Larvae of the green lacewing have shown prom- ise as a biological control agent. In a nursery study, purchased green lacewing larvae released against newly hatched azalea lace bug nymphs resulted in 79-97% control.
2. Biorational pesticide control
hatch. If needed, follow with a second applica- tion a week later (if insects are still present). Note that if the first generation is controlled, subse- quent sprays may not be necessary during the remainder of the season. Continue to monitor, looking for live lace bugs and objectionable damage before spraying.
Insecticidal soap and horticultural oil will control lace bugs, but to be effective, must contact them directly on the underside of the foliage. Insecti- cidal soap has a short residual and may require repeat applications. Azalea lace bug populations have been reduced 88-91% by thoroughly cover- ing the underside of foliage with insecticidal soap. Horticultural oil is effective as a direct contact treatment on active lace bugs, and will also kill some eggs. Oil can be used as a dormant spray (3%) or during the growing season (1%).
a) contact sprays
Lace bugs may be may be controlled with con- tact insecticides, including Permethrin, Cyfluthrin (Tempo 2), Scimitar, and carbaryl (Sevin). The spray must be directed toward the underside of leaves, however, or control will be inadequate. Doing so on small to medium plants can be a formidable task, notwithstanding the danger to the applicator. Additionally, these contact pesticides may kill any beneficial in- sects present.
Neem oil (azadirachtin) acts as a feeding inhibi- tor, an insect growth regulator, or both. Research in Maryland showed a 50% reduction in azalea lace bugs after a Neem application.
3. Chemical Control
Most insecticides, except for horticultural oil, are not effective on the egg stage of the lace bug, so preventive sprays are useless. Therefore, it is important to monitor first to make sure that the insect is indeed present before spraying. Insecti- cides should be applied 7 to 10 days after eggs
b) systemic sprays
In general, systemic insecticides will give better control with less precise technique. Acephate (Orthene) gives excellent lace bug control when used according to label instructions. Spray di- rectly onto foliage when lace bugs are present. Imidacloprid (Merit) is labeled for use by profes- sional landscapers as either a foliar treatment (apply 6 to 8 weeks prior to egg hatch) or soil treatment (drench or injection; apply in late fall or early winter).
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