Lace Bugs (order Hemiptera; family Tingidae) are small plant-sucking insects so named because of the lace-like pattern of the veins and membranes in their wings which are held flat over their body. 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.
The bugs have been developing throughout the season. However, this is the time of the year when their characteristic damage becomes most evident on deciduous woody ornamentals, herbaceous perennials, and some ornamental grasses.
A close examination of the leaves of plants infested with lace bugs will reveal numerous tiny yellow spots; a symptom commonly called “stippling.” The symptom is named for the art technique of repeatedly tapping the tip of a black pen on paper to produce drawings out of the numerous small dots. Speaking from personal experience, it works best if you drink a lot of coffee.
The stippling is produced by immature lace bugs (nymphs) and adults using their piercing-sucking mouthparts to stab into the succulent leaf mesophyll, sandwiched between the upper and lower epidermal layers, to rupture the cells and suck up the contents. The feeding damage produces the characteristic stippling associated with lace bugs.
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.
Eventually, the stippling will 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.
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.
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 Lace Bug Lineup
Heavy Oak Lace Bug (Corythucha arcuata) damage is occurring on oaks (Quercus spp.) in southwest Ohio with leaves becoming yellowish-white. This lace bug is native to North America but was discovered in Italy in 2000. It has since spread throughout several European countries.
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 adult. However, I could find no references showing 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 fag-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 are beginning to produce noticeable damage in Ohio include basswood lace bug (Gargaphia tiliae); buckeye lace bug (C. aesculi); chrysanthemum lace bugs (C. marmorata); hawthorn lace bug (C. cydoniae); sycamore lace bug (C. incurvata); walnut lace bug (C. juglandis); and grass lace bugs (Leptodictya plana) which is the oddball in this list.
The buckeye, 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 August in the Greater Cincinnati region.
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 as well as a few plants outside of the rose family such as common buttonbush (Cephalanthus occidentalis, family Rubiaceae).
I was surprised last year to find hawthorn lace bugs on black chokeberry (Aronia melanocarpa). However, they are most commonly found on hawthorn (Crataegus spp.), serviceberry (Amelanchier spp.), Cotoneaster spp., firethorn, (Pyracantha coccinea), and occasionally rose (Rosa spp.).
Beth Scheckelhoff (OSU Extension, Putnam County) reported during our weekly BYGL Zoom Inservice that Chrysanthemum lace bugs are running rampant in her region of Ohio. These lace bugs are unusual in that they may be found on both the lower and upper leaf surfaces.
As Beth’s images demonstrate, chrysanthemum 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 last year:
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).
Lace bug suppression includes simply applying a heavy jet of water to blast away the lace bugs. Of course, adults have wings, so they may thwart the "lace bug water park ride of doom" by simply flying back to the leaves.
Insecticidal soaps and horticultural oils are effective and have a higher safety margin for non-target insects such as beneficials (e.g., pollinators, predators, parasitoids, etc.). However, direct contact is required. So, make sure to target the undersides of leaves.
Traditional topically applied insecticides present several challenges. First, most of the insecticides that are sprayed onto plant surfaces work best as stomach poisons which present a mode of entry issue with plant-sucking insects. Lace bugs are sucking insects meaning they won’t ingest the insecticide. So, insecticide efficacy is almost entirely based on direct contact just like soaps and oils.
Second, topically applied insecticides are indiscriminate insect killers. They may kill non-target insects such as predators and parasitoids that help to regulate pest populations.
Systemic insecticides solve the mode of entry issue with plant-sucking insects and also present a lower risk to non-target insects as long as they are applied as soil drenches/injections or bark sprays (e.g., dinotefuran) rather than foliar sprays. Systemic insecticides effective against lace bugs include flupyradifurone (e.g., Altus), and acephate (e.g., Orthene, Lepitect), as well as neonicotinoids such as dinotefuran (e.g., Safari, Transtect) and acetamiprid (e.g., TriStar).
Of course, as with using any insecticide, you must read and follow label directions paying close attention to applicator and environmental safety recommendations as well as application mix ratios and timing. For example, imidacloprid must be applied with enough lead time to allow the active ingredient to migrate to the leaves in a high enough concentration to kill the bugs. It’s most likely too late for this active ingredient to have a meaningful impact on reducing lace bug symptoms this season.
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.
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.
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.
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), pp.804-809.
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.