Though lace bugs are found on the bottom of leaves, the symptoms will become apparent on top. Damage appears as a stippling effect from white to yellow spots. From a distance, the oak leaves often appear bronze. Even if you don't find living specimens, their presence is given away by small, shiny dark spots of excrement on the undersides of leaves.
Lace bugs do not cause significant damage to oaks this late in the season, and control measures are not recommended. (Ward Upham)