The red maple tree is affected by a variety of pests and diseases.
Insects such as the leaf stock borer and petiole borer enter the leaf stock under a leaf blade, defoliating the tree. Although these insects can cause problems with maple trees, they do not cause serious injury.
Gall mites create growth on the surface of the tree's leaves. These growths are small but there can be so many of them that they cause individual leaves to curl up. Galls do not cause serious problems, however, so you don't need to control the mites with chemicals.
Aphids are a common infestation of maple trees. If your tree has too many of these insects, a problem called "leaf drop" can occur. Honeydew accumulating on lower leaves and objects underneath the tree is another sign of a large aphid infestation.
Cottony maple scale is an insect that forms a cottony mass on the under sides of branches. You can control scales with horticultural oil sprays.
Anthracnose sometimes affects maple trees during the rainy season. This disease causes brown or tan areas to form on the leaves.
Scorch is a disease that affects maple trees that have poor root systems and usually strikes during hot weather when there is a lot of wind. This disease affects maple trees that have poor root systems.