Tiny pests, big problems: spots, specks and lace bugs

Many azaleas have recently bloomed or are about to begin blooming and that means lace bugs will start hatching and sucking the sap from our lovely southern shrubs. Lace bugs are important pests of many ornamental trees and shrubs. They attack a broad range of evergreen and deciduous trees and shrubs and often go undetected until the infested plants show severe damage. 

If you’ve noticed a speckling on your azalea leaves and a general yellowing, take a look at the undersides of the leaves and you are likely to see brown to black droplets of excrement and old “skins” of the nymphs on the underside of damaged leaves. That means you had lace bugs last year.  And you’ll most likely have them again this year as the adults laid eggs that will soon hatch.

Both adults and nymphs have needle-like mouthparts that suck sap as they feed from the underside of the leaf. The damage to the leaves makes the azalea look ugly, reduces the plants’ ability to produce food, decreases plant vigor and causes the plant to be more susceptible to damage by other insects, diseases or unfavorable weather conditions. Repeated, heavy infestations of lace bugs can kill the plant.

The eggs begin hatching around this time and the nymphs begin sucking sap on the undersides of the leaves. The nymphs go through several molts and then you’ll see the rectangular adults which also feed the same way. They get their name because the wings are lacy looking, but they are very tiny (1/4 inch) and hard to see. There will be four generations a year, so they feed on our poor azaleas all summer.

It is important to prevent the damage early. The foliage won’t clear up — you’ll have these unsightly, speckled, yellowish leaves, instead of nice green azalea leaves —  if you allow the insects to start feeding before you kill them. 

Lace bug damage on evergreens is most common and severe on azalea, pyracantha, rhododendron and andromeda. 

Lace bugs also attack a wide range of deciduous trees and shrubs. Plants found in the Georgia landscape that are commonly infested include lantana, hawthorn, cotoneaster, quince, American elm, apple, sycamore, oak and cherry. Recently, significant lace bug damage was observed on ornamental grasses, which are common in southern U.S. landscapes.

Control involves inspecting your azaleas in early spring for the presence of newly hatched nymphs. Inspect these plants every two weeks during the growing season for developing lace bug infestations. Where plants have a history of lace bug infestation, control measures should be applied in late March, or when you first see nymphs.  

If you only see a few lace bugs and little to no damage is observed, wash lace bugs off infested plants with a strong stream of water from a garden hose.  Repeated applications of insecticidal soaps or horticultural oils are also effective in controlling lace bug populations. Make sure you aim towards the undersides of the leaves where the insect is often found.

Prior to initiating a chemical control program, look for lace bug predators like the mirid plant bugs, a small narrow bright red and black insect.  

In dealing with heavy infestations, chemical control is often necessary. Treatment of infested plants in early spring during the development of the first generation of lace bugs may reduce the number of insecticide applications needed to control heavy populations. Your county extension office can help you with recommendations. 

Take a look at the undersides of your azalea leaves this weekend and hopefully you won’t see the azalea lace bug, but if you do, you’ve caught it early and have a good chance of controlling this bad boy and keeping your azaleas happy and healthy this summer!

For more information, read this University of Georgia resource. Jule-Lynne Macie is the acting County Extension Coordinator for Macon-Bibb County Extension and is the Northwest District ANR Program Development Coordinator. If you have any questions for us, please call Bibb County Cooperative Extension at 478-310-5350 or email us at bibb.extension@uga.edu