Lace bugs (order Hemiptera; family Tingidae) were a hot topic during this week’s BYGL Zoom Inservice. Although the bugs have been with us in one form or another for the entire season, their accumulated leaf damage is now very evident.
Lace bugs are so named because of the intricate, lace-like pattern of the veins and membranes in their wings, which are held flat over their body. The pronotum, which is the dorsal part of the thorax just behind the head, is commonly highly ornamented with lace-like lateral extensions that resemble flattened “shoulders.” Some species have a bulbous structure called a “hood” that rises from the pronotum and extends over the head.
A close examination of the leaves of plants infested with lace bugs will reveal the characteristic “stippling” produced by lace bugs, which consists of numerous tiny yellow spots. The symptom is named for the monochromatic art technique of shading drawings by repeatedly tapping the tip of a black pen on paper to produce numerous small dots. Speaking from personal experience, it works best if you drink a lot of coffee.
The stippling is produced by lace bug adults and immatures (nymphs) using their piercing-sucking mouthparts. They stab their mouthparts into the succulent leaf mesophyll, sandwiched between the upper and lower epidermal layers, to rupture the cells. Then they suck up the contents.
Although most species found in Ohio live on the lower leaf surface of their host plants, there are a few notable exceptions to this rule. If the feeding is done on the lower leaf surface, the stippling appears on the upper leaf surface. The opposite occurs with those species that live on the upper leaf surface. High winds and heavy rains can drive lace bugs to lower leaves, so the stippling damage may be heaviest in the lower canopy.
The stippling may at first appear as distinct 1/4 - 1/2" diameter spots on the upper leaf surface created by 1st instar nymphs feeding near the cluster of eggs from which they hatched. I first noticed this odd symptom with basswood lace bugs on silver linden owing to the dark green upper leaf surface. However, it can also be seen with other lace bugs.
With heavy infestations, the stippling will eventually coalesce to produce large white patches, causing leaves to look "bleached-out." As the damage progresses, portions of the leaf, or entire leaves, will turn yellow to copper brown.
Keep in mind that leaf discoloration may be associated with other plant maladies. For example, as shown in the picture below, the subtle whitening produced by powdery mildew on oak may be mistaken for lace bug damage and vice versa requiring more than a cursory examination.
Lace bug adults and nymphs also exude black tar-like fecal deposits. This tell-tale feature of lace bug activity adds to the unsightly appearance of heavily infested leaves.
The oval or flask-shaped eggs of most species are black, which may cause them to be confused with fecal spots. However, the fecal spots are randomly distributed while the eggs are grouped in loose clusters.
Research has shown that adults of some species actively guard their eggs and nymphs against predation. This may explain why it is common to see adult females remaining close to egg clutches. It is also common to see adult females apparently “herding” groups of nymphs.
High lace bug populations can produce enough leaf damage to cause early leaf drop, branch dieback, and even the death of small trees and shrubs. Many lace bugs in Ohio have 2 to 3 generations per season, with the leaf damage ramping up with each successive generation. The accumulated damage becomes most evident at this time of the year.
Lace bugs can also be a serious nuisance pest. They have a penchant for dropping from heavily infested trees onto unsuspecting hikers, picnickers, and patrons of outdoor bars and cafes. They don't feed on people, but they can use their piercing-sucking mouthparts to deliver a pinprick bite, particularly if they fall between a person's neck and shirt collar.
SIDE NOTE: A common error is to inadvertently call lace bugs “lacewings;” I’ve done it myself. It’s an easy mistake given that both names reference lacy wings. However, lacewing (order Neuroptera) larvae are specialized predators, so lacewings are good. I keep it straight by remembering, “Wings are good, bugs are bad.” Maybe that just works for me.
A Litany of Lace Bugs
Oak Lace Bug (Corythucha arcuata) is native to North America and is most commonly found on oaks in the white oak group, particularly white oak (Quercus alba), swamp white oak (Q. bicolor), bur oak (Q. macrocarpa), and chinkapin oak (Q. muehlenbergii). Populations tend to rise and fall dramatically from year to year, with heavy infestations causing leaves to become yellowish-white.
Oak lace bug was discovered in Italy in 2000 and has since spread throughout several European countries. Free of its natural enemies, the lace bugs are causing extensive annual damage to native European oaks. Ohio was visited this past summer by a team of entomologists from the University of Sopron in Sopron, Hungary, who searched for parasitoid wasps that may provide relief from the rampant annual ravaging of European oaks. It was interesting hearing them speak about unbridled damage to oaks growing in the Carpathian Mountains in neighboring Transylvania.
Oddly, laboratory host plant studies conducted in Europe showed that two raspberries, Rubus idaeus, a native European red raspberry, and R. ulmifolius (elmleaf blackberry or thornless blackberry), a native European blackberry that’s become naturalized in parts of the U.S., could support oak lace bugs from eggs to adults. However, I could find no references showing that these raspberries are colonized by oak lace bugs in the wild.
Be aware that Oak Spider Mites (Oligonychus bicolor) may produce similar damage. However, they feed on the upper leaf surface and tend to concentrate their stippling around leaf veins. As with all spider mites, they use their fang-like chelicerae to rupture individual leaf cells so they can ingest the contents. Thus, spider mite stippling is much smaller compared to lace bug stippling.
Other lace bugs that have produced noticeable damage this season in Ohio include basswood lace bug (Gargaphia tiliae); buckeye lace bug (C. aesculi); chrysanthemum lace bug (C. marmorata); hackberry lace bug (C. celtidis), hawthorn lace bug (C. cydoniae); sycamore lace bug (C. incurvata); and grass lace bug (Leptodictya plana) which is the oddball in this list.
The buckeye, hackberry, oak, and walnut lace bugs confine their feeding to their namesake hosts. Sycamore lace bugs may be found on American sycamore (Platanus occidentalis) and, to a lesser extent, on London planetree (Platanus x acerifolia).
Basswood lace bug grew up with American basswood (Tilia americana); however, it commonly focuses its attention on silver linden (T. tomentosa). This tough European native can handle many of the urban slings and arrows that send less hardy trees to wood chippers. However, our native lace bug may turn silver lindens into golden-brown lindens by September in the Greater Cincinnati region.
Participants in the Ohio Diagnostic Workshop held last Friday in Secrest Arboretum, Wooster, OH, were treated to samples of heavily stippled hackberry (Celtis occidentalis) leaves harboring a heavy hackberry lace bug population. The samples were collected from northwestern Ohio; however, this lace bug may be found throughout the state, causing hackberry leaves to appear rusty-brown.
Despite its common name, the hawthorn lace bug has one of the most cosmopolitan palates of any lace bug found in Ohio. It will feast on a wide variety of rosaceous plants but is most commonly found on hawthorn (Crataegus spp.), serviceberry (Amelanchier spp.), Cotoneaster spp., firethorn (Pyracantha coccinea), and occasionally on rose (Rosa spp.) and black chokeberry (Aronia melanocarpa). The lace bugs may also feed on a few plants outside of the rose family, such as common buttonbush (Cephalanthus occidentalis, family Rubiaceae).
Chrysanthemum lace bugs are unusual in that they may be found on both the lower and upper leaf surfaces. The lace bugs feed on a wide range of herbaceous perennials in the Asteraceae family, including asters, Rudbeckia, goldenrods, and sunflowers as well as weeds such as thistles. These lace bugs may occur in greenhouses as well as landscapes. Indeed, landscape infestations may originate in greenhouses.
Grass lace bugs were first described in 1913 from a specimen collected in Oklahoma. Since that time, the lace bugs have been confirmed in AL, AZ, GA, FL, KS, MS, NM, and TX. I can find no reports of the lace bug previously being found in Ohio other than a BYGL Alert that I posted in 2022:
https://bygl.osu.edu/index.php/node/2028
Despite its common name, research has shown that grass lace bugs have a somewhat narrow host range focused on grasses used as landscape ornamentals. The bugs prefer to feed on members of the Poaceae family, and the genera that are most heavily damaged include Andropogon, Schizachyrium, Festuca, Spartina, and Sorghastrum. However, plants belonging to the Pennisetum genus receive the highest level of damage, and this is the only genus that supports oviposition.
Thus, it appears that Pennisetum spp. can serve as a point source for grass lace bugs in landscape plantings. There are some very popular ornamental grasses that belong to this genus, including fountain grass (P. alopecuroides), Oriental fountain grass (P. orientale), and annual fountain grass (P. setaceum).
Too Late for Effective Management
Applications targeting lace bugs at this time of the year will have little impact on plant health or aesthetics. Eliminating the lace bugs will not reverse the accumulated leaf damage that started much earlier in the growing season. Suppressing lace bugs will provide marginal improvement to the health of deciduous trees and shrubs because they are nearing the time of the year when leaves are shed. Even Pennisetum grasses have largely finished their season by producing seedheads.
This means management efforts should focus on planning for next season, starting with closely monitoring plants that were heavily infested this season for re-development of populations next season. Keep in mind that lace bug populations commonly rise and fall dramatically from year to year, thanks to the collective impacts of predators, parasitoids, and pathogens as well as environmental conditions.
Selected References
Bernardinelli, I. and P. Zandigiacomo. (2000). First record of the oak lace bug Corythucha arcuata (Say) (Heteroptera, Tingidae) in Europe. Informatore Fitopatologico, 50(12), pp.47-49.
https://www.cabidigitallibrary.org/doi/full/10.5555/20013033814
Bernardinelli, I., (2006). Potential host plants of Corythucha arcuata (Het., Tingidae) in Europe: a laboratory study. Journal of applied entomology, 130(9‐10), pp.480-484.
https://doi.org/10.1111/j.1439-0418.2006.01098.x
Carr, E.R., S.K. Braman, and W.W. Hanna. (2011). Host plant relationships of Leptodictya plana (Hemiptera: Tingidae). Journal of Environmental Horticulture, 29(2), pp.55-59.
Carr, E.R. and S.K. Braman. (2012). Phenology, abundance, plant injury and effect of temperature on the development and survival of Leptodictya plana (Hemiptera: Tingidae) on Pennisetum spp. grasses. Journal of Entomological Science, 47(2), pp.131-138.
https://doi.org/10.18474/0749-8004-47.2.131
Paulin, M.J., Melika, G., Triapitsyn, S., Betchel, D., & Csoka, G. (2025). Erythmelus klopomor: First steps toward classical biological control of the oak lace bug Corythucha arcuata, a dangerous invader in the European oak forests. Preprint, Research Square
https://doi.org/10.21203/rs.3.rs-5795762/v1
Paulin, M., Hirka, A., Eötvös, C. B., Gáspár, C., Fürjes-Mikó, Á., & Csóka, G. (2020). Known and predicted impacts of the invasive oak lace bug (Corythucha arcuata) in European oak ecosystems–a review. Folia Oecologica, 47(2), 131-139.
https://doi.org/10.2478/foecol-2020-0015
Trumbule, R. B., Denno, R. F., & Raupp, M. J. (1995). Management considerations for the azalea lace bug in landscape habitats. Arboriculture & Urban Forestry (AUF), 21(2), 63-68.
https://doi.org/10.48044/jauf.1995.011
Wheeler Jr, A.G., (1981). Hawthorn lace bug (Hemiptera: Tingidae), first record of injury to roses, with a review of host plants. The Great Lakes Entomologist, 14(1), p.5.
https://doi.org/10.22543/0090-0222.1370
Wheeler, A. G. (2008). Leptodictya plana Heidemann (Hemiptera: Tingidae): first specific host-plant and new distribution records for a seldom-collected, grass-feeding lace bug. Proceedings of the Entomological Society of Washington, 110(3), 804-809.
https://doi.org/10.4289/07-090.1
