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September 1, 2004

Lacebugs are becoming numerous on sycamore and oak. They also may be common on walnut, rhododendron, and azalea. Damage appears on these plants as light areas on the leaf uppersides. Close examination reveals that the damage consists of many tiny light spots corresponding to cells or groups of cells where the cell contents have been sucked out by the lacebugs. Heavily infested leaves, particularly oak leaves, curl downwards from the edges. On hackberry, high numbers of lacebugs cause the leaves to turn yellow and fall. Although typically a wide variety of woody plants are attacked, a sample of purple dome aster submitted to the Plant Clinic this year was found to be heavily infested with lacebugs. They had caused the leaves to turn brown.

The undersides of attacked leaves have large amounts of the lacebugs’ fecal matter, which appears as tarry, black dots. The bugs themselves are 1/8-inch-long, flattopped insects. The wings and other upper portions of the body are white and brown to black, appearing lacelike. Nymphs are smaller than the adults, blackish, somewhat diamond-shaped, and also flattened on top. They hatch from slender black eggs that stand on end in loose clusters on the leaf undersides.

Lacebugs rarely cause enough damage to warrant control efforts, although they have been linked to dieback of hackberry and aster. Acephate (Orthene), carbaryl (Sevin), cyfluthrin (Tempo), insecticidal soap, and other insecticides are effective control agents.

Author: Phil Nixon


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