Maple Tree Pests

Although maple trees are some of the most beautiful trees in the forest and in your backyard, they are also suspect to a wide variety of insects and pests that can cause serious damage if not properly identified and controlled. The following are some of the more common pests associated with maple trees in North America.

Maple Spindlegall and Bladder Gall Mites

These maple pests are usually invisible to the naked eye; however, the spindle-shaped galls they leave on the surfaces of maple leaves are easily identifiable. They feed on a wide variety of maple trees, including sugar, silver, and red, although they usually do not cause significant damage to healthy trees. Furthermore, control is usually minimally effective.

Clearwing Borers

These maple pests usually appear as wasp-like insects that are 12-19 mm long and may sometimes exhibit different colors depending on the sex. The larvae devour the sapwood of trees during the summer, although the adults do not cause damage, as they live for only a few days. There are a number of control methods available. Cultural control involves minimizing damage to trees, while chemical control often entails spraying the tree with a long-lasting insecticide approximately ten days after discovering the first insect. A number of natural controls are also available, such as the numerous species of parasitic wasps that prey on these insects.

Maple Velvet Erineum Gall Mite

These maple pests infect a wide variety of maple trees as well as other woody trees such as beech. They are very small, so they require a dissecting microscope to see clearly. The females feed on leaves, causing them to create felt patches, in which the insects then reproduce. The patches can be red, bright crimson, or green and can appear on both the upper and lower surfaces of leaves. The damage caused is typically aesthetic, and control can be very difficult. Carbaryl is a conventional pesticide that sometimes proves effective.

Cottony Maple Scale

The cottony maple scale inhabits a wide variety of maples, especially focusing on silver maples. As they are very small, detection typically relies on identifying the long, cottony egg sac produced by the females. They produce one generation per year, and the larvae move along the leaves and veins, typically on the underside. They produce honeydew, a substance that can also lead to the growth of sooty mold, and they can also produce leaf yellowing and die back of twigs and branches. Pesticides are only effective if you target the insect during the crawler stage.

Sources

University of Minnesota Extension; Pests of Trees and Shrubs.