In a large tree, controlling scale chemically is not always practical. The size of the tree, the need for specialized equipment and the cost may prohibit this approach. Oil sprays should be applied as a dormant treatment in spring or fall. Apply other materials when crawlers appear and repeat in 10 days. As with all pesticides, read and follow all label instructions and precautions.
Maples often develop irregular growths or swellings known as galls on their leaves.
Each insect or mite produces its own distinctive gall shape. Often the distinctive shape allows for identification of the pest. Galls typically develop in spring at about the time that leaves are expanding. Once the gall forms, the pest is protected inside the structure. When homeowners see these growths on the leaves of their maples, they often become quite concerned.