3.  Pit Scales
During the summer or early fall, leaves turn brown and twigs or branches die back. Dead leaves usually remain attached to the branches throughout the winter. In the spring, new leaves may appear 3 weeks late on infested deciduous oaks. Repeated heavy infestations often kill young trees. Small (1/12 inch), somewhat flattened, green, golden, or brown scaly bumps cluster on the twigs and branches. The bark is pitted where these insects cluster.