Appearance and Life Cycle
In the prairies, the ash plant bug completes two generations during a growing season. The plant bug overwinters in the egg stage with nymphs first emerging in mid-May just as the ash leaves begin to unfold. The nymphs are small, oval shaped and vary from yellowish-green to dark brown. Adults measure 4 to 5 millimetres (mm) in length, 1.5 to 2.0 mm in width, and range from light green to black. First generation adults are found from early to late June while second generation adults are present and laying overwintering eggs from early August to late September.
The ash plant bug causes damage to the host by inserting its mouthparts into the leaf tissue and sucking out the plant sap. Damage by the plant bug is cumulative throughout the year, so that a light infestation in the spring may result in severe damage by the fall. Damage ranges from a yellow stippling on the upper leaf surfaces to wilted and deformed leaves, resulting in premature leaf drop, and reduced annual growth. This elusive insect is often difficult to find, but an indication of an infestation is the varnish-like black excrement spots which remain on the damaged leaves.
During a severe infestation, the following insecticides may be used: carbaryl, deltamethrin, diazinon or dimethoate. Spraying should be done in mid May to early June and again in mid July to early August to control adults prior to the egg-laying period.