Lace bugs are a persistent threat to trees and ornamental plants such as azaleas, oaks, hawthorns, and sycamores. Their feeding activity causes stippling, discolored spots, bleaching of upper leaf surfaces, and in severe cases, premature leaf drop, reducing plant vigor and compromising the health and aesthetics of the tree or plant.
Susceptible Hosts
Many species of trees & shrubs. Common plants:
- Azalea (Rhododendron)
- Hawthorn (Crataegus)
- Oak (Quercus)
- Serviceberry (Amelanchier)
- Sycamore (Platanus)
Signs of Damage
- Discolored spots, stippling, and bleaching of upper leaf surface.
- Black fecal deposits on underside of leaf.
- Crown thinning and leaf drop in severe cases./li>
Physical Appearance
- Adults are 1/8” (3mm) to 1/10” (1.5mm) long and have transparent lace-like wings.
- Nymphs begin colorless.
Biology / Lifecycle
- Depending upon species, over-wintering eggs hatch (e.g., azalea lace bug) or adults become active (e.g., hawthorn lace bug) as new leaves emerge in spring.
- Eggs are laid along leaf veins and pubescence.
- Nymphs go through 5 instar stages before becoming adults, which can take 5-7 weeks.
- In late summer or early fall, the primary infections produce secondary spores and create new infections, which can continue through the growing season during wet periods.
- Up to 5 generations per year.
Lace bug damage on top side of leaf
Adult lace bug on under side of leaf
Fecal spots on under side of leaf
Treatment Strategy/Expectations
Early detection is the key in reducing infestations. When natural enemies, like the lady beetle, are not sufficient in keeping the population in check, insecticides are very effective for controlling aphids. Soil and bark spray applied systemic insecticides are very effective. Use Transtect Infusible or Xytect 10% as a tree injection treatment for trees that cannot be treated with foliar sprays or other systemic options.
Cultural treatments (e.g. root collar excavation, proper irrigation, soil management, etc.) need to be considered to improve/maintain plant health.
| Product | App. Method | Dosage | Timing | Re-Treatment | GDD/Phen. |
| Soil application Lower systemic bark spray | 1 packet/5-17 inches DBH, or 10-17 feet shrub height 6 packets/1 gal water apply 1.5-2.0oz solution/ 1 inch DBH | Any time during the season, ideally 1-3 weeks prior to feeding and after full leaf emergence | Annually | As new growth appears | |
| Tree injection | Refer to label for rates. Varies based on tree size | Any time during the season, ideally 1-3 weeks prior to feeding and after full leaf emergence | Annually | As new growth appears | |
| Tree injection | Refer to label for rates. Varies based on tree size | Any time during the season, ideally 1-3 weeks prior to feeding and after full leaf emergence | Annually | As new growth appears | |
| Soil injection | 0.2 oz per inch DBH < 15” 0.4 oz. per inch DBH >15” | Any time during the season, ideally 1-3 weeks prior to feeding and after full leaf emergence | 30-45 days | As new growth appears | |
| Soil application | 0.1-0.2 oz./inch DBH | Fall or Spring when soil is not frozen | Annually | - |
Product is Rainbow Ecoscience’s industry standard recommendation for most industry situations.
N – Neonicotinoid Product
Reach out to Rainbow Ecoscience Technical Support for additional protocol support.
Trunk injection with Quantum
Soil application with HTI 2000
Lower systemic bark spray
Always refer to product label for rates and approved uses. Some images courtesy of forestryimages.org or Wikimedia Commons. Use of the images does not imply endorsement of treatments.
