Honeylocust Plant Bug
Honeylocust plant bug, Diaphnocoris chlorionis, causes damage when the insect’s mouthparts penetrate the leaf cells and injects a toxic saliva while feeding. This toxic saliva, which helps with the uptake of plant cell contents and digestion, kills cells around the feeding site causing browning, leaf rolling, distortion, and chlorosis. Damage can weaken the tree, causing it to be more susceptible to attack by secondary insects and diseases. After the plant bugs are gone, the damaged leaves will remain on the plant for the rest of the season.
Trees at Risk
Signs of Damage
- Yellowish-white leaf stippling on upper surfaces that eventually turns brown.
- Leaf distortion and chlorosis.
- Chlorotic spots turn brown, and the entire leaf dries and drops.
- Severe infestations may lead to complete defoliation, but death rarely occurs.
- Adults are pale green and about 3/16 inch long with four segmented antennae and a beak-shaped mouthpart.
- The nymph looks just like the adult, but smaller.
- Both adults and nymphs are very active and can be seen flying when tree branches are disturbed.
- Eggs are light in color and nearly 1/8 inch in length.
- Just after bud break in early spring, young nymphs crawl into unfolding leaves and begin feeding.
- Nymphs feed for 3-4 weeks before maturing.
- Adults mate and lay eggs.
- Eggs overwinter by becoming embedded in the bark.
In early spring, newly emerging leaves should be examined for active nymphs, stippling, and distortion symptoms prior to treatment. If nymphs are present, insecticides should target young nymphs 7 to 10 days after bud break. If using contact sprays, be sure to cover the foliage and bark completely.