NC State Extension Publications

Description and Biology

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The chrysanthemum lace bug, Corythuca marmorata, is an occasional pest of chrysanthemums where these small (1/8 inch long), lacy adults and tiny, spiny nymphs feed on upper and lower surfaces of leaves. Mature bugs have black bodies with yellowish antennae and legs. The feet are brownish. The top has a noticeably inflated thorax (the hood), and the wings and hood are covered by small, transparent cells that resemble lace.The wings have four irregular smoky-brown bands although these markings are variable. The markings of males are usually more intense. Females insert their tiny, dark brown eggs into the leaf until only the conical, yellowish cap is visible. Eggs are usually placed along the larger veins in groups of 4 to 75, and the eggs are covered by a dark brown varnish-like excretion. From the eggs hatch minute nymphs that develop through five stages before finally molting to the adult stage. Nymphs often cluster together in groups of 6 to 100. These lace bugs overwinter in dry leaves, under stones, in grass clumps, and other sheltered debris.

chrysanthemum lace bug

Adult chrysanthemum lace bugs are usually whitish with brown markings.

chrysanthemum lace bugs

These chrysanthemum lace bugs are about as pale as they get.

Host Plants

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Chrysanthemum lace bugs are sometimes noticeably abundant on mums, asters, golden rod, ragwood, sunflower and other plants in the aster family. When abundant, chrysanthemum lace bugs cause noticeable to severe, pale speckling on leaves.

Residential Recommendations

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If they are like other lace bugs in the landscape, chrysanthemum lace bug eggs are plagued by tiny parasitic wasps. Predaceous bugs may also reduce populations. However, these natural control agents may fail to prevent noticeable damage. Lace bugs can be relatively difficult to control. Perhaps this is because the eggs are inserted into the leaf tissue and covered with a drop of varnish-like excrement and are thereby protected from insecticides. It is a good idea to monitor mums for the first signs of damage. Orthene is relatively effective for lace bug control, but it is somewhat harsh on predators and parasites. Insecticidal soaps and horticultural oils are toxic to nymphs and adults, but they do not kill eggs nor do they provide any residual control (and thus are safer for parasites and predators). Safari and imidacloprid are systemic insecticides that can be applied to the soil surface to kill the lace bugs above. Chrysanthemum lace bugs should be susceptible to most contact pesticides labeled for landscape use.

Other Resources

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For assistance with a specific problem, contact your local Cooperative Extension center.

This factsheet has not been peer reviewed.

Author

Professor Emeritus
Entomology & Plant Pathology

Publication date: Dec. 16, 2019
Revised: Dec. 16, 2019

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