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Pest SolutionsPESTS + WEEDSUSING PESTICIDES OR HERBICIDES?
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Azalea Lace Bugs
Stephanitis pyrioides
Updated Oct 10, 2024
Make a Positive Identification
- Azalea lace bugs are tiny, winged insects that feed on the lower leaf surface of azalea and rhododendron plants.
- Adults and nymphs cause many white and yellow dots that damage the upper leaf surface. Leaf stippling describes the damage caused by piercing and sucking insect mouth parts.
Species: Azalea Lace Bugs
Signe Danler, Oregon State University
Azalea lace bugs suck the sap, which damages leaf tissue. This causes white or yellow stippling damage on the upper leaf surface.
Species: Azalea Lace Bugs
Robin Rosetta, Oregon State University
Nymphs and fecal spots are visible on the underside of an azalea leaf.
Species: Azalea Lace Bugs
Photo credits
Left:
Robin Rosetta, Oregon State University
Right:
Whitney Cranshaw, Colorado State University, Bugwood.org
Severe damage turns rhododendron leaves yellow (left photo) and even white (right photo).
Species: Azalea Lace Bugs
Tracy Wootten, University of Delaware, Bugwood.org
Azalea lace bug nymphs and adults feed on leaves. They are tiny. Use a magnifying glass to see them.
LOOK-ALIKE: IRON DEFICIENCY
Species: Iron deficiency
Neil Bell, Oregon State University
Iron deficiency due to high soil pH causes yellow leaves with green veins (chlorosis). This deficiency looks similar to azalea lace bug feeding damage. Look for fecal spots on the lower surface of leaves to distinguish azalea lace bug damage.
Different risks or methods
Acidify soil pH by adding elemental sulfur to the soil. Use fertilizers specific to rhododendrons and azaleas. These methods help change the soil pH and make iron available to plants.
Azalea Lace Bugs Benefits
- Azalea lace bugs are a food source for insect predators such as green lacewings.
Azalea Lace Bugs Risks
- Azalea lace bugs suck sap and damage leaves.
- They cause yellow stippling on the upper leaf surface, which is unattractive.
- Their feeding reduces plant vigor.
Risk Card
Does it cause harm?
Adults & Children
None
Property
Some
Damage azalea & rhododendron plants
Pets
None
Annoyance
Some
Depends on your tolerance for insect damage
Environment
None
Food source for insect predators such as green lacewings
Action Optional
TAKE ACTION?
Minor azalea lace bug damage is unsightly. Severe damage weakens and kills plants.
Do I need to take action?
- You may ignore minor damage. It could get worse each year.
- Damaged leaves remain on the plant until they fall off or are removed.
- For severely damaged plants, consider removing the plant. The ‘Encore’ series of azalea varieties have shown resistance to azalea lace bug feeding. Or install plants that are less prone to pest problems.
What if I do nothing?
Severe infestations may kill azalea and rhododendron bushes.
Prevent Azalea Lace Bugs
Signe Danler, Oregon State University
Keep Plants Healthy
- Stressed plants are more susceptible to insect feeding that results in damage.
- Amend the soil with compost before planting. Provide water and fertilizer as needed. Mulch the soil to conserve moisture for plant growth.
- Grow rhododendrons and azaleas partly in shade. Planting them in full sun will stress these plants.
Robin Rosetta, Oregon State University
Watch for Azalea Lace Bug Damage & Insects
- In winter, look for brown, crusty patches on leaf surfaces. The patches conceal eggs.
- In the Pacific Northwest, azalea lace bug activity starts in early May and continues through the summer. Nymphs are semi-transparent, as shown in the photo.
- Look for leaf stippling damage on the mature leaves first, then small, newer leaves.
"NEW shipment of Encore Azaleas!" by The Greenery Nursery and Garden Shop is licensed under CC BY 2.0.
Plant-Resistant Varieties
- The ‘Encore’ series of azalea varieties have shown resistance to insect feeding. The photo shows a selection of ‘Encore’ varieties at a nursery.
- Rhododendrons, R. canescens and R. periclymenoides cultivars ‘Micrantha,’ ‘Red Slipper,’ ‘Lavender Twist,’ and others show varying insect-feeding resistance.
John Ruter, University of Georgia, Bugwood.org
Plant Different Shade-Tolerant Shrubs (bushes)
- Replace rhododendrons and azaleas infested by azalea lace bugs with other shade-tolerant flowering shrubs.
- Native Oregon grape (Berberis spp.) is a good substitute. Or plant non-native hydrangea (shown in the photo), Camellia, Osmanthus, Daphne, or Kalmia. These plants are less vulnerable to insect pests.
SOLUTIONS FOR AZALEA LACE BUGS
Monitoring & Timing
- Inspect plants weekly for signs of azalea lace bug starting in mid to late spring
- Look for nymphs on the underside of leaves.
- Begin treatment when you see them crawling. Action early in the season limits their numbers as the season progresses.
Non-chemical Methods
- Encourage azalea lace bug predators such as green lacewings. Planting flowers to attract aphid predators is a preventive strategy. See Biological Pest Control Methods.
- Spray azalea lace bugs off plants with a strong stream of water.
Insecticides (Insect Killers)
- Insecticides effectively control azalea lace bugs when used according to the label instructions.
NEED HELP?
Consider a licensed pest control company. Learn How to Hire a Pest Control Company.
Your local Extension Specialist in Oregon and other states can suggest other methods.
Jump to
| Method | Does it work? | Is it safe? | Recommendation |
|---|---|---|---|
A Attract Lace Bug Predators |
Effective |
Low risk |
Recommended |
B Spray Plants with a Strong Stream of Water |
Somewhat effective |
Low risk |
Recommended |
C Control with Insecticides |
Effective |
Moderate risk |
Use if Necessary |
|
D If Using Insecticides, Protect Yourself & Minimize Risks
|
A
Attract Lace Bug Predators
Non-Chemical Method
Attract Lace Bug Predators
Recommended
Natural enemies such as green lacewings feed on azalea lace bugs and other insects. The photo shows a green lacewing larva, which eats azalea lace bug.
| Does it work? | Effective
|
| How much effort? | Moderate effort Include trees, shrubs, and flowers that attract wildlife and natural enemies in your landscape. |
| What's the risk? | Low risk |
| Possible risk of exposure or harm from chemicals | NONE |
Whitney Cranshaw, Colorado State University, Bugwood.org
B
Spray Plants with a Strong Stream of Water
Non-Chemical Method
Signe Danler, Oregon State University
Spray Plants with a Strong Stream of Water
Recommended
A strong stream of water directed at the lower leaf surface of infected plants removes or injures feeding insects.
| Does it work? | Somewhat effective Use preventive measures for best results. |
| How much effort? | Moderate effort |
| What's the risk? | Low risk |
| Possible risk of exposure or harm from chemicals | NONE |
C
Control with Insecticides
Chemical Method: Use with caution
iStock
Control with Insecticides
Use if Necessary
- Insecticides can effectively control azalea lace bugs when used according to label instructions.
- If you choose to use insecticides, also use monitoring and prevention.
- Insecticides can also have an impact on beneficial insects such as bees and azalea lace bug predators.
| Does it work? | Effective
|
| How much effort? | Moderate effort
|
| What's the risk? | Moderate risk Using insecticides comes with real risks. ALWAYS read the entire label front to back. Review instructions even for brands you know. |
| Possible risk of exposure or harm from chemicals | El uso de pesticidas conlleva cierto grado de riesgo. El riesgo más bajo se produce sin el uso de pesticidas. You may be exposed to a pesticide if you:
Follow directions closely to reduce risk. |
Some insecticides are available for home use. A few are listed below. These active ingredients are suggested chemical treatments to control azalea lace bug. Look for these chemical names in the “Active Ingredients” section of product labels.
- Mineral oil
- Potassium laurate (potassium salts of fatty acids)
- Imadicloprid (a systemic Neonicotinoid)
- Pyrethrin with sulfur
Suggested active ingredients are from the Pesticide Information Center Online (PICOL) Database. They are permitted for HOME use in Oregon. Read the label for application directions and effectiveness information.
ONLY professional pesticide applicators can use Restricted-Use Pesticides (RUP) that may be more effective. If you need further support, contact a licensed pesticide applicator.
NEONICOTINOIDS
Imidacloprid is an example active ingredient in this group of insecticides.
Neonicotinoid insecticides can harm pollinators and natural enemies. Following application, the poison may be found in flowers for months or years. Beneficial insects feed on the nectar and pollen. For more information, see OSU’s How to Reduce Bee Poisoning from Pesticides
Application Tips
CONTACT INSECTICIDES
- Must contact azalea lace bugs to kill them. Thorough coverage is required.
- Apply in the spring when you see azalea lace bug nymph activity. Repeat as needed.
- Read the label carefully for application and frequency details.
- Some insecticides are highly toxic to bees. Do not spray onto blooming crops. Do not allow to drift onto blooming crops or weeds when bees are active.
- Using insecticides comes with real risks. ALWAYS read the entire label front to back. Review instructions even for brands you know.
SYSTEMIC INSECTICIDES (NEONICOTINOIDS)
- Systemic insecticides are absorbed by one plant part such as stems or roots.
- Then it moves to leaves or other plant parts where pests feed.
- May be applied as a soil drench in spring. Adequate rain or irrigation are required to move it through the soil to the roots.
- A single application may provide season-long control when applied according to the label directions.
Neonicotinoid insecticides can harm pollinators and natural enemies. Following application, the poison may be found in flowers for months or years. Beneficial insects feed on the nectar and pollen. For more information, see OSU’s How to Reduce Bee Poisoning from Pesticides
If Using Insecticides, Protect Yourself & Minimize Risks
Chemical Method: Use with Caution
Brandon (@greener_30) on Unsplash
Why Is It important to Read Insecticide Labels?
- They have detailed information on how to use the product correctly and legally.
- They contain information on potential hazards of the product.
- They provide instructions you should follow for poisonings and spills.
- Following label instructions helps you to minimize the risks and maximize the benefits.
Key Safety Tips
- Read the entire label front to back.
- Follow the instructions.
- Review the instructions even for brands you know.
- Only apply the product where the label says it may be applied.
- Keep all insecticides in their original container.
The Label is the Law
ALWAYS read the label before using herbicide products. The label is a legal document that provides information on how to safely use the herbicide. This helps avoid harm to human health and the environment. Using an herbicide in off-label ways is illegal. It can result in legal enforcement actions.
READ THE LABEL & Follow Instructions
It has instructions to protect you and the environment.
- Labels are different for every product and they often change over time.
- Use a magnifying glass for small print.
- Pay attention to CAUTION, WARNING, and DANGER statements.
- Pay attention to the PRECAUTIONARY STATEMENTS.
- The law states you must read and follow herbicide instructions.
Protect Yourself
Eye, skin, & lung irritants
- Wear gloves, safety glasses, a long-sleeve shirt, pants, socks, and shoes.
- Avoid contact with eyes, skin, or clothing.
- Wash hands after mixing or applying, and before eating or smoking.
- Never spray directly overhead. Pay attention to wind conditions.
Protect Children & Pets
Keep out of the reach of children.
- Keep children and pets away from the application area.
- Remove toys and pet dishes from the area before applying insecticides. Wait until spray has dried or dust has settled.
Protect Pollinators
Many insecticides are extremely toxic to bees.
- Honey bees and other pollinators are harmed by most insecticides.
- Don’t spray on bees or other flying insects.
- Don’t allow spray to contact blooming plants.
Avoid Wet Weather & Keep Insecticides Out of Waterways
Some insecticides are toxic to fish and aquatic invertebrates.
- Don’t spray insecticides in water.
- Insecticides sprayed on plants can wash off with rain and enter waterways.
Storage & Disposal
- Store out of the reach of children and pets.
- Store in a cool and dry place.
- Never pour down any drain.
- If you mix too much, apply it rather than storing it.
- Don’t put pesticide containers in the trash unless instructed by the label.
- Take unused insecticides to a hazardous waste facility.
Call 1-800-CLEANUP (1-800-253-2687) to find out where to dispose of pesticides.
For the Portland metro region in Oregon, contact Metro’s Recycling Information. Call 503-234-3000, email or visit Metro’s website
More about:
About Using Pesticides on School Grounds in Oregon
If using pesticides on school grounds, there are special rules in Oregon. See School Integrated Pest Management (Oregon Department of Agriculture).
NEED HELP?
The National Pesticide Information Center (NPIC) can answer questions about pest control chemicals.
1-800-858-7378 or npic@ace.orst.edu
Consider using a licensed pest or weed control company. Learn How to Hire a Pest Control Company.
Your local Extension Specialist in Oregon and other states can suggest other methods.
Content provided by writer Signe Danler and by editor Weston Miller. Pesticide safety information edited by Kaci Buhl.
Peer review facilitated by OSU Department of Horticulture.
AZALEA LACE BUG REFERENCES
Azalea (Rhododendron): Azalea and Rhododendron Lace Bug
PNW Insect Management Handbook
How to Manage Pests in Gardens and Landscapes: Lace Bugs
University of California IPM
Lace bugs: Life Cycle, Monitoring, and Pest Management in New Jersey (PDF)
Rutgers NJAES Cooperative Extension