Phyllonorycter insignis is a moth of the Gracillariidae family. It is known from California and Maine in the United States. The wingspan is about 9 mm. The larvae feed on Erechtites species and Ceanothus integerrimus. They mine the leaves of their host plant. The mine is found on the underside of the leaf, occupying a comparatively small area in which the leaf substance is almost entirely eaten out. The lower epidermis is closely wrinkled at maturity.