Camptomyia is a genus of gall midges belonging to subfamily Porricondilinae. On the study of shiitake mushroom farm in Korea, three species of maggots were collected. Among them, two Camptomyia spp. were recognized as the major pests. Colonies of these maggots were feeding on the mycelium of shiitake mushroom, disturbing the formation of mushroom fruit body. The morphology of C. heterobia and C. corticalis were illustrated with the description.