Phyllonorycter diaphanella is a moth of the Gracillariidae family. It is known from Texas and Ohio in the United States. The wingspan is about 6 mm. The larvae feed on Quercus species, including Quercus bicolor and Quercus ilicifolia. They mine the leaves of their host plant. The mine has the form of a blotch mine on the underside of the leaf. The epidermis is wrinkled, so that the leaf is slightly bent. The parenchyma is entirely consumed, and the mine is transparent