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Corythucha spp.

Corythucha cydoniae, hawthorn lace bug, on Aronia spp. Photo: Tawny Simisky
Scientific Name: 
Corythucha spp.
Common Name: 
Lace Bugs
Growing Degree Days (GDD's): 
239–363 GDD's and again 1266–1544 GDD's, Base 50F, March 1st Start Date (Source: Cornell Cooperative Extension.)
Host Plant(s) Common Name (Scientific Name): 
Alder (Alnus spp.) (Corythucha pergandei)
Basswood (Tilia spp.) (Corythucha marmorata, but also Gargaphia tiliae)
Beech (Fagus spp.) (Corythucha pallipes)
Birch (Betula spp.) (Corythucha pallipes and C. pergandei)
Butternut (Juglans cinerea) (Corythucha juglandis)
Cherry (Prunus spp.) (Corythucha pruni and C. associata)
Chokeberry (Aronia spp.) (Corythucha cydoniae in New England)
Cotoneaster spp. (Corythucha cydoniae)
Crabapple (Malus spp.) (Corythucha pergandei)
Elm (Ulmus spp.) (Corythucha pergandei)
Firethorn (Pyracantha spp.) (Corythucha cydoniae)
Hackberry (Celtis spp.) (Corythucha celtidis)
Hawthorn (Crataegus spp.) (Corythucha cydoniae)
Maple (Acer spp.) (Corythucha pallipes)
Mountain ash (Sorbus spp.) (Corythucha pallipes)
Oak (Quercus spp.) (Corythucha arcuata)
Quince (Cydonia spp.) (Corythucha cydoniae)
Shadbush (Amelanchier spp.) (Corythucha cydoniae)
Sycamore (Platanus spp.) (Corythucha ciliata)
Walnut (Juglans spp.) (Corythucha juglandis)
Willow (Salix spp.) (Corythucha elegans and C. mollicula and C. pallipes)
Insect Description: 

Lace bugs in the genus Corythucha are pests primarily of deciduous host plants. At least 27 species of them feed on deciduous trees and shrubs. Luckily, the majority specialize on certain host plants, which helps when trying to identify these insects. Lace bugs are so named for the beautiful sculptured and lacy wings and thorax. All lace bugs in this genus overwinter as adults. They can be found on or near their host plants, in sheltered areas such as bark cracks and crevices or leaf litter below. C. pallipes or the birch lace bug overwinters in the leaf litter and other sheltered areas near its hosts (see list above). In the spring, adult females lay eggs in small groups on the lower surfaces of leaves and in the axils of leaf veins. The brown eggs are partially inserted into the leaf tissue. 5 nymphal (immature) instars occur over a period of 26 days before the birch lace bug matures to adulthood. These adults may be found in New England from mid-July through mid-September. Two generations of birch lace bugs can occur per year.

C. cydoniae or the hawthorn lace bug is found throughout much of the US and Canada and northern Mexico. Rosaceous host plants are favored (see above). One or more generations may occur per year, depending upon local climates. In New England states, there may be one generation per year, with development from egg to adulthood taking 5-7 weeks. In Maryland, at least 4 generations occur annually. 

The cherry lace bug (C. pruni) is primarily a northeastern species but may extend southward toward North Carolina. Prunus serotina is thought to be its only host. Adult cherry lace bugs overwinter in the leaf litter and grasses. Adults become active again in the spring at approximately the time cherry leaves are half-grown and flowers are in early bud. Females lay eggs by early May in Massachusetts. Brown eggs are laid in circular patches on the undersides of leaf blades, partially inserted into the leaf tissue. Egg hatch begins by early June and nymphs (immatures) take 4 weeks to develop. The time from egg to adulthood is approximately 7 weeks. In the northern parts of its range, there is a single generation per year of the cherry lace bug, with up to 4 generation per year in Maryland. The feeding of adult and nymphal cherry lace bugs results in a scorched appearance of cherry foliage. Feeding occurs on leaf undersides, but it most visible on the upper leaf surface. 

The sycamore lace bug (C. ciliata) is a common pest on sycamore. Adults overwinter beneath the exfoliated bark of its host and are active by the time leaves develop in the spring. Eggs are attached to the underside of host plant leaves with a brown, sticky substance, hidden within the leaf hairs. In approximately a few days, eggs hatch and nymphs (immatures) feed on the underside of sycamore leaves. Nymphs are spiny and black and look very different from the adults. It takes approximately 30 days to go from egg to adulthood. Two or more generations occur annually, but in Maryland there may be up to 5. By late summer, all life stages may be present on the leaf undersides of sycamore, including black, tar-like excrement. This species has also been collected from ash and hickory in the southern part of its range. 

Damage to Host: 

Lace bugs feed with piercing-sucking mouthparts on the undersides of the leaves of their specific hosts. This leads to the upper surface of leaves appearing chlorotic (whitish-yellow flecks called stipples) while the undersides have brown or black varnish-like spots of excrement. Excessive feeding damage gives the foliage a bleached appearance. Stippling can coalesce, and some plants will have leaves that turn yellow and then brown. In these cases of heavy infestation, plant dieback can occur. Shrubs in full sun may be more severely damaged, and in some cases may die. Trees rarely die from lace bug feeding. 


Beginning in the spring (early May), search the upper surfaces of host plant leaves for white or chlorotic stippling. Search plants growing on sunny and dry sites first, as they may be the first to develop a lace bug infestation. Older leaves may exhibit damage first. If damage is seen on the upper leaf surface, flip leaves over and look for lace bug nymphs and adults, as well as the tar-like and circular spots of excrement. 

Cultural Management: 

Do not plant lace bug-prone hosts in sunny locations. Select sun-tolerant trees and shrubs that are not lace bug hosts.

Natural Enemies & Biological Control: 

Natural enemies of Corythucha spp. lace bugs exist. The sycamore lace bug is known to have predators including but not limited to: lacewings, assassin bugs, minute pirate bugs, spiders, and predaceous mites. In North Carolina, historically, up to 1/4 of the sycamore lace bug eggs may be non-viable. Johnson and Lyon (1991) suggest that there is an unknown mortality factor reducing sycamore lace bug egg viability in that part of the insect's range. However, for most lace bug species, natural enemies are not thought to reduce populations below damaging levels in managed landscapes. Other predators and pathogens of lace bugs in this genus have been studied (Invasive Species Compendium; CABI).

Chemical Management: 

Abamectin (NL)

Acephate (NL)

Azadirachtin (NL)

Beauveria bassiana (NL)

Bifenthrin (NL)

Carbaryl (L)

Chlorantraniliprole (NL)

Chlorpyrifos (N)

Clothianidin (NL)

Cyfluthrin (NL)

Deltamethrin (L)

Dinotefuran (NL)

Fenpropathrin (NL)

Flonicamid+cyclaniliprole (N)

Gamma-cyhalothrin (L)

Horticultural oil (L)

Imidacloprid (L)

Insecticidal soap (NL)

Lambda-cyhalothrin (L)

Malathion (L)

Permethrin (L)

Pyrethrin+sulfur (NL)

Spinetoram+sulfoxaflor (N)


Chemical management sprays should be concentrated on leaf undersides.

When used in nursery settings, chlorpyrifos is for quarantine use only.

Active ingredients that may be applied systemically include: Abamectin (injected), acephate (injection), azadirachtin (injection, soil drench), chlorantraniliprole (soil drench), clothianidin (soil drench), cyantraniliprole (NL), dinotefuran (soil drench), and imidacloprid (soil drench).

Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.

Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.

Read and follow all label instructions for safety and proper use. If this guide contradicts language on the label, follow the most up-to-date instructions on the product label. Always confirm that the site you wish to treat and the pest you wish to manage are on the label before using any pesticide. Read the full disclaimer. Active ingredients labeled "L" indicate some products containing the active ingredient are labeled for landscape uses on trees or shrubs. Active ingredients labeled "N" indicate some products containing the active ingredient are labeled for use in nurseries. Always confirm allowable uses on product labels. This active ingredient list is based on what was registered for use in Massachusetts at the time of publication. This information changes rapidly and may not be up to date. If you are viewing this information from another state, check with your local Extension Service and State Pesticide Program for local uses and regulations. Active ingredient lists were last updated: January 2024. To check current product registrations in Massachusetts, please visit: .