When the leaves of many types of plants develop white spots, it is generally a sign of mealybugs. The small insects resemble white spots on plants. Mealybugs damage plants including red maple trees but can be controlled with insecticides.
The red maple is a member of the Acer family and found in the eastern United States. The fast-growing deciduous tree can be recognized by its bright red pyramidal leaves. Like many trees, it is susceptible to pests like mealybugs. The insects are tiny soft-bodied flat organisms that are covered in white wax. They resemble white spots on leaves. Large colonies of mealybugs resemble cotton.
Mealybugs use their piercing mouths to suck the sap out of leaves, depriving the plant of nutrients. They also leave a sticky residue that is a breeding ground for the fungal disease black mold.
Mealybug insecticides available to home gardeners include natural and chemical insecticides. Look for horticultural oils that contain neem oil to suffocate mealybugs. If you prefer chemical insecticides, look for products that contain permethrin or pyrethrin as the active ingredient.