Lace bugs
Click for larger image White flecking on upper leaf surface on azalea (Rhododendron) caused by feeding of lace bugs (Hemiptera); heavy infestation

There are approximately 140 North American species of lace bugs. Most have a specific host preference, which aids in identification. Some of the important species of lace bugs are for the azalea - Stephanitis pyrioides, hawthorn - Corythucha cydoniae, lantana - Teleonemia scrupulosa, and hackberry - C. celtidis. Lace bugs also feed on oak, elm, basswood, fringetree, and pyracantha among others.

The different species of adults vary from 1/8 to 3/8 inch in length but all have wings and thorax beautifully sculptured with an intricate pattern of veins that resembles lace. The nymphs are dark and are pointed at both ends. Lace bugs, both immature and adults, are most often found on the underside of leaves.

The London plane tree, Platanus acerifolia, is more susceptible to the lace bug than the sycamore, Plantanus occidentalis; both are hosts to the same species of lace bug.

Symptoms and Diagnosis

If heavily infested, the leaves may turn yellow and fall from trees and shrubs. The lace bug feeding mechanism is one that pierces and sucks the plant juices from leaves. This leaves tiny chlorotic flecks on the upper leaf surface. The underside of the leaves will have adults and spiny, dark-colored nymphs. The underside of leaves will look dirty with dark-brown spots and stains. When disturbed, lace bugs exhibit a peculiar bouncing movement.

Life Cycle

Female lace bugs lay groups of eggs on the underside of leaves most often along the midrib. These eggs are partially inserted into the leaf tissue and are pale and almost completely hidden inside the leaf. Many species secrete a brownish substance that hardens over the eggs and secures them to the leaf. Dark spiny nymphs hatch from the eggs and go through 5 to 6 nymphal instars before reaching adulthood. A complete life cycle takes only 30 to 40 days; several generations may occur each year. Lace bugs are more prevalent in late summer and fall. In late summer, both adults and nymphs will be feeding at the same time. Some species overwinter as eggs in the leaf or bark crevices or similar protected areas while other species overwinter in the adult stage.

Integrated Pest Management Strategies

1. Live with the insects but maintain plant vigor. In many cases, the damage occurs late enough in the season or is minor enough not to require action. Keeping plants healthy by watering during periods of drought will limit any damage caused by the insects.

2. Select planting areas carefully. Plant susceptible species away from sidewalks and lawns as dropping leaves, twigs, and lace bug excrement can be bad enough to be considered unpleasant.

3. Spray with water. Nymphs can be dislodged by forceful sprays of water and are vulnerable to control by contact with insecticidal soaps.

4. Sanitation. Prompt removal of leaves and twigs under plants can remove overwintering pests and limit the chances of reinfestation.

5. Control. Natural enemies are usually effective in maintaining populations at a low level and bringing outbreaks under control. Chemical controls are usually only used on shade and ornamental trees. Control of the azalea lace bug on evergreen azaleas is often required as the loss of leaves on these plants can have a more serious impact on plant health.

6. Use insecticides. Pesticides registered for use include acephate (Orthene), bendiocarb (Turcam, Closure), capsaicin, carbaryl (Sevin), disulfoton (Di-syston), malathion, permethrin, pyrethrins, and horticultural oils. Spray as soon as eggs hatch on leaves in early spring. Some control is possible with a dormant spray applied just before growth in spring.

Organic Strategies

Strategies 1, 2, 4, and the use of natural enemies in Strategy 5 are strictly organic approaches. For an organic approach to Strategy 6, consult the Organic Materials Review Institute (OMRI™) for appropriate pyrethrin products.

More images:

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Lace bug (Hemiptera) and typical black tarry feces on underside of sycamore leaf (Platanus)
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Tiny necrotic flecks on sycamore leaf (Platanus) typical of lace bug feeding (Hemiptera); heavy feeding gives the leaves an overall bleached or yellowed appearance
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Close-up of lace bug (Hemiptera) on sycamore (Platanus); note dark, varnish-like excrement, a characteristic of lace bugs
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Close-up of lace bugs (Hemiptera)--adult left, nymph right--on sycamore (Platanus); note dark, varnish-like excrement, a characteristic of lace bugs
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Underside of sycamore (Platanus) leaf showing lace bugs (Hemiptera); adults are silvery white, nymphs are dark, and excrement is dark dots
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White flecking on upper leaf surface on azalea (Rhododendron) caused by feeding of lace bugs (Hemiptera); light infestation
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Heavy infestation of lace bugs (Hemiptera) on underside of azalea (Rhododendron) leaves; silvery white adults, dark nymphs, dark spots of excrement
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The bronze coloration of the leaves on this hawthorn (Crataegus) was caused by lace bug (Hemiptera) feeding
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Oak lace bug (Hemiptera ) damage to bur oak (Quercus macrocarpa) leaves
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Underside of bur oak leaf (Quercus macrocarpa) with dark excrement of oak lace bugs scattered randomly & two white lacewing eggs (Neuroptera) suspended over cluster of lace bug eggs (Hemiptera )
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Adult oak lace bug (Hemiptera ) on underside of bur oak leaf (Quercus macrocarpa)
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Close-up of oak lace bug eggs (Hemiptera ) on underside of bur oak leaf (Quercus macrocarpa)