Maple Leaf Parasites

Aphids

• Aphids are small, pear-shaped insects that appear in great clusters on the undersides of leaves. They range in color from green to yellow, pink and even black. Aphids pierce the tissues of tender leaves and suck the juices out, causing leaf drop but little long-term damage in established maples. Aphids can be treated if they are problematic using foliar sprays such as pyrethrin or neem when they are seen actively feeding. Reapply treatment weekly until the aphids are eliminated.

Scale

• Scale are often misidentified as parts of plants or unusual growths or fungi. They are, in fact, insects that are basically immobile. Armored scale often resemble barnacles, though soft scale are more insect-like. Neither has a segmented body, making identification sometimes difficult. Often they are identified when crawlers appear or adults begin secreting waxy or cottony material. Scale infestation is easiest to treat with a systemic insecticide, since they feed using piercing mouthparts. Imidacloprid can be applied to the root area of affected trees during late winter or early spring. Water the application thoroughly to encourage the tree to take the insecticide into its system.

Galls

• Galls are obvious leaf deformations caused by mites that feed on maple leaves. A variety of gall-causing mites affect maple trees. The insects irritate the leaf surface until the stimulation causes the plant to surround the mites with a protective tissue layer. The gall insect then spends the rest of its life housed in or near that gall, laying its eggs inside before it dies.

Treating Galls

• Galls cannot be treated because they are tissue formations and not parasites themselves. Treatment is generally discouraged since gall mites rarely cause actual damage to maple trees. Instead, it is recommended that you trim off gall-affected tissues, rake up any fallen leaves and burn all the debris. Gall mites are carried by birds, on the wind and by people from tree to tree.