The forewings are marked with yellow to orange, longitudinal and oblique striae, often bordered by gray or black.

The maxillary palpi are the most reduced among Gracillariidae, being barely evident as vestigial, non-segmented lobes at the base of the elongate proboscis.

Sapfeeding instars create a long serpentine, subepidermal mine on either the upper or lower surfaces of the host leaf.

In contrast to the conservative morphology of the larval and adult stages, the pupae of Phyllocnistis are structurally diverse, particularly with regard to the development of the frontal process (cocoon-cutter) of the head.

In addition, the mid-dorsal areas of abdominal terga 3–7 possess a mostly symmetrical cluster of recurved spines that frequently differ in their arrangement and form among species.