Darrell Blackwelder: Controlling azalea lace bugs

Published 12:00 am Saturday, June 24, 2023

I was walking by some newly planted azaleas at St. John’s Lutheran Church in Salisbury and noticed the leaves of some newly planted azaleas were pale with yellow splotches. It’s a common problem caused by an insect — the azalea lace bug. This very small, clear-winged insect a problem during the summer growing season. The foliage is inundated with small, dotted, yellow splotches at first, and then turns completely yellow after a massive infestation. Premature leaf drop often occurs when plants are heavily infested.

These minute insects are found on the underside of leaves along with tiny black splotches of excrement resembling dark varnish. Eggs overwinter under these dark splotches hatching into adults later in the spring and early summer.

Adult lace bugs have clear lace-like wings with an expanded, lacy hood on the back of the head. Adults are very small, about 1/8-inch-long and 1/16 inch wide. This insect spends the winter in the egg stage under black excrement on the undersides of the leaves.

Repeated applications of insecticides labeled for azaleas or insecticidal soap effectively control lace bugs. Make the first application as soon as nymphs appear on the undersides of the leaves. Follow with a second application 7 to 10 days repeating as needed.

Thorough coverage is essential when applying sprays if good control is expected. It is very important the underside of the leaves is covered. Use high pressure to make sure the underneath of the leaves is covered. Simply spraying over the top of the plant will not control the pest. Systemic insecticides containing the active ingredient, imidacloprid can also be applied as a soil drench which controls the pest without constant spraying. Go to https://content.ces.ncsu.edu/azalea-lace-bug for more detailed information for lace bug control.

Darrell Blackwelder is the retired horticulture agent and director with the North Carolina Cooperative Extension Service in Rowan County. Contact him at deblackw@ncsu.edu.


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