I think this is spider mite damage on a few older lower leaves of ghouse avocados.
Under microscope’s 40X power, I can see clear bodies on underside of leaf …although not the actual insects.
Just sprayed with Stylet horticultural oil ( 1.5TBS/gal) on top and bottom of leaves.
I think my diagnosis is right since spider mites are the bane of ghouse growing. Anyone have a different diagnosis or treatment? Only older leaves affected. New reddish leaves look good.