Azalea lace bugs can be very destructive pests. They have piercing-sucking mouth parts in both nymph and adult life stages. This damage causes the azalea’s foliage to appear gray, pale colored specking. When damage is severe enough, the whole leaf appears white and drops early. The early leaf drop can make the azalea susceptible to some dieback diseases.
Lace bugs overwinter as eggs. The adult female lace bug inserts her eggs into the leaf tissue and will cover them with a dark splotch of varnish-like material to seal the egg into the leaf. There are generally three or more generations of lace bugs in South Carolina per year.
Lace bugs are about 1/8-inch long and have dark markings on the back and wings that make them hard to see when on the leaf. The nymphs (immature forms) are colorless at first, but turn black over time. Nymphs can have a number of spines on their backs.
Control of lace bugs on azaleas begins with planting resistant varieties. The following azalea cultivars have resistance to azalea lace bug: ‘Dawn,’ ‘Pink Star,’ ‘Ereka,’ ‘Cavalier,’ ‘Pink Fancy,’ ‘Dram,’ ‘Seigei,’ ‘Macrantha,’ ‘Salmon Pink,’ ‘Elsie Lee,’ ‘Red Wing,’ Sunglow’ and ‘Marilee.’
Lace bugs can be managed by different methods. The best preventative measure to make sure you are growing healthy plants in the optimal location. Azaleas grow best in the morning sun with afternoon shade. Azaleas grown in full sun become stressed and can secrete compounds that lace bugs can detect. This enables the lace bugs to target weaker plants. Choosing the correct planting site and maintaining proper fertility based on soil test recommendations will go a long way in preventing future problems.
The lace bug does face a few natural enemies including parasitic wasps, predatory assassin bugs, lacewing larvae, lady beetles, jumping spiders, pirate bugs, and mites. Avoid using broad-spectrum insecticides (like Seven dust) and plant native perennials to attract beneficial insects to the landscape.
Horticultural oils and insecticidal soaps are very effective in controlling lace bugs. However, these two products must directly coat the lace bug’s exoskeleton to suffocate them. Oil and soap sprays have no residual effect, so beneficial insects are not harmed once the spray has dried.
There are two synthetic chemical controls methods used for lace bugs: systemic and non-systemic. Systemic pesticides are usually taken up by the plant’s roots and distributed throughout the plant’s tissues. When the insect feeds on the plant’s tissues, it ingests the product and kills the bug. Systemic insecticides that contain the active ingredient imidacloprid or dinotefuran are effective in controlling lace bugs. Azaleas should be sprayed when the first lace bugs appear and a second application in seven to ten days to control and newly hatched lace bugs. Good control of the first generation in March to May will greatly reduce problems later in the season. Control of second (July to August) and later generations (September to October) may be necessary.
Non-systemic insecticides kill insects when they come into contact with the chemical during or after the application. Products with the active ingredient organophosphate (malathion) and pyrethroid (bifenthrin and permethrin) are also effective in controlling lace bugs.
These chemicals can also kill or repeal natural enemies and beneficial insects. Always read and follow all label directions before using a pesticide.
For more information on lace bugs, please visit the Home and Garden Information Center website at hgic.clemson.edu. Tune in on Tuesday nights to watch “Making it Grow” at 7pm on SCETV or mig.org. Email Outen at callenb@clemson.edu.
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