We often associate lace bugs with sycamores and cotoneaster, but oaks can be affected as well. Actually, the lace bugs that affect these three plants are separate species. Lace bugs are true bugs and therefore feed by sucking sap through straw-like mouthparts that pierce the leaf. These three species also are similar in appearance due to the lacy quality of the wings that lie flat over the back.
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 normally do not cause significant damage to oaks, and control measures are usually not recommended. However, contact insecticides can be used for control in extreme cases. Direct the spray under the leaf where the lace bugs feed. (Ward Upham)