Azalea Lace Bug

Description: The azalea lace bug, is the most frequently reported insect pest in the landscape. They are called “lace” bugs because the wings resemble lace. The wings are mostly transparent with some dark markings and are about 1/8 inch long. Lace bugs spend the winter in the egg stage inside a leaf covered with a drop of excrement that hardens into a varnish-like shield. Eggs are usually deposited in a young leaf along the midrib or a large vein and is inserted with its neck slightly above the leaf surface. Up to 90 eggs have been found in a single leaf. Newly hatched lace bugs (nymphs) are almost colorless at hatching but are soon dark and spiny and they molt six times before reaching the adult stage. Azalea lace bugs, eggs, and nymphs are found on the undersides of leaves.

Targets: Evergreen azaleas are the most likely to be infested but deciduous cultivars and mountain laurel can be attacked. Lace bugs feed by inserting their needle-like mouthparts into leaves and injecting saliva. When the lace bug sucks out the predigested cell contents, the empty cell walls form a noticeable pale spot. After a short time, lace bugs cause the leaves to become bleached out and bronzed.

Control: Azalea lace bugs can be relatively difficult to control. Perhaps this is because the eggs are inserted into the leaf tissue and covered with a drop of varnish-like excrement and are thereby protected from insecticides. Azalea lace bug eggs are plagued by tiny parasitic wasps and predaceous azalea plant bugs. However, these natural control agents often fail to prevent noticeable damage.

If predators are not limiting damage, the next step is to consider chemical treatment.  The best time to treat is early spring which may keep later populations low and because the spring generations seem to do the most damage. There are several potential approaches to control:

  • Orthene is relatively effective for lace bug control, but also impacts predators and parasites.
  • Insecticidal soaps and horticultural oils are toxic to lace bug nymphs and adults, but they do not kill eggs nor do they provide any residual control but are safer for parasites and predators.
  • Safari and imidacloprid are systemic insecticides that are applied to the soil surface to kill the lace bugs.
  • Acelepryn and Flagship soak into the leaf, but do not move systemically in the plant.

As always, follow all package instructions and consider the impact on other insects, like bees, butterflies and moths that you want to protect.

Credit: North Carolina Cooperative Extension