Azalea Lace Bug Diagnostic Guide
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.
Shrubs at Risk
Azaleas are known to be infested by azalea lace bug.
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 the underside of the leaf surface, especially along leaf veins where the female inserts her eggs.
- Eggs are white, smooth, and flask-shaped with a neck to one side.
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 proper levels of insecticides 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.
- Xytect™ and Transtect™ will provide a high level of control against lace bugs.
- Insecticides will not restore a damaged appearance, but can reduce or prevent further damage.
- Lace bug 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.
- Avoid using nitrogen fertilizers until the lace bug pests are controlled.
A Diagnostic Guide is designed to help you identify a pest issue and management solutions. Always refer to product label for all rates and approved uses. Some images courtesy forestryimages.org. Use of the images does not imply endorsement of treatments by forestryimages.org