Rhododendron Lace Bug
Stephanitis rhododendri
110 host plants
Last updated
On rhododendron leaves, look for pale stippling on upper surfaces with dark, varnish-like tar spots covering the undersides; this is the hallmark of Stephanitis rhododendri feeding. Nymphs are spiny, dark, and develop through four growth stages while clustering among their own dark fecal spots. By mid-July, heavily infested leaves appear severely yellowed or whitened.
Scout undersides of leaves in early July for the first visible damage. Reduce nitrogen fertilizer to decrease plant attractiveness. Horticultural oil with thorough undersurface coverage suppresses all life stages if applied early. Bifenthrin or malathion provide stronger control, though oils are preferred.
Quick Reference
Order
Hemiptera
Type
sucking-insect
Host Plants
110
Peak Activity
Damage visible early to mid-July. source: WSU HortSense
Damage Severity
cosmetic
Monitoring & Action
How to Monitor
Inspect leaf undersides of rhododendrons (not azaleas) from late spring onward. Look for pale nymphs and black fecal deposits. If lace bug damage is found on azaleas, the species is S. pyrioides, not S. rhododendri.
When to Act
No published threshold. Treat when nymphs are visible on multiple shoots. Damage is almost never fatal, so tolerance is often the best approach for light infestations. source: WSU HortSense
What Damage Looks Like
Feeding produces stippled, yellowed upper leaf surfaces. Leaves appear sickly and chlorotic. Black fecal deposits ('tar spots') visible on leaf undersides. Damage usually apparent by early to mid-July. Almost never fatal, but chronically infested plants look yellowed and unhealthy. source: WSU HortSense
Cultural Controls
- Some spiders, assassin bugs, and minute pirate bugs provide natural population control. WSU HortSense
- Hand removal of adults and nymphs on a regular basis limits visible damage. WSU HortSense
- Direct a strong stream of water at leaf undersides to dislodge nymphs; wingless nymphs cannot return. WSU HortSense
- Site rhododendrons in partial shade to reduce damage severity.
Host Plants (110)
Rhododendron 'Alice' Alice Rhododendron Rhododendron 'Anah Kruschke' Anah Kruschke Rhododendron Rhododendron 'Anna Rose Whitney' Anna Rose Whitney Rhododendron Rhododendron 'Argosy' Argosy Rhododendron Rhododendron 'Bruce Briggs' Bruce Briggs Rhododendron Rhododendron 'Capistrano' Capistrano Rhododendron Rhododendron 'Carmen' Carmen Rhododendron Rhododendron 'Cheer' Cheer Rhododendron Rhododendron 'Cilpinense' Cilpinense Rhododendron Rhododendron 'Crest' Crest Rhododendron Rhododendron 'Cunningham's White' Cunningham's White Rhododendron Rhododendron 'Cynthia' Cynthia Rhododendron Rhododendron 'Dora Amateis' Dora Amateis Rhododendron Rhododendron 'Dreamland' Dreamland Rhododendron Rhododendron 'Elizabeth' Elizabeth Rhododendron Rhododendron 'Fantastica' Fantastica Rhododendron Rhododendron 'Gibraltar' Gibraltar Azalea Rhododendron 'Girard's Fuchsia' Girard's Fuchsia Azalea Rhododendron 'Glacier' Glacier Azalea Rhododendron 'Goldflimmer' Goldflimmer Rhododendron Rhododendron 'Gomer Waterer' Gomer Waterer Rhododendron Rhododendron 'Hallelujah' Hallelujah Rhododendron Rhododendron 'Hino-Crimson' Hino-Crimson Azalea Rhododendron 'Horizon Monarch' Horizon Monarch Rhododendron Rhododendron 'Hotei' Hotei Rhododendron Rhododendron 'Jock' Jock Rhododendron Rhododendron 'Klondyke' Klondyke Azalea Rhododendron 'Lee's Dark Purple' Lee's Dark Purple Rhododendron Rhododendron 'Lord Roberts' Lord Roberts Rhododendron Rhododendron 'Mandarin Lights' Mandarin Lights Azalea Rhododendron 'Moonstone' Moonstone Rhododendron Rhododendron 'Mother's Day' Mother's Day Azalea Rhododendron 'Nancy Evans' Nancy Evans Rhododendron Rhododendron 'Nova Zembla' Nova Zembla Rhododendron Rhododendron 'P.J.M.' P.J.M. Rhododendron Rhododendron 'Peekaboo' Peekaboo Rhododendron Rhododendron 'Percy Wiseman' Percy Wiseman Rhododendron Rhododendron 'Pohjola's Daughter' Pohjola's Daughter Rhododendron Rhododendron 'Purple Gem' Purple Gem Rhododendron Rhododendron 'Ramapo' Ramapo Rhododendron Rhododendron 'Rosamundi' Rosamundi Rhododendron Rhododendron 'Roseum Elegans' Roseum Elegans Rhododendron Rhododendron 'Sappho' Sappho Rhododendron Rhododendron 'Solidarity' Solidarity Rhododendron Rhododendron 'Stewartstonian' Stewartstonian Azalea Rhododendron 'Taurus' Taurus Rhododendron Rhododendron 'The Honourable Jean Marie de Montague' Jean Marie Rhododendron Rhododendron 'Trilby' Trilby Rhododendron Rhododendron 'Unique' Unique Rhododendron Rhododendron 'Vulcan' Vulcan Rhododendron Rhododendron 'Winsome' Winsome Rhododendron Rhododendron 'Yaku Prince' Yaku Prince Rhododendron Rhododendron 'Yaku Princess' Yaku Princess Rhododendron Rhododendron alabamense Alabama Azalea Rhododendron arboreum subsp. cinnamomeum Cinnamon Rhododendron Rhododendron augustinii Augustine Rhododendron Rhododendron auriculatum No common name (R. auriculatum) Rhododendron bibiani Bibiani Rhododendron Rhododendron bureavii Bureau Rhododendron Rhododendron campylocarpum subsp. coloxanthum Coloxanthum Rhododendron Rhododendron catawbiense Catawba Rhododendron Rhododendron cinnabarinum Cinnabar Rhododendron Rhododendron concinnum Concinnum Rhododendron Rhododendron daphnoides Daphnoides Rhododendron Rhododendron dauricum Dauricum Rhododendron Rhododendron davidsonianum Davidsonianum Rhododendron Rhododendron falconeri subsp. falconeri Falconer Rhododendron Rhododendron formosum var. formosum Formosum Rhododendron Rhododendron forrestii subsp. forrestii Forrest Rhododendron Rhododendron fortunei subsp. discolor Fortune Discolor, Discolor Rhododendron Rhododendron groenlandicum Labrador-tea, Labrador Tea Rhododendron haematodes subsp. haematodes Haematodes Rhododendron Rhododendron hanceanum Hanceanum Rhododendron Rhododendron hippophaeoides var. hippophaeoides Hippophaeoides Rhododendron Rhododendron hodgsonii Hodgson Rhododendron Rhododendron irroratum Irroratum Rhododendron Rhododendron johnstoneanum Rhododendron, johnstoneanum Rhododendron keiskei Keiskei Rhododendron, Keisuki Rhododendron Rhododendron kiusianum Kiusianum Azalea, Kyushu Azalea Rhododendron lacteum Lacteum Rhododendron Rhododendron luteiflorum Luteiflorum Rhododendron Rhododendron lutescens Lutescens Rhododendron Rhododendron luteum Pontic or Pontica Azalea Rhododendron macabeanum Macabeanum Rhododendron Rhododendron macrophyllum Pacific Rhododendron Rhododendron mucronulatum Rhododendron, mucronulatum Rhododendron myrtifolium Myrtifolium Rhododendron Rhododendron niveum Niveum Rhododendron Rhododendron occidentale Western Azalea Rhododendron orbiculare subsp. orbiculare Obiculare Rhododendron Rhododendron oreotrephes Oreotrephes Rhododendron Rhododendron pachytrichum Pachytrichum Rhododendron Rhododendron ponticum Rhododendron, ponticum Rhododendron prinophyllum Roseshell Azalea, Pinkshell Azalea Rhododendron prunifolium Plumleaf Azalea Rhododendron quinquefolium Quinquefolium Azalea Rhododendron racemosum Racemosum Rhododendron Rhododendron roxieanum var. oreonasters No common name Rhododendron rubiginosum Rubiginosum Rhododendron Rhododendron schlippenbachii Royal Azalea Rhododendron serpyllifolium Wild Thyme, Azalea Rhododendron serpyllifolium var. albifolrum White Wild Thyme, Azalea Rhododendron sinofalconeri Sinofalconer Rhododendron Rhododendron sinogrande Sinogrande Rhododendron Rhododendron smirnowii Smirnow Rhododendron Rhododendron stenopetalum Rhododendron, stenopetalum Rhododendron thomsonii subsp. thomsonii Thomson Rhododendron Rhododendron wardii Ward Rhododendron Rhododendron wiltonii Wilton Rhododendron Rhododendron yakushimanum Yak Rhododendron
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— Chris Welch, ISA Certified Arborist
Sources & References
Data Maturity Baseline Extension data. Expert review underway.