Ash plant bug

Nuisance Type:

Plants Affected:

Images of This Insect:

Ash plant bug damage. (photo: Jeff Hahn.

Adult ash plant bug. (photo: Whitney Cranshaw, Colorado State University)

Ash plant bug nymphs and leaf damage. (photo: James Solomon, University of Georgia)

Ash Plant Bug-A common sap feeding insect pest that attacks both green and white ash trees.


Adult Ash plant bugs appear in late June or early July.  They are 1/4 inch long, slender bugs that are green to light brown in color and have a distinctive yellow triangular spot in the middle of the back.  Nymphs are tiny, active, and light green to black in color.

Life Cycle

These insects overwinter as eggs on the bark of trees.  The eggs begin to hatch as the buds break and the foliage emerges in the spring.  Tiny green nymphs crawl to the undersides of leaves and begin a feeding period that lasts approximately five weeks.  New adults then lay eggs for a second generation of nymphs that feed during the second half of the summer.


Puncture wounds produced by the feeding action of the bugs cause discrete white speckles on the upper surface of the leaves.  Individual speckles eventually coalesce into broad chlorotic areas on heavily infested trees, which may turn brown and the leaves may drop prematurely.  The undersurface of infested leaves are marked with shiny black specks of excrement called varnish spots.


Control of the ash plant bug is seldom warranted.  Foliage lost because of damage from this bug is easily replaced by healthy, vigorous trees.  Also, by the time damage is noticed it is usually too late for effective control.  The best management for ash plant bug is to maintain tree health and vigor through watering and mulching.

If you have stressed or newly transplanted trees, insecticides can be used.  Timely treatment while the nymphs are still small can prevent feeding damage symptoms.  Begin checking ash tree foliage for nymphs at the time redbud trees in your neighborhood are beginning to bloom.