Oak leaves in Illinois are showing small, irregular white spots. These are generally caused by piercing sucking insects living on the leaf underside and removing the sap, including the green chlorophyll, from groups of cells. The genus Erythroneura contains many species of small leafhoppers that specialize on oaks.
Many species are green, but others are whitish.
They may have red or other colored markings on the back. The nymphs are also greenish or whitish, depending on the species, are wingless, and are smaller than the adults. Both nymphs and adults move sideways, typically crawling to the opposite side of the leaf or stem when disturbed. Lacebugs are also numerous on oak and cause white spots by sucking the sap out of the leaves. Their lacelike, white wings have brown markings and lie flat across the back.