Top of leaves appear white, were mostly white last fall.  Insect on underside, resembles rice to me.    See pictures

Hello, happy to help.

They appear to be either leafhoppers or treehoppers but the photo of the back of the leaf isn't very clear. You haven't said how extensive the leaf damage is in the tree's canopy but if it's just a few leaves, they're not likely to hurt your tree. Just be sure it gets an inch of water each week. Set out a rain gauge to help you determine if watering is needed and be sure to water well outside the dripline of the tree since its roots extend quite far.

If you think the damage is extensive, I recommend contacting a certified arborist to evaluate your tree for other signs of stress and to devise a plan of action. Here is a link to information about how to find and hire a professional.

Good-luck!