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Resplendent shield bearers

March 25, 2002|By Eric T. Natwick, Imperial County-University of California Cooperative Extension adviser

"What are those seed-like things hanging from spider webs from my trees?" the lady asked.

First of all, what she saw were not seeds and they were not hanging from spider webs. What she saw was the last instar larva of resplendent shield bearer, Coptodisca splendoriferella, wrapped in leaf tissue, hanging from a silk thread it exuded.

The shield bearer larvae live as leafminers within leaves of apple, cherry and poplar trees such as cottonwood. When the larva matures, it cuts out shield-shaped portions in the upper and lower surface of the leaf mine and attaches them to itself with silk thread, forming a case.

The shield-bearing larva then attaches a silk thread to the leaf and lowers itself to the ground. When the shield-bearing larvae reach the ground they find shelter such as leaf litter or soil cracks to spend the winter. The larva pupates in the spring and emerges as a minute moth.


The forewings of resplendent shield bearer moths are lead gray on the basal half and golden with streaks of dark brown and silver at the tip. The females lay eggs singly within leaves.

After hatching early in the spring, the caterpillar bores into the leaf. As the larva feeds within the leaf it forms a tiny blotch mine between the upper and lower surface of the leaf measuring no more than one-quarter inch in diameter. The larvae actively mine cotton wood leaves in the Imperial Valley from February into May.

The resplendent shield bearer caterpillars cause minor foliar damage to apple and cherry trees but can temporarily ruin the appearance of poplar trees, especially cottonwood trees.

As if mined leaves are not bad enough, larvae get the urge to cut both surfaces of the leaf in late spring to early summer. Leaves soon have many small, oval-shaped, shot-sized holes formed when the shield bearer larvae cut both surfaces of the leaves to build their shields. Heavily damaged leaves may prematurely drop from trees.

Sprays applied for other foliar pests have controlled this pest. If you choose to use a pesticide to control the resplendent shield bearer, read and follow the label instructions. Treat when moths are present in the spring to prevent leaf infestation.

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