The azalea lacebug is a pest that gardeners in the South face nearly every year. As azaleas begin to bloom, this insect begins its lifecycle. By the end of the summer, gardeners may find their azalea plants stressed and the leaves covered with yellow speckles. This leads to reduced plant vigor and flowering the following year.
Although azalea lace bugs attack azaleas and rhododendrons primarily, they may infest other ornamentals as well. They damage plants by feeding on sap from leaves through sucking mouth parts. Lace bugs often go undetected on the undersides of leaves until their numbers are high. Prolonged attacks can severely weaken azaleas and may be the primary cause of death.
Less serious infestations often go unnoticed whereas heavy infestations will cause the foliage to turn brown. Damage first appears as speckling or yellow spotting caused by the insect’s feeding on leaves with its sucking mouthparts. Feeding mars the appearance of foliage on both deciduous and evergreen azaleas.
The feeding occurs on the undersides of the leaves and then becomes apparent on the upper leaf surface in the form of bleached, chlorotic spots that persist through leaf drop. Brown and black excrement and old skins are often seen under the leaves
The adults are between 3 mm long and 1.5 mm wide and dark in color. The insects have a hood-like covering on the head and net-like, lacy, off-white wings with mottled brownish-black markings that may be seen with a hand lens. The insect resembles a fly that has lacy wings, thus the name lacebug.
Eggs may be visible with the use of a hand lens and appear as smooth, white football-shaped objects that are deposited on the underside of leaves. These deposits are usually found along the central leaf vein and are covered with blackish, varnish-like fecal spots that are a diagnostic sign.
Nymphs, the tiny immature insects that follow the eggs in the lacebug lifecycle, are colorless when newly hatched, but quickly become dark and develop spines. The insect passes through five nymphal stages and sheds its skin each time. The cast skins often remain attached to the underside of leaves.
Azalea lacebugs over-winter primarily as eggs on the underside of leaves, thus favoring evergreen azaleas. Eggs mature in response to temperature and in Georgia typically begin to hatch in March to early April. There are usually 3 to 4 generations per year and during the growing season the insect progresses from egg to adult in about 30 days.
Controlling this insect is simple. If only a few lace bugs are present, they may be washed off with a strong stream of water. Horticultural oils and soaps also control lace bugs. Natural predators such as Mirid plant bugs and the mymarid wasp help control the azalea lace bug.
Should heavier infestations be found, pesticide treatments may be necessary. Chemical controls include imidacloprid, malahtion and sevin. Azaleas growing in full sun appear to have heavier infestations. Remember to read the label carefully and follow all instructions when using pesticides.
Randy Drinkard is the ANR Agent for The University of Georgia Troup/Meriwether County Cooperative Extension. The Troup County Extension office is located at 114 Church St. and can be reached at 706-883-1675. Open Monday through Friday, 8 a.m. to 5 p.m.