Madrone Shield Bearer: Appearance, Territory, Damage and Life Cycle

Latin Name: Coptodisca Arbutiella

Appearance: Coptodisca Arbutiella is a Heliozelidae moth that is also known as the madrone shield bearer. In 1904, August Busck characterized it. It may be found in western North America from California to British Columbia. The larvae eat the leaves of Arbutus species. They feed on the nutrients in their host plant’s leaves. The mine has a blotchy appearance. Pupation takes place in elliptical casings excavated from the top and lower leaf surfaces by fully developed larvae.

Hosts Plants: Species are host specific, with at least 17 angiosperm families being used.

Territory: North America from California to British Columbia.

Damage Insect Cause: A tiny moth, the serpentine madrone miner is an adult. The larvae of this leaf- and twig-mining insect build sinuous, serpentine mines beneath the leaves. Individual leaf loss is unsightly, but it has minimal impact on the tree’s long-term health. Throughout its habitat, this moth has an influence on madrone. The madrone shield carrier develops little dark spots on the upper leaf surface. When the larvae are ready to pupate, they cut two oval portions of leaf (upper and below leaf surface), sew them together with silk, and carry this case to a safe place to pupate. These two insects are often seen in tiny numbers. Occasionally, there is a population spike that, owing to natural constraints, fades by the next day.

Life History and Habits: Last instar larvae build a portable case by cutting disks from the top and lower epidermis and stitching them together with silk, thus the common name “shield bearers.” The abandoned mines, with their unmistakable “shot holes,” are remarkable. Leafminers are often found in small numbers among the trees. Typically, only a few mines are discovered. If infected leaves are irritating, remove them; otherwise, allow small flaws that do not affect the tree.