Most Common U.S. Tree Pests

A Guide to Insect and Disease Pests of the Forest

Juvenile and adult aphids, aphid eggs, and moulting individual on Helleborus niger. (Michel Vuijlsteke/Wikimedia Commons/CC BY-SA 3.0)

Trees in a forest or landscape are under constant attack by insects and pathogenic diseases. A tree in good health can withstand most of these pests for awhile but can be overwhelmed as site conditions and pests relentlessly rob the tree of its vigor.

The best way to prevent tree mortality is to improve conditions that support tree health. Take time to observe your trees for signs of stress - dying limbs, bleeding cankers, visible fungi, yellowing and drying of foliage.

Remember that the best way to protect a tree from pests including disease and insects is to have a healthy tree. A healthy tree starts with its first year of life.

Forest Disease Pests

The vast majority of forest and landscape diseases attack trees in the form of bacterial pathogens and fungal infections. Many will not kill a tree but can have a cumulative effect on a tree's vigor and health over time. A few will rapidly kill trees and demand that you keep a watch for symptoms.

Identification of Common Tree Disease Pests: A guide to common diseases including root rots, blights, cankers, wilts and decline. Start your review with the most often seen tree diseases in North America:

Also review "worst of the worst" tree disease pests in North America:

    Forest Insect Pests

    Insects that attack trees come in many sizes and shapes. The beetles consume leaf parts and inner bark; the aphids, leafminers, and moths defoliate; the borers consume wood; the gall-making wasps deform limbs and leaves. Not all insects will kill a tree, but the "killers" listed can be certain death when insect populations explode.

    Identification of Common Tree Insect Pests: A guide to common insects including beetles, borers, caterpillars, weevils and adelgids. Also review "worst of the worst" tree insect pests in North America:

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    Your Citation
    Nix, Steve. "Most Common U.S. Tree Pests." ThoughtCo, Apr. 3, 2017, Nix, Steve. (2017, April 3). Most Common U.S. Tree Pests. Retrieved from Nix, Steve. "Most Common U.S. Tree Pests." ThoughtCo. (accessed February 25, 2018).