Diseases.pdf
-that crown whiteflies can occur on valley oaks too. This would make a lot of sense given most of the local coastal live oaks have been hammered by California Oakworm/moth.
I didn't have my better cell phone, so after the fact I couldn't tell what this was. At the time, it didn't remind me of whiteflies, wooly oak aphids, or oak leaf phylloxera (at least yellow spots on top of leaves). So in my mind it was a mold.
But perhaps it is just old crown whitefly wax residue from old nymphs/pupae? In that case my suggestion of fungi would be off.
male Lawrence's GF
Observed on tree branch at edge of organic peach orchard.
Visit to Cosumnes River Preserve with @justplainpeg
Visit to Sacramento National Wildlife Refuge with @justplainpeg
Visit to Cosumnes River Preserve with @justplainpeg
Duplicates are a test between photo editing on a phone or old computer
The big green eyes are perhaps a distinguishing feature, though they so match the background that I didn't even notice them when I was taking the picture.