- Control of Lace Bugs on Ornamental Plants
- Biology and Habits
- Identifying And Treating Azalea Lace Bugs
- How to Manage Pests
- Pests in Gardens and Landscapes
- How Do You Know If Lace Bugs Are Causing The Problem?
- What Do Lace Bugs Do?
- Will Lace Bug Damage Kill My Plants?
- The Best Defense Is A Good Offense!
- Getting Rid Of Lace Bugs
- Keep A Strong Cadre Of Friendly Fauna
- What About Systemic Insecticides?
- Don’t Use Broad Spectrum Insecticides
- Consistent Application Of Natural Deterrents Makes For A Win-Win!
- Managing lace bugs
- Azalea Insect Problems – Lace Bug Damage To Azaleas
- Identifying Azalea Lace Bug Damage
- How to Get Rid of Azalea Lace Bug
- Azalea pests and diseases
- Azalea lace bug
Control of Lace Bugs on Ornamental Plants
Bulletin 1102 View PDF picture_as_pdf
S. Kristine Braman
Fig. 2. Andromeda lace bug, Stephanitis takeayi, nymphs and adults. Photo: Shaku Nair, University of Georgia Fig. 1. Azalea lace bug, Stephanitis pyrioides, adults. Photo: Shaku Nair, University of Georgia Fig. 4. Grass lace bug, Leptodictya plana, adult. Photo: Kris Braman, University of Georgia Fig. 3. Hawthorn lace bug, Corythucha cydoniae, adult. Photo: Jim Baker, North Carolina State University; bugwood.org
Lace bugs are important pests of many ornamental trees and shrubs. They attack a broad range of evergreen and deciduous trees and shrubs and often go undetected until the infested plants show severe damage.
Both adults and nymphs have piercing-sucking mouthparts and remove sap as they feed from the underside of the leaf. Lace bug damage to the foliage of trees and shrubs detracts greatly from the plants? beauty, reduces the plants? ability to produce food, decreases plant vigor and causes the plant to be more susceptible to damage by other insects, diseases or unfavorable weather conditions. Repeated, heavy infestations of lace bugs may be the primary cause of plant death.
The most significant species of lace bugs that attack ornamental trees, shrubs and grasses are in the genera Stephanitis (azalea lace bug – Fig. 1 and andromeda lace bug – Fig. 2), Corythucha (hawthorn lace bug – Fig. 3 and sycamore lace bug) and Leptodictya (grass lace bug – Fig. 4)
Adult lace bugs of Stephanitis and Corythucha spp. are flattened and rectangular in shape and 1/8 to 1/4 inch long. The area behind the head and the wing covers form a broadened, lace-like covering over the body of the insect. The wings of most lace bugs are light amber to transparent in color. Leptodictya lace bugs are more elongate and oblong and greenish-grey to light brown in color.
Fig. 5. Azalea lace bug damage on azaleas. Photo: Shaku Nair, University of Georgia Fig. 6. Grass lace bug damage on ornamental grasses. Photo: Kris Braman, University of Georgia Fig. 7. Frass spots and cast skins help identify lace bug damage. Photo: Shaku Nair, University of Georgia
Lace bug nymphs are flat and oval in shape with spines projecting from their bodies in all directions. A lace bug nymph goes through five growth stages (instars) before becoming an adult. At each stage the nymph sheds its skin (molts) and these old skins often remain attached to the lower surface of infested leaves.
Azalea lace bug eggs are football-shaped and are transparent to cream colored. Hawthorn lace bug eggs, like many Corythucha species, are barrel-shaped and dark brown in color. Leptodictya eggs are similar to those of azalea lace bug. Lace bug eggs are found on the lower leaf surface, usually alongside or inserted into a leaf vein. Adult females secrete a varnish-like substance over the eggs that hardens into a scab-like protective covering.
Biology and Habits
The biology and habits of lace bugs vary somewhat according to species. Species that occur on evergreens, such as the azalea lace bug, Stephanitis pyrioides, overwinter as eggs on the underside of infested leaves. Eggs hatch in late March and early April in Georgia. The insect then passes through five nymphal instars before becoming an adult. It takes approximately one month for the insect to complete development from egg to adult and there are at least four generations per year.
Lace bugs in the genus Corythucha (hawthorn lace bug) and Leptodictya (grass lace bug) differ from Stephanitis species in that they spend the winter as adults on or near their hosts in bark crevices, mulch, tufts of grass or similarly protected areas. Spring-generation eggs are laid in small groups on the lower surface of leaves. Development from egg to adult may require four to seven weeks depending on species and climatic conditions. Three to four generations can occur in Georgia during the growing season.
Lace bug damage is readily distinguished from that of other insects and mites. Although lace bugs feed on the underside of leaves, the damage is most apparent on the upper leaf surface (Figs. 5, 6). Close examination of damaged leaves shows large numbers of adjoining chlorotic leaf cells. Positive identification of lace bug damage can then be confirmed by the presence of brown to black droplets of excrement and old “skins” of the nymphs on the underside of damaged leaves (Fig. 7).
Lace bug damage on evergreens is most common and severe on azalea, pyracantha, rhododendron and andromeda. It is especially important to prevent damage on evergreens early in the season because foliage will retain unsightly lace bug injury and be less functional for more than a year.
Lace bugs also attack a wide range of deciduous trees and shrubs. Plants found in the Georgia landscape that are commonly infested include hawthorn, cotoneaster, quince, American elm, apple, sycamore, oak and cherry. Recently, significant lace bug damage was observed on ornamental grasses, which are common in southern U.S. landscapes.
Valuable plants that are susceptible to lace bug damage should be inspected in the early spring for the presence of overwintering lace bug adults, eggs and newly hatched nymphs. Inspect these plants every two weeks during the growing season for developing lace bug infestations. Where plants have a history of lace bug infestation, control measures should be applied during the development of the first generation of lace bugs before they have caused unsightly damage.
Fig. 8. Azalea lace bug egg parasitized by mymarid wasp. Photo: Kris Braman, University of Georgia
Prior to initiating a chemical control program, look for lace bug predators and evidence of parasitized lace bug eggs on infested plants. When predators and parasites are present in the landscape, they can often help keep lace bug populations at acceptable levels. Predators of lace bugs include several mirid plant bugs. Mirid plant bugs are about the same size as adult lace bugs, but are more narrow and are bright red and black. A tiny mymarid wasp is known to parasitize eggs of both the azalea and andromeda lace bugs. When this wasp completes its development, it exits through a round hole it chews in the end of the lace bug egg (Fig. 8). Look through a magnifying glass for evidence of parasite exit holes in lace bug eggs to confirm the presence of mymarid wasps in the landscape.
If only a few lace bugs and little or no damage is observed, wash lace bugs off infested plants with a strong stream of water from a garden hose.
Repeated applications of insecticidal soaps (M-Pede®) or horticultural oils are also effective in controlling lace bug populations. In dealing with heavy infestations, chemical control is often necessary. Treatment of infested plants in early spring during the development of the first generation of lace bugs may reduce the number of insecticide applications needed to control heavy populations. Choose insecticides labeled for use against lace bugs by referring to the current edition of the Georgia Pest Management Handbook. Follow all directions, particularly safety precautions on the insecticide label. Not all of these insecticides are labeled for use on all host plants. Choose a product that is labeled for lace bug control and for application to the host plant.
Trade and brand names are used only for information. The University of Georgia Cooperative Extension, The University of Georgia College of Agricultural & Environmental Sciences does not guarantee or warrant the standard of any product mentioned; neither does the use of a trade or brand name imply approval of any product to the exclusion of others which also may be suitable.
Status and Revision History
Published on Jan 01, 2002
Unpublished/Removed on Mar 12, 2009
Published with Minor Revisions on Feb 13, 2012
Published with Full Review on Feb 17, 2015
Introduction – Distribution – Description – Life History – Hosts Plant – Damage – Management – Selected References
Azalea lace bug, Stephanitis pyrioides (Scott), belongs to a group of insects in the family Tingidae. The insects in this family generally live and feed on the underside of leaves. They have thin lacy outgrowths on their thorax, and have delicate lace-like forewings (Drake and Ruhoff 1965). At least 17 species of lace bugs cause damage to ornamental trees and shrubs in the United States.
Figure 1. Adult azalea lace bug, Stephanitis pyrioides (Scott), and excrement. Photograph by James. L. Castner, University of Florida.
Four species in the genus Stephanitis cause economic damage to plants in the heath family (Ericaceae) to which azaleas and rhododendrons belong (Mead 1967). Of the four, the most damaging species associated with landscape plants is the azalea lace bug, Stephanitis pyrioides (Cranshaw 2004).
Infested azaleas develop stippled, bleached, silvery or chlorotic symptoms similar to those caused by mites. Azalea lace bug is a pest of major concern in the nursery industry due to this aesthetic plant damage. Even in established landscape planting, azalea lace bugs can cause considerable damage to foliage if not controlled early in the season when populations are low.
Distribution (Back to Top)
Native to Japan, the azalea lace bug spread around the world through the movement of its host species, azaleas (Mead 1967). It occurs in most of the eastern United States including Florida. Available records show that it occurs in the states of Maryland, New York, Massachusetts, Virginia, Georgia, Alabama, Texas and California (CABI 2005).
Description (Back to Top)
Adult: The adult lace bug is 3 x 1.5 mm (~ 1/10 inch) long and cream-colored. The netted lacy wings, marked with black or brown patches, are held flat over the body with outer margins extending beyond the body outline. Unless observed closely, the small size and transparent wings make it less apparent. When observed under a hand lens, a characteristic hood can be seen over the head.
Figure 2. Adult azalea lace bug, Stephanitis pyrioides (Scott). Photograph by Jamba Gyeltshen, University of Florida.
Egg: The white oval or flask shaped egg is 0.36 to 0.43 mm (~ 0.02 inch) long and 0.16 to 0.23 mm (0.02 inch) wide with a bent ‘neck’ to one side (Shen et al. 1985). Eggs are usually laid along the midrib or leaf margins of young leaves and covered with a dark brownish adhesive material that hardens to form a protective coating (Drake and Ruhoff 1965, Shen et al. 1985).
Nymph: The nymph is colorless upon hatching but soon turns black and spiny. It goes through five instars, ranging in size from 0.1 mm (0.004 inch) to 1.8 mm (0.07 inch). Wing pads can be seen after the fourth molt.
Figure 3. Nymphs of the azalea lace bug, Stephanitis pyrioides (Scott), with several cast skins and excrement. Photograph by James. L. Castner, University of Florida.
Figure 4. Nymphs of the azalea lace bug, Stephanitis pyrioides (Scott). Photograph by Jamba Gyeltshen, University of Florida.
Life History (Back to Top)
Females lay groups of partially embedded eggs on the underside of leaves, generally along the midrib but also on lateral veins and occasionally on the upper leaf surface (Neal and Douglass 1988). Over 300 eggs, at the rate of five to seven eggs per day are laid during the adult stage. The development period of eggs vary from about 12 days at 31.7°C to 22 days at 20.6°C.
Nymphs emerge from the eggs and feed in small clusters, often near the empty eggshells. Their development through five instars also depends on temperature, taking 10.5 days at 31.7°C to about 23 days at 20.6°C. From egg to adult, it would take 22 to 45 days within a temperature range of 20.6 to 31.7°C. The longevity of adult varies from one to four months under the same range of temperature. Between two to four generations are completed in a year. This species overwinters in the egg stage.
Hosts Plant (Back to Top)
Recognition of the host plant is helpful in identifying lace bugs because they are generally fairly host-specific (Drake and Ruhoff 1965). The azalea lace bug is particularly injurious to evergreen azalea (Rhododendron spp.) varieties, although deciduous varieties may also be attacked.
Damage (Back to Top)
Nymphs and adults cause damage by piercing and removing cell contents from leaf tissues. Adult females cause more feeding injury than adult males and nymphs (Buntin et al. 1996). Lace bugs insert their stylet through stomata on the lower leaf surface and feed almost entirely on upper palisade parenchyma (Ishihara and Kawai 1981, Buntin et al. 1996). Because of the removal of most of the chlorophyll containing tissues located near the upper epidermis, the leaf surface become stippled, bleached, silvery or chlorotic.
Figure 5. Damage caused by azalea lace bug, Stephanitis pyrioides (Scott), feeding. Photograph by James. L. Castner, University of Florida.
Figure 6. Damage caused by azalea lace bug, Stephanitis pyrioides (Scott), feeding. Photograph by James. L. Castner, University of Florida. Severely damaged leaves become heavily discolored and eventually dry or fall off. Symptoms may sometimes be confused with mite injury, but the presence of brown varnish-like excrement, frequently with cast skins attached, suggest lace bug damage (Johnson and Lyon 1991).
Figure 7. Severe damage caused by azalea lace bug, Stephanitis pyrioides (Scott), feeding. Photograph by James. L. Castner, University of Florida.
Figure 8. Severe damage caused by azalea lace bug, Stephanitis pyrioides (Scott), feeding. Photograph by Jamba Gyeltshen, University of Florida.
Figure 9. Azalea leaf with azalea lace bugs, Stephanitis pyrioides (Scott), and excrement spots. Photograph by James. L. Castner, University of Florida.
Generally, lace bug damage appears to be greater in sunny areas possibly because of a high rate of natural predation in the shade (Trumble and Denno 1995).
Management (Back to Top)
Pest management decisions in ornamental plants are mainly influenced by aesthetic considerations as there will often be no acceptable level of apparent damage for sale of a nursery crop (Klingeman et al. 2001). Since early season damage on broadleaf evergreens may result in aesthetic injury for the remainder of the growing season, it is important to control lace bugs early.
Monitoring. Plants should be monitored weekly in the spring, summer and fall for the presence of lace bugs. As initial damage symptoms may not be apparent, it is important to sample the leaves and observe the undersides with a powerful hand lens. Lace bugs can be also be detected by beating the shrub (to dislodge) and collecting them on a white sheet of paper.
Cultural control: Maintaining healthy plants with proper watering and fertilizer treatments reduces plant stress as well as damage potential. Growing azaleas in shadier areas also reduces damage.
Mechanical control. A hard jet of water from a garden hose could be directed on the undersides of the foliage to dislodge the bugs and possibly kill the nymphs, but any remaining live lace bugs may still damage the foliage.
Chemical control. Spring is the best time to control the first or second generation of lace bugs. Insecticidal soap, horticultural oil, neem oil and most synthetic insecticides provide good control. It is important to direct the spray to undersides of the leaves for optimal coverage. Some systemic insecticides could also provide season-long control if poured around the roots of azaleas in spring.
For chemical control under Florida conditions, see:
Insect Management Guide for landscape plants
- Buntin GD, Braman SK, Gilbertz DA, Phillips DV. 1996. Chlorosis, photosynthesis, and transpiration of azalea leaves after azalea lace bug (Heteroptera: Tingidae) feeding injury. Journal of Economic Entomology 89:990-995.
- CABI. (2005). Azalea lace bug, Stephanitis pyrioides (Hemiptera: Tingidae). Crop Protection Compendium. CAB International 2005.
- Cranshaw W. 2004. The Ultimate Guide to Backyard Bugs: Garden Insects of North America. Princeton University Press, Princeton and Oxford. 384 pp.
- Drake CJ, Ruhoff FA. 1965. Lace bugs of the World – A Catalog (Hemiptera: Tingidae). Smithsonian Institution, Washington D.C. United States National Museum Bulletin 213. 634 pp.
- Ishihara R, Kawai S. 1981. Feeding habits of azalea lace bug, Stephanitis pyrioides Scott (Hemiptera: Tingidae). Japanese Journal of Applied Entomology and Zoology 25:200-202.
- Johnson WT, Lyon HH. 1991. Insects that Feed on Trees and Shrubs. Comstock Publishing Associates, Cornell University Press, Ithaca and London.
- Klingeman WE, Buntin GD, Braman SK. 2001. Using esthetic assessments of azalea lace bug (Heteroptera: Tingidae) feeding injury to provide thresholds for pest management decisions. Journal of Economic Entomology 94:1187-1192.
- Mead FW. 1967. Stephanitis Lace Bugs of the United States (Hemiptera: Tingidae). Florida Department of Agriculture and Consumer Services, Division of PlantIndustry, Entomology Circular No. 62.
- Neal JW Jr., Douglass LW. 1988. Development, oviposition rate, longevity, and voltinism of Stephanitis pyrioides (Scott) (Heteroptera: Tingidae). Journal of Economic Entomology 93: 352-356.
- Shen HW, Wu WJ, Yang PS. 1985. The biology of the lacebug, Stephanitis pyrioides (Scott). Yen chiu pao kao (Memoirs of the College of Agriculture, National Taiwan University vol. 25, no 1, pp. 143-154).
- Trumble RB, Denno RF. 1995. Light intensity, host-plant irrigation, and habitat-related mortality as determinants of the abundance of azalea lace bug (Heteroptera: Tingidae). Environmental Entomology 24: 898-908.
Identifying And Treating Azalea Lace Bugs
The azalea lace bug can cause significant damage to the leaves of azalea bushes. Noticing them is an important step so treatment can be administered quickly. If this pest isn’t taken care of early in the season, extensive damage to foliage can occur. By learning the characteristics of an azalea lace bug infestation, and knowing proper treatments, you can cure your azalea and prevent future lace bug outbreaks. These bugs actually pierce cells and remove the contents, which will display the signs of infestation.
The first signs of the azalea leaf bug infestation are similar to those of other unwanted pests. Symptoms start on the underneath of the leaves, but unless you check them regularly, you won’t notice until they’ve progressed to the upper part of the foliage.
First signs are small bleached spots that start off as a color significantly lighter than the leaf, then go to a yellow shade. With extensive damage, leaves may turn completely brown and die, falling from the limbs. Once the leaf is lifted and you look underneath, infestation will be obvious. Unless you spot one of the actual bugs, you’ll likely see egg pouches underneath the newer leaves, and spots along where the middle vein meets with the other periphery veins. A dark adhesive is used to bond the eggs to the leaf, so you will see the pouches as a brown-white.
Once nymphs have hatched, they quickly turn black and look very spiky if observed closely enough. Sometimes you will see the actual adults. These are called lace bugs because their wing patterns make it look as though they’re made of lace. Adults are a cream color and grow to be about an eighth of an inch long, with wings that are partially transparent and extend the length of their bodies. Sometimes you will catch one of them under leaves when you take a look.
Treatment of Azalea Lace Bugs
To avoid treatment, taking proper care of your azalea can make all the difference. Many infestations can be avoided by keeping your plant strong and healthy. Keep your azalea watered and properly fertilized. Regularly take leaf samples and look at the top and underside of leaves with a magnifying glass.
If you find that you still have lace bugs, a light infestation can be cured by spraying hard jets of water on the underside of the leaves. This will dislodge nymphs, eggs and brush off adults. If you have a more advanced problem with lace bugs, there are some chemical control options.
If more than 20% of leaves are damaged, chemical use is advised. Systemic insecticides are suggested for their fast-acting properties. Sevin is a widely known insecticide for treatment of lace bugs, as is Bayer Advanced and Spectricide for rose and flower insects. A few insecticides for commercial use include Sevin SL, Organicide and Astro. Many of these have formulas meant to spray directly onto foliage or work into soil.
How to Manage Pests
Pests in Gardens and Landscapes
In this Guideline:
Lace bug adults, nymph and black feces.
Christmas berry tingid nymph.
Excrement-covered lace bug eggs laid partly in leaf.
Bleached, stippled foliage caused by lace bug feeding.
Green lacewing larva eating a lace bug nymph.
Over a dozen species of lace bugs (family Tingidae) occur in California. Each feed on one or a few closely related plant species. Hosts include alder, ash, avocado, coyote brush, birch, ceanothus, photinia, poplar, sycamore, toyon, and willow.
Adult lace bugs are about 1/8 inch (3 mm) long with an elaborately sculptured dorsal (upper) surface. The expanded surfaces of their thorax and forewings have numerous, semitransparent cells that give the body a lacelike appearance, hence the name “lace bugs.” The wingless nymphs are smaller, oval, and usually dark colored with spines. Adults and nymphs occur together in groups on the underside of leaves.
Native species named after their host plants include the California Christmas berry tingid (Corythucha incurvata), ceanothus tingid (Corythucha obliqua), and western sycamore lace bug (Corythucha confraterna). The introduced avocado lace bug (Pseudacysta perseae) is a pest of avocado (Persea americana) and camphor tree (Cinnamomum camphora).
Lace bugs develop through three life stages: egg, nymph, and adult and have several generations a year. Females insert tiny, oblong eggs in leaf tissue and cover them with dark excrement. Nymphs (immatures) develop through about five, increasingly larger, instars (growth stages) over a period of weeks before maturing into adults. Lace bugs can overwinter as eggs in leaves on evergreen hosts and as adults in protected locations, such as under bark plates and fallen leaves and other debris beneath host plants. All life stages can be present throughout the year on evergreen hosts in areas with mild winters.
Lace bug adults and nymphs feed on the underside of leaves by sucking fluids from plants’ photosynthetic tissues. This causes pale stippling and bleaching that can become very obvious on the upper leaf surface by mid to late summer. Adults and nymphs also foul leaves with specks of dark, varnishlike excrement; and this excrement sometimes drips onto pavement and other surfaces beneath infested plants. Certain other true bugs and thrips also produce leaf stippling and dark excrement. Mites also stipple leaves. Mite infestations usually can be distinguished by the absence of dark excrement and sometimes by the presence of mite cast skins and fine silken webbing. Examine the lower leaf surface, using a magnifying lens if necessary, to identify what type of pest is causing the damage.
Lace bug feeding is not a serious threat to plant health or survival. Prolonged high populations of lace bugs may cause premature drop of some leaves and a modest reduction in plant growth rate. On avocado premature leaf drop may lead to sunburn of some fruit and a subsequent reduction in fruit yield.
Tolerate lace bug damage where possible. The injury is mostly aesthetic (cosmetic) and does not seriously harm plants. Provide proper cultural care so plants are vigorous. Conserve predators and parasites and apply cultural controls as discussed below to help suppress populations of at least some species of lace bugs.
No treatment will restore stippled foliage, which remains until pruned off or replaced by new growth. If intolerable damage has occurred, during subsequent years inspect plants about once a week beginning in late winter. Take action when lace bug nymphs become abundant and before damage becomes extensive. A forceful stream of water directed at the underside of leaves beginning early in the season, when nymphs are the predominant life stage, and repeated at intervals can help to suppress, where feasible, lace bug populations on small shrubs. Various insecticides are available for use on landscape plants, but these products can adversely affect beneficial invertebrates and the environment.
Grow plants that are well adapted to conditions at the site. Consider replacing plants that perform poorly or repeatedly experience unacceptable pest damage. Certain plant species growing in hot, sunny locations are more likely to be damaged by lace bugs. For example, azalea and toyon grown under partial shade experience less damage by lace bugs than when they are grown in locations more exposed to direct sunlight and higher temperatures. Provide adequate irrigation and otherwise provide plants with appropriate care.
On toyon and possibly other shrubs, lace bug survival during winter and subsequent damage in spring may be reduced by keeping soil beneath host plants bare during December through February, by shallowly cultivating the soil surface several times during this period, or using both practices. For example, during late fall rake away and compost leaves beneath lace bug host plants. If organic mulch is reapplied in spring, avoid using leaves from the same plant genus as mulch near that plant because it may harbor adult lace bugs.
Natural enemies of lace bugs include parasitic wasps, predatory assassin bugs, lacewing larvae, lady beetles, jumping spiders, pirate bugs, and mites. These beneficial species may not appear in sufficient numbers until after lace bugs become abundant, but their preservation is an essential part of a long-term, integrated pest management program. To increase natural enemy abundance and reduce lace bug damage, grow a variety of flowering plant species and provide partial shade to shrub species that are not adapted to grow in full sun. If applying pesticides, choose nonpersistent, contact insecticides to minimize the adverse effects on beneficial predators and parasites.
Insecticides will not restore an undamaged appearance, but can reduce or prevent further damage. Apply insecticide only when pests are present or expected to become too abundant. Insecticides can have unintended effects, such as contaminating water, poisoning natural enemies and pollinators, and causing secondary pest outbreaks. Completely read and follow the product label instructions for the safe and effective use of that insecticide.
Nonresidual, Contact Insecticides
When properly applied, almost any contact insecticide will control lace bugs. Contact insecticides that do not leave persistent, toxic residues include azadirachtin (Safer BioNeem), insecticidal soap (Safer), narrow-range oil (Monterey Horticultural Oil, Volck), neem oil (Green Light, Garden Safe), and pyrethrin products, which are often combined with the synergist piperonyl butoxide (Ace Flower & Vegetable Insect Spray, Garden Tech Worry Free Brand Concentrate).
These insecticides have low toxicity to people and pets and relatively little adverse impact on the populations of pollinators and natural enemies and the benefits they provide. To obtain adequate control, thoroughly wet the underside of infested leaves with spray beginning in spring when lace bug nymphs become abundant. To provide adequate control, application may need to be repeated.
Systemic insecticides are absorbed by one plant part (e.g., trunks or roots) and moved (translocated) to leaves or other plant parts. In comparison with systemics that are sprayed onto foliage, products labeled for soil drench or injection or for trunk injection or spraying minimize environmental contamination and may be more effective. Trunk application of systemic insecticides can provide relatively rapid control. There is a longer time delay between soil application and insecticide action. Some uses require hiring a professional pesticide applicator. Certain home-use products can easily be drenched into soil around the tree trunk using the mix-and-pour method.
Systemic insecticides available for use against lace bugs include the neonicotinoids dinotefuran (Safari) and imidacloprid (Bayer Advanced Tree & Shrub Insect Control, Merit) and the organophosphate acephate (Lilly Miller Ready-to-Use Systemic, Orthene). When properly applied, one application may provide season long control.
Some systemic insecticides can cause spider mite outbreaks and are toxic to beneficial insects that are directly sprayed or come into contact with treated leaves. Systemics can translocate into flowers and have adverse effects on natural enemies and pollinators that feed on nectar and pollen. Do not apply systemic insecticides to plants during flowering or shortly before flowering; wait until after plants have completed their seasonal flowering unless the product’s label directions say otherwise. With soil application, when possible, wait until nearby plants also have completed flowering, as their roots may take up some of the soil-applied insecticide.
If applying systemic insecticide, use soil application or a trunk spray whenever possible. With trunk injection and implantation, it is difficult to repeatedly place insecticide at the proper depth. These methods also injure woody plants and can spread plant pathogens on contaminated tools. When injecting or implanting into multiple plants, scrub any plant sap from tools or equipment that penetrate bark and disinfect tools with a registered disinfectant (e.g., bleach) before moving to work on each new plant. At least 1 to 2 minutes of disinfectant contact time between contaminated uses is generally required. Consider rotating work among several tools, using a freshly disinfected tool while the most recently used tools are being soaked in disinfectant. Avoid methods that cause large wounds, such as implants placed in holes drilled in trunks. Do not implant or inject into roots or trunks more than once a year.
Residual, Foliar Sprays
Foliar sprays of broad-spectrum insecticides with residues that can persist for weeks are not recommended for lace bug control. Pesticides to avoid include carbamates (carbaryl or Sevin), nonsystemic organophosphates (malathion), and pyrethroids (bifenthrin, fluvalinate, permethrin). These are highly toxic to natural enemies and pollinators and can cause outbreaks of spider mites or other pests. Because their use in landscapes and gardens can run or wash off into storm drains and contaminate municipal wastewater, these insecticides are being found in surface water and are adversely affecting nontarget, aquatic organisms.
WARNING ON THE USE OF PESTICIDES
Pemberton, C. 1911. The California Christmas-berry Tingis. J. Econ. Entomol. 4(3):339–346.
Pest Notes: Lace Bugs
Produced by University of California Statewide IPM Program
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Other specific lace bugs that only eat a certain plant include:
- Azalea plant (Azaleas Lace Bugs)
…to name a few. The list goes on and on to include a wide variety of plants, shrubs and bushes. The various species are typically named after the type of plant they consume. Luckily, dealing with lace bugs successfully uses similar methods for their control
How Do You Know If Lace Bugs Are Causing The Problem?
Lace bugs go through three life stages. They go from eggs to nymphs to adults, and all on the bottom sides of plant leaves.
Adult females lay very tiny, oblong eggs in the tissue of a leaf surface. The eggs hatch into nymphs which shed their skins about five times before becoming adults and starting the cycle all over again.
It’s easy to identify these little devils. Even as adults, they are extremely tiny. In fact they never exceed 1/8th inch in length. Winged adults look “lacy” with tiny, clear cells covering the thorax and wings.
The wingless lace bug nymphs, dark in color and oval in shape are even smaller than adults. You can find both nymphs and adults clustered together on the undersides of the leaf on your shrubs, bushes and other plants.
When you look at the lower sides of your plant leaves and see dark, shiny spots, tiny black bugs and tiny, fly-like insects with lacy wings, you know you are dealing with lace bugs.
Recognizing Lace Bugs Video:
What Do Lace Bugs Do?
Both the nymphs and the adults suck the fluid from plants (like the scale insect pest and spider mites) through the undersides of the leaves. This interferes with photosynthesis and causes stippling and discoloration of the leaf. You will usually see this severe damage in the later weeks of summer.
Before the damage occurs, you may notice the spots of dark, shiny excrement on the undersides of your plants’ leaves. In very heavy infestations, this can actually drip onto the ground beneath the plants.
When you see these symptoms, you can be fairly certain that you are dealing with lace bugs; however, some other types of pests also cause this kind of damage. Among them are mites, thrips and true bugs.
If you are uncertain, use a magnifying glass to examine the damage and look for clues. If spider mites cause the infestation, the dark, shiny droppings will not be present. Additionally, mites cast webs and they also shed their skin with great frequency. You will see tiny mite skins cast about with a spider mite infestation.
Will Lace Bug Damage Kill My Plants?
Here’s how to get rid of lace bugs.
Lace bug damage is unsightly, but not fatal. Your plants, shrubs and trees will have an unattractive appearance due to the discoloration of the leaf and the dark, ugly spotting, but will not die.
If your plants suffer heavy infestation for a long time, they may drop their leaves. This can cause a reduction in fruit production for some types of trees. Also, a dearth of leaves can allow the sun to damage fruit.
The Best Defense Is A Good Offense!
You cannot undo the damage caused by lace bugs, but there are lots of ways to get rid of the bugs so the new growth can come in undisturbed next spring. Keeping plants strong and healthy will help repel the pests and prevent infestation.
#1 – Attract Natural Predators!
You don’t really need to completely eradicate lace bugs to keep damage under control. Cultivating a good population of desirable fauna in your garden will help. Lace bugs have a number of natural enemies, including:
- Lady Bugs learn more about Lady Bugs here
- Pirate bugs
- Predaceous mites
- Lacewing larvae more on Green Lacewings here
- Jumping spiders
- Parasitic wasps
- The Assassin bug of which there are 100’s
Here’s more detailed look at how these insects help gardeners combat lace bug infestation.
Lady bug species actually feed on lace bugs as well as other insects that destroy plants.
Pirate Bugs, another natural enemy of lace bugs measuring about 1/5 inch in length, love feeding on other insects and the eggs of their prey and are probably the most beneficial insects for controlling lace bug infestation.
They use their beak or proboscis for piercing the bodies of their victims and sucking out their fluids causing death.
Although very beneficial for controlling lace bug infestation, be careful when using them since ornamental plants, shrubs, corn, small grains, and growing tomato plants attract them.
They can feed on the juices and pollen of the plants that they favor in your garden. Luckily, this only happens when prey is unavailable.
On another note, pirate bugs can bite humans during late summer and the bites are said to be rather painful. The presence of pirate bugs is seasonal and many homeowners prefer using them in the springtime when the lace bugs cause the greatest damage.
Predatory Mites love consuming harmful plant-eating insects such as lace bugs. However, unlike pirate bugs, they don’t damage plants or bite humans. Related to ticks and spiders they look nearly identical to spider mites.
Predatory mites use tiny mouth parts that extend from the top of their pear-shaped bodies to attack, pierce, and kill their prey. Typically, predatory mites will disperse once they finish consuming all the available prey.
Lacewing Larvae can ruthlessly destroy many of the bugs in your garden by injecting venom and sucking fluid from their victims.
A handful of lacewing larvae like these can aid in the control of lace bug infestation and protect the garden from various other insects including controlling aphids.
Lacewing larvae can consume up to 200 plant-eating bugs every week, making them highly beneficial insects.
Assassin Bugs typically brown, reddish, or black bugs and when mature usually measure about 0.75 inch. These predators feed on insects but some assassin bug species actually feed on the blood of mammals.
While adult assassin bugs may not be the best of fliers, they can sufficiently stalk lace bug prey. Once assassin bugs get into contact with lace bugs or other insects such as caterpillars or aphids, they usually inject them with a deadly venom.
Attract these beneficial allies to your garden and you will need little or no pesticides.
#2 – Plant With Care!
Planning carefully when planting your yard and garden will also help prevent lace bug infestation. Examples of good planning include:
Don’t plant a mono-crop. Plant a wide variety of plants, shrubs and trees and mix them up so that lace bugs will not have a chance to become firmly established.
Avoid planting in very hot, dry, sunny areas as this is where lace bugs thrive. Try to choose plants that like partial shade and position them in such a way that your plants receive light shade and/or afternoon shade every day.
Be sure your plants are well watered and keep soil evenly moist by applying mulch.
Prevent lace bugs taking hold in the springtime by examining your plants late in the winter. If you notice any lace bug presence, take action to eradicate them before they can begin reproducing.
Getting Rid Of Lace Bugs
The lace bug critters can be very hard to get rid of because they are capable of over-wintering on their host plants in a number of ways.
- Adults can hide out under bark plates.
- Eggs and adults may find shelter in debris and fallen leaves under host plants.
- Nymphs and adults infesting an evergreen plant can handily survive a mild winter.
- Eggs inserted into evergreen plant tissues can survive winter and hatch in the springtime.
There are lots of natural ways to tackle lace bugs, and it’s a good idea to practice all of them all of the time. An ounce of prevention really is worth a pound of cure when it comes to dealing with these tenacious little invaders. Here are a few smart biological control or natural ideas you can try:
#1 – Knock them off with water. Early in the spring, give the undersides of your plant leaves a good dousing with the garden hose. A forceful spray will knock off nymphs and adults and wash the unsightly droppings off your plants’ leaves.
#2 – Prune vigorously and dispose of the cut leaves properly. After washing down your plants, cut off damaged leaf or leaves and seal them up in a plastic bag to be taken away with the trash.
#3 – Rake up debris, leaves and old mulch from beneath affected plants and dispose of it properly. Replace it with a sterile commercial mulch or with mulch not made from a type of plant that attracts lace bugs.
#4 – Choose plants that will do well in your location. While it may be tempting to plant unusual and exotic types of plants, this is really asking for lace bug problems. Healthy, hardy, native and naturalized plants that thrive with ease in your conditions are far more likely to fight off lace bugs.
#5 – Cull out poor performing plants and replace them with hardier varieties.
#6 – If you have plants severely affected last spring, between the months of December and February, keep the ground beneath them bare and clean. Rake up leaves, debris and mulch and cultivate the soil several times during these late winter months. This will expose and kill any eggs, nymphs or adults lurking in the soil.
Keep A Strong Cadre Of Friendly Fauna
Take great care when using broad spectrum insecticides as these products will kill off your friendly fauna. If you kill lace bug predators, you will soon find yourself dealing with a spider mite infestation.
Keeping a healthy population of natural predators in the landscape plays an important part of long term pest control of many different, undesirable insects. If you find that natural predators cannot keep up with the lace bug infestation, use only a non-persistent, contact insecticide treatment.
Apply these types of products directly and carefully to the lasce bug infestation. Their short term actions will carry effect on your beneficial fauna.
Some of the best products to use include:
- Neem extract read our detailed review on Neem Oil Insecticide for Plants Here
- Fertilome triple action pest management which uses 70% neem oil
- Insecticidal Soap more details in using Insecticidal Soap here
- Narrow range oil or horticultural oils
Spray the undersides of leaves with one of these products once every two weeks until the problem clears up. Plants will still look ragged, but the infestation under control. Taking preventative steps through the winter months, allow plants to recover and grow back nicely in the springtime.
Use chemical treatments sparingly and as a last resort. They can cause more damage than benefit in your garden. Commercial insecticides can:
- Kill off valuable pollinators such as bees and butterflies
- Result in the increase of other pest (e.g. spider mites)
- Poison lace bugs’ natural enemies
- Contaminate water supplies
If you do resort to chemical treatment, be sure to read the label instructions carefully and follow them to the letter.
Some effective chemicals when used correctly include these non-residual contact insecticides:
- Piperonyl Butoxide
These types of insecticides carry a low toxicity to humans and domestic animals.
When applied judiciously and with great care, they will have limited negative impact on natural insect predators and pollinators.
If your lace bug battle goes on for a couple of seasons without effect, apply one of these products carefully to the undersides of leaves in early spring. Repeat the treatment bi-weekly. This will do away with adults and emerging nymphs on a regular, ongoing basis.
What About Systemic Insecticides?
Plant’s absorb systemic products and spread the “poison” throughout the plant’s circulatory system. Typically, the application of these products gets delivered through foliar spray, trunk injection or soil drench.
Depending upon the type of poison and the type of plant, you may need to hire a pest control service to help you with this.
Some of the systemic insecticides commonly used against lace bugs: include
- Organophosphate Acephate
In severe cases, a single application of one of these powerful products may eliminate the lace bug problem. Unfortunately, it may also do away with the pollinators and your beneficial fauna.
You may have heard that bees are dying off at alarming rates around the world. This is because of the use of neonicotinoids. Bees are essential to life on earth, so killing them off in mass numbers is sheer folly.
When poured into the ground (soil drench) or applied as a foliar spray, systemic insecticides can travel to plants other than the target plant. If they translocate to flowering plants and are consumed by pollinators in nectar and pollen, massive deaths will result. Furthermore, use of systemic insecticides is very likely to result in spider mite infestation.
Don’t Use Broad Spectrum Insecticides
Avoid broad-spectrum insecticides and those that leave persistent residues. Specific products to avoid include:
- Pyrethroids, such as permethrin, fluvalinate and bifenthrin
- Nonsystemic organophosphates, such as malathion
- Carbamates, such as Sevin and carbaryl
All of these are extremely poisonous and can decimate your population of natural insect predators and pollinators. Additionally, when you poison insects, you are also poisoning other wildlife that eats them, such as birds, toads, lizards, box turtles and so on.
Furthermore, these poisons don’t just stay politely in your garden poisoning your only your wildlife. Rain and watering cause them to run off into storm drains and streams where they cause damage to aquatic life and eventually contaminate drinking water.
- What other “Bad Bugs” like to visit your garden? Check out this list of 30 “Bad Bugs”
Consistent Application Of Natural Deterrents Makes For A Win-Win!
All-in-all, it’s best to simply avoid using these powerful and potentially dangerous products. When you choose hardy plants, position them in your yard carefully and tend to them well, they are unlikely to become infested with lace bugs. If you do have a lacebugs problem, a tenacious effort using natural or less hazardous methods will surely be effective.
Managing lace bugs
Plants that are drought stressed are more susceptible to insect pests and diseases. As we discussed in last week’s post about drought stress in trees, stressed plants often emit distress signals that many damaging insects pick up on.
We are seeing signs of lace bug damage on rhododendrons and azaleas in some of our clients’ landscapes. We also sometimes see damage on other broadleaf evergreens such as pieris. Damage may be especially apparent when the plants are also showing signs of stress from too little water.
Given our current hot, dry weather, we decided to update a blog post from last year about managing this pest. Unfortunately, at this time of year there is little you can do except to keep your plants well watered. But you can begin planning for a better situation next year.
Lace bug damage on rhododendron. Photo: Clemson University – USDA Cooperative Extension Slide Series, Bugwood.org
How to tell if you have lace bugs
When lace bugs feed, they cause yellow pinpoints in the leaves. Heavily damaged leaves appear yellow. Lace bugs suck the life out of leaf tissue and may eventually kill your shrubs.
Lace bugs are about 1/8 inch long. They have clear wings sporting dark blotches in a lacy pattern. Eggs appear as black or brown dots on the underside of leaves. Nymphs look like tiny clear, yellow or black spiky things. Females lay eggs partly into the plant tissue, hidden under poop.
There are several types of lace bugs, including the rhododendron lace bug and the azalea lace bug. The latter is a native of Japan. It has only been found in the Pacific Northwest since 2008.
What we can do
Contact us if you would like help controlling lace bugs. We use M-Pede oil to reduce populations. It is made from a fatty acid. It’s safe and has limited effects on beneficial insects. We start monitoring for lace bugs in our clients’ landscapes in spring because nymphs are easier to kill than adults.
Evergreen shrubs with lace bug damage now will continue to show damage until leaves drop in two years. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org.
What you can do
- Keep your plants well watered and don’t over-fertilize. Watch our video on how to water to make your plants strong and healthy. Stressed plants (e.g., from too much sun) are more likely to be damaged by lace bugs. Most rhododendrons and azaleas prefer partial shade. A healthy plant will better resist insect damage.
- Don’t rake everything out of the beds. Leave mulch to protect roots. Make sure roots are not exposed. Thick layers of mulch also help reduce drought stress.
- Apply mulch or compost to beds in fall or spring when soil is moist and cool. Mulch keeps moisture in the soil and prevents shrubs from drying out. Remember to keep a 6-8 inch space between mulch and the plant stem.
- Encourage beneficial insects by planting low-growing plants such as grasses, heather, salal, epimedium and other evergreen perennials. Several beneficial insects feed on lace bugs, including earwigs, green lacewings, lady beetles, minute pirate bugs, plant bugs, spiders and tree crickets. Research has shown that releasing lacewings among target plants reduces damage from lace bugs.
- Look for and destroy eggs and nymphs in spring. You could use a nontoxic spray such as horticultural oil, insecticidal soap and neem-based products. Coat the leaves well, including on the underside. Repeat regularly. Chemical insecticides kill important pollinators and beneficial insects that kill other pests.
- Decide how important your plant is to you and how much you want to do to manage the problem. You may choose to replace problem plants with something that takes less work to look good and stay healthy.
‘Autumn Twist’ is one of several Encore azalea cultivars that are resistant to lace bugs.
- Resistant Encore azalea cultivars include ‘Autumn Amethyst’, ‘Autumn Twist’, ‘Autumn Royalty’, ‘Autumn Sangria’, ‘Autumn Cheer’, and ‘Autumn Rouge’. Among evergreen azaleas, the cultivar ‘Micrantha’ shows some resistance. Deciduous azaleas with the most resistance are Rhododendron canescens and R. periymenoides.
- Resistant pieris varieties include Pieris phillyreifolia and P. japonica ‘Variegata.’
- If you would prefer another type of shade-tolerant flowering shrub, try native Oregon grape, red flowering currant or exotic kalmia, hydrangea, osmanthus or daphne.
Pests of Landscape Trees and Shrubs, an Integrated Pest Management Guide. 1994. UC Publication 3359.
Azalea Lace Bug: Biology and management in commercial nurseries and landscapes, Oregon State University.
Azalea lace bug, Oregon Metro. Azaleas, rhododendrons face severe threat from lace bugs, The Oregonian.Bugs & blights: lace bugs
You may have seen the damage lace bugs do to azaleas without knowing who did the dirty deed. Lace bugs suck the juice out of individual leaf cells. Since they hide underneath azalea leaves, you’ll never notice the bugs but it’s easy to see their damage. Since the bugs slurp out the chlorophyll in a leaf cell, the top of the leaf has hundreds of yellow speckles. Thousands of hungry lace bugs can make an azalea appear yellow all over.
Since azalea lace bugs have an active sex life, just a few can produce thousands of offspring in the course of a summer. Dr. Kris Braman says that she has seen adult lace bugs on her research azaleas even during the winter.
Inspect your azaleas for speckled yellow leaves. Examine the backside of the leaves too. If you see tiny black spots scattered across the leaf and concentrated along the mid-vein, you will have a population explosion of the creatures before many weeks pass.
The adult lacebug is barely one fourth inch long, with transparent wings. It feeds on the underside of azalea leaves, sucking juice from the leaf cells.
Mid-spring is a great time to control the first few generations of lacebug larvae and adults. There are two options:
1. and most will kill the insects. The key to good control, though, is thorough coverage and repeat sprayings in summer, every four weeks.
Use a garden sprayer and pump it up vigorously. When spraying, point the spray wand up from beneath so the undersides of the leaves are covered with spray.
2. Another pesticide option is to use a systemic insecticide like that poisons the sap of the azalea. They can be applied around the roots of azaleas in spring, when growth begins, to achieve season-long control. This is usually the easiest method to achieve control.
It is much easier to manage azalea lacebugs in spring or summer than it is in August!
Azalea lacebug symptoms
Tags For This Article: azalea, insects, lace bug, lacebug, systemic
Azalea Insect Problems – Lace Bug Damage To Azaleas
Azaleas are a popular landscaping plant due to their ease of care and their beauty, but for all their ease, they are not without a few problems. One of those is the azalea lace bug. These azalea insects can cause significant damage to a plant if not controlled. Lace bug damage to azaleas tends to be cosmetic, but they can ruin the look of a carefully tended azalea very quickly.
Identifying Azalea Lace Bug Damage
Lace bug damage to azaleas normally occurs on the leaves and will look like silvery, white or yellow spots. This is caused by these azalea insects, literally sucking small sections of the leaf dry and killing that section of the leaf. As these azalea leaf pests move on across the leaf, more and spots will appear.
You will also know if you have these azalea insect problems by looking at the underside of the leaves, where the azalea lace bug tends to be found. If you see a sticky black substance or a rust color, this is another sign that you have these azalea insects.
You may even find the azalea lace bug or nymph on the leaves. The adult azalea lace bug can be identified by their “lace” like wings while the nymphs will merely look like tiny spots.
The azalea lace bug prefers evergreen azaleas but can also attack the deciduous varieties as well.
How to Get Rid of Azalea Lace Bug
These azalea insect problems are best avoided in the first place. The azalea lace bug tends to attack plants that are already weakened due to poor fertilizing or watering, so make sure to take proper care of your plants.
If your azalea shrub is already infested with these azalea leaf pests, you can try one of two methods for getting rid of them. The first is chemical controls and the other is organic control.
Chemical control involves using insecticidal soaps (some of which are organic) and most off the shelf insecticides will effectively kill azalea lace bugs.
For organic control of these azalea insects, you can try several methods. The first method to try is to spray the plant down with a sprayer on the hose. This can knock the pests of the plant and disorient them enough to prevent re-infestation.
You can also try spraying the plants with neem oil or white oil.
Lace bug damage to azaleas does not have to be devastating. With a little know how, these azalea insect problems can be dealt with and eliminated. Azalea lace bugs do not have to reduce the beauty of your plants.
Azalea pests and diseases
Azalea lace bug
Identification and symptoms of attack
Azalea lace bug (Stephanitis pyrioides) is an introduced insect. Its common name comes from the raised network of veins on its clear, hardened forewings.
Adults are 4–6mm long, and mottled black and tan. Nymphs (juveniles) are similarly coloured, but smaller and spiny in appearance, and they undergo a number of moults before they reach maturity.
Lace bugs congregate on the undersides of azalea and rhododendron leaves. There they suck out the sap, robbing the plant of nutrients and causing the leaves to turn speckled grey-brown or silvery. The nymphs excrete honeydew, a sugary liquid on which sooty mould develops. If this coating becomes dense it decreases photosynthesis, further reducing the plant’s health.
The damage is similar to that caused by thrips. To find out whether lace bugs are the cause, beat the affected foliage over a white cloth or paper where any insects that fall can be seen easily. Cast skins shed by the nymphs are another clue to lace bugs’ presence.
Management and control
To avoid over-use of chemicals, try to exercise tolerance whenever possible. A little damaged foliage can be pruned, and minor occurrences of lace bug do not harm the plant seriously. Often the general condition of the plant is the factor that determines the scale of attack, making an azalea growing in a hot sunny location, where it suffers water stress, more vulnerable than a plant growing in the shade.
In the event of heavy infestations, spraying azaleas with a systemic insecticide – which the bugs ingest when they suck the sap – is effective but timing is crucial. Lace bugs do not travel far or fast and it takes a long while for them to reach harmful numbers. So, provided the spray is timed correctly, a single treatment should be enough to kill a localised infestation and prevent a recurrence for one or maybe even two years.
Lace bugs go through several generations during summer, so spraying the azaleas then is futile because eggs are constantly hatching. However, eggs laid in autumn lie dormant over winter and hatch in spring. The new season’s nymphs do not emerge all at one moment, so spraying too early will kill only the first of them. But one application of a systemic insecticide containing imidacloprid or acetamiprid in late to mid spring will kill the later emerging nymphs as well as the earlier ones before they reach adulthood.
An organic control is horticultural soap.
Source – Will Hudson and Kris Braman, UGA Extension Entomologists
Azalea lacebugs overwinter as eggs and hatch in the spring. Early spring is a good time to control them before they become too numerous.
Azalea lace bug attacks azaleas and some rhododendrons. Azalea lace bugs mainly feed on the undersides of the leaves, leaving the top of the leaf with white to yellow stippling or flecking. Heavy lace bug feeding on azalea can reduce plant vigor and flowering and affects the overall look of the plant.
Adult azalea lace bugs are 1/8 inch long. The transparent wings are held flat on the back. Their wings are lacy with two grayish-brown cross-bands connected in the middle. Nymphs begin life clear but quickly turn black and spiny. The flask-shaped eggs are partially embedded in leaf tissue, usually on the bottom of the leaf, and often are covered with a black tar-like secretion.
Look for the first signs of damage on plants in full sun or in protected areas beginning in March and continuing throughout the summer. Lace bugs overwinter as eggs. There are four generations a year. Lace bug adults and nymphs live and feed on the underside of leaves. Look for white stippling on older leaves. Look under leaves to find lace bug life stages and black fecal spots. On azaleas with a lot of damage, the top of the leaf can become grey or silvery.
Azaleas can withstand a lot of lace bug injury without much reduction in growth or bloom. The damage however on the leaves is unsightly. Control is generally recommended for the spring when insects are few in numbers. Treating early also protects the new leaves from damage from these insects. Once a leaf is damaged, the injury will be visible until the leaf falls off the plant.
Time spring insecticide applications for the presence of the first generation nymphs, usually with the early warm weather in late February in south Georgia through March and April in central and north Georgia.
Late summer insecticide applications are also helpful. Lacebugs overwinter as eggs and managing adults now reduces the number of eggs on plants and the number of lacebugs you will see next spring. Once lacebugs are in the egg stage, insecticides will not effectively manage them.
Cultural controls for azalea lace bugs
- Plant azaleas only in partial shade. Too much sun stresses the plant and can make lace bug injury worse.
- Keep plants healthy with proper planting, fertilizing and watering.
- One of the best things you can do is scout azaleas (particularly early in the season) to identify and control infestations before numbers increase and leaf damage is severe.
Contact insecticides include the pyrethroids (bifenthrin, cyfluthrin, cypermethrin, permethrin, etc.) and carbaryl (Sevin and others) as well as other insecticides.
- The biggest concern with contact insecticides is getting full coverage. The chemical must be applied to the underside of the leaves. This is difficult with larger, fuller plants.
- You may need to make more than one application for full control. Check plants three to four weeks after the first application to see if they need another treatment. Knocking the branches over a white piece of paper should dislodge the lace bugs and make them easier to see.
- Some systemic insecticides may be used as soil applications (liquid drenches and granular treatments) as well as sprays. Soil applied insecticides enter through the root system and then travel into the leaves.
- Foliar sprays of systemic insecticides tend to work more quickly than soil application but soil applications give a longer residual control – up to several months.
- Even though some soil applied systemic insecticides may take two weeks or longer to become active in the leaves of large plants, this is not a problem if plants are small or if application is made early enough in the season to provide protection for the first flush of new leaves.
- Read and follow all label directions since systemic insecticides differ in the way they work in the plant.
For more information:
For pest management information see the Pest Management Handbook (Follow all label recommendations when using any pesticide)
Control of Lace Bugs on Ornamental Plants