Native to Japan, the azalea lace bug, Stephanitis pyroides, was introduced to the United States in the early 1900’s by the movement of its host species, azaleas. The azalea lace bug has become a destructive pest to azaleas in the eastern United States. This bug causes damage by sucking out the fluid of the leaves from the underside. This feeding creates injury to foliage including yellow to brownish speckling on the upper leaf surface. Severe injury may result in early leaf drop.
Treatment Strategy
Azalea lace bug eggs hatch in early spring and the nymphs begin feeding on the underside of leaves. Soil applications of Xytect or Transtect will provide a high level of control and are the recommended products of choice. Apply Xytect in late summer/early fall for next year control or apply Transtect in early spring to ensure high titer levels are within the tree at the time the nymphs emerge. Arborists should only use foliar sprays for immediate activity against the insect. Thorough coverage on the underside of the leaves is essential for good control when applying foliar products.
Other Treatment Practices
- Maintain plant health and monitor closely for this insect.
- Adequate water is a key factor in maintaining stress free plants. A slow, deep watering event once every few weeks during dry conditions will help maintain soil moisture levels and minimize stress.
- Mulch is very beneficial for all trees because it reduces competition with turf and moderates soil temperature and moisture levels. The addition of 3 inches of wood chips or shredded bark under the drip line can have a very beneficial effect by holding in moisture and promoting healthy fibrous roots.
- Cambistat can be also be used to promote tree health and reduce the incidence and severity of stress Plant lace bug susceptible host plants in areas of the landscape that are shady. Lace bugs tend to prefer host plants in bright, sunny areas. A hard jet of water from a garden hose can dislodge the young nymphs after hatching in the spring.
Soil Application or Limb/Foliar Spray Using Transtect
Soil Application or Limb/Foliar Spray Using Xytect 2F
Soil Application or Limb/Foliar Spray Using Xytect 75WSP
Limb/Foliar Spray Using RTSA Horticultural Oil
Expected Results
Xytect and Transtect will provide a high level of control vs. lacebugs. Insecticides will not restore an undamaged appearance, but can reduce or prevent further damage. Lacebug activity results in a large amount of debris on the undersides of leaves, this can often be mistaken for lack of control, do not mistake this for lack of performance. Almost any insecticide will control lace bugs if it is sprayed directly onto the insect, however thorough coverage on the underside of the leaf is required. Multiple spray applications may be required as well, making soil applications the product recommendations of choice.
Signs of Damage
- Discolored spots or bleaching of the upper leaf surface
- Leaves can become whitish, dry up, and fall off in severe infestations
- The adult is 1/8 inch (3mm) long with light brown legs and antennae
- The wings are transparent and lace-like with brown and black markings
- Nymphs may be found on the underside of the leaf surface
- Nymphs are colorless as they emerge, but soon turn black and spiny
- Deposits of hard, dark, varnish-like spots of excrement may be found on underside of the leaf surface, especially along the leaf veins where the female inserts her eggs
- Eggs are white, smooth, and flask shaped with a neck to one side
Photo: Jim Baker
North Carolina State University, Bugwood.org
Photo: Pest and Diseases Image Library, Bugwood.org
Photo: Jim Baker
North Carolina State University, Bugwood.org
Trees At Risk
Azalea (Rhododendron spp.) Andromeda lacebugs are quite similar in appearance and the treatments are the same for both pests.
Biology
- Nymphs hatch in early spring (448-618 GDD, when pieris blooms begin to fade) and begin feeding on the underside of the leaves before molting 5 times as they become adults.
- Adults mate and the females lay eggs in the tissue on the underside of the leaves along the veins by mid-summer. 2nd Generation emerges 802-1029 GDD.
- Depending on location, there may be a third generation that occurs in late summer or early fall.
- Two or more generations occur. There are 4 generations in Maryland.
- The eggs of the last generation overwinter in the egg stage on the underside of the leaves along the veins.
References
University of Florida
https://entnemdept.ufl.edu/creatures/orn/shrubs/azalea_lace_bug.htm
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.
