Madrona shield bearer (Coptodisca arbutiella)
Serpentine madrona miner (Marmara arbutiella)
Description, biology and damage The serpentine madrona miner adult is a tiny moth. Larvae of this leaf- and twig-mining moth blaze sinuous, serpentine mines across the surface of leaves. Although damage might be unsightly on individual leaves, they do not affect the long-term health of the tree. This moth affects madrone throughout its range. The madrona shield bearer forms small dark areas on the upper leaf surface. When ready to pupate, the larvae cut two oval pieces of leaves (upper and lower leaf surface), stitches them together with silk, and moves with this case to a protected location and pupates within. These two insects generally occur in low numbers. Occasionally there is a flare-up in the population which crashes by the next season due to natural controls.
Pest monitoring Leafminers usually are scattered in low numbers throughout the trees. Usually, only a few mines can be found.
Remove infested leaves as they are seen if they are bothersome; or tolerate minor blemishes which do not harm the tree.
See Table 3 in: