Manually remove and destroy larvae in light infestations. For heavy infestations, spray with hort oil if larvae are small. Use a residual insecticide if you don't catch this pest until the larvae are large. A second generation will occur with larvae hatching in October. Locust leafminer is the leafmining beetle that devastates black locust along the highway, leaving trees with a scorched appearance.
Most trees survive the unsightly damage.
But locust leafminer can also infest yellowwood, Japanese pagoda tree and golden chain tree. Look for second generation adults feeding now and control with Orthene. New larvae should begin developing in blotch mines in July. Merit can control feeding larvae. Cooperative Extension Education in Agriculture and Home Economics, University of Delaware, Delaware State University and the United States Department of Agriculture cooperating.