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Ash Plant Bugs


  • Larvae: Larvae grown into wingless nymphs which are green with black spots. The nymphs feed on the undersides of ash leaves for a period of 5 weeks until they become adults.
  • Adult: Adults appear in May/June and again in late summer. Adults are oval shaped, 6 mm long. They may be pale yellow to brown or black with pink markings on their backs.

Identifying infestations:

  • Deformed or yellow leaves: The bug injects a toxic saliva into ash trees that it feeds upon. Affected leaves may be deformed, twisted, or smaller in size than other leaves. The underside of damaged leaves show dark fecal spots scattered among yellow stipples. Soon the leaves turn yellow to white and eventually brown and drop from the ash tree. Affected leaves will drop from the limb if you shake the branch.

IPM Toolkit:

  • Preventive tools: Not applicable
  • Physical tools:
    • Spray infected mature trees with a jet of water in the spring to dislodge nymphs.
    • Shake the limbs of small/young trees in the spring to dislodge nymphs.
  • Biological tools: Not applicable
  • Chemical tools:
    • During the growing season, apply horticultural oils or insecticidal soaps to protect your ash tree.
    • In late winter, apply dormant oils to kill eggs over wintering on buds, twigs and bark.