I agree, thrips. Look at the underside of many leaves with a magnifier, and blow on the leaf a little. If it's thrips, you'll see them move quickly, and they usually bunch and move together. They're smaller than mites, but move very quickly. I just had them and my damaged looked just like yours. I sprayed with a light dose of azamax, they seem to be gone but I'm gonna spray a little Dr. Doom in 3 days, then another azamax spray 3 days after that. That should show 'em...