Browning of Locust Leaves
While driving along I-77 from Fairfield through Chester counties, it is hard not to notice the honeylocust leaves turning brown. While this may look like fall leaf change, this is actually due to the feeding of the Locust Leafminer (Odontota dorsalis (Thunberg)). These leaf beetles prefer to feed on black locust and honeylocust, but they will occasionally attack apple, beech, birch, cherry, elm, oak, and hawthorn.
Adult beetles overwinter in bark crevices or in leaf litter and begin feeding in the late spring; they feed on the lower side of the leaves and skeletonize the leaves (only the leaf veins are left) or chew small holes in the leaves. Eggs are laid on the undersides of the leaves. The larvae create mines (tunnels) between the top and bottom leaf layers, which is where they feed. Eventually, the larval feeding causes the leaf to dry and turn a rusty-brown color. The brown leaves will remain on the tree for some time, giving an off-color to the trees. The larvae pupate in the leaf mines and emerge as adults in mid-summer. There are two generations of beetles per year.
The adult beetle feeding has little affect on the tree health. However, the mining by the larva can cause growth loss or death in trees under stress. Typically, parasites and predators will reduce the leafminer populations and chemical control rarely is warranted.
For more information, please contact Laurie Reid at (803) 667-1002 or via email firstname.lastname@example.org