Abstract: An important invasive insect pest, locust gall midge Obolodiplosis robiniae (Haldemann) (Diptera: Cecidomyiidae), was newly discovered from China. Native to North America, this species attacks leaf of black locust tree, Robinia pseudoacacia L. As one characteristic of infestation, its larvae (usually 3-8 individuals) gregariously feed inside the longitudinal rolling gall along the edges of leaf. In Qinhuangdao City of Hebei Province and Jinzhou, Anshan, Huludao and Chaoyang cities of Liaoning Province, its attacking rate on black locust trees were about 100%. The pest threats the health of R. pseudoacacia which has been planted in large areas in China. Strict quarantine, study on its biology and control measures are necessary in order to block its spread and damages.

Key words: Invasive pest, Obolodiplosis robiniae, morphology, China