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Yale Park Homeowners Association

Texas AgriLife Extension Service

Kimberly Schofield
Program Specialist-Urban IPM

Are Azalea Bark Scales Attacking Your Crape Myrtles?

The azalea bark scale, Eriococcus azaleae Comstock, is not a new pest since it was discovered on outdoor azalea plantings throughout the South in 1881.  However, it was found in Dallas attacking crape myrtles three years ago.  This seems to be a new host plant for the azalea bark scale and the population seems to be expanding year after year into new areas.

These scales appear white in color, since they will be covered with waxy secretions.  They can be found anywhere on the plant, but tend to be found mainly in the branch crotches and pruning wounds.  The females can lay around 50-250 reddish eggs and they will protect them under their bodies.  Once the eggs hatch, the nymphs (crawlers) are light yellow in color and will crawl to a new location to begin feeding.  This scale usually has two generations per year and overwinters in the egg or nymphal stage.

One of the first signs of infestation to look for is the presence of sooty mold that will appear on the trunk and branches of crape myrtles.  You will also notice the presence of honeydew on limbs and leaves.

Unfortunately these scales are hard to control and control recommendations for Texas are still being developed.  One suggestion is to mix dishwashing soap with water and wash the trunk and branches with a brush. This will remove many of the female scales and eggs.  It will also remove some of the sooty mold.  Systemic insecticides such as something containing imidacloprid or acephate can also be used to control these scales.  In addition, insecticidal sprays containing such chemicals as malathion or bifenthrin will provide control when the scale is in the crawler stage.  It is believed that March to mid-April will be the best time to spray.  Also in the winter, dormant oil applications to the bark and crotches will provide control.  Remember that the plant must be thoroughly covered when treating with oil.

Please visit http://citybugs.tamu.edu for more information.

Photo of azalea bark scale, Eriococcus azaleae Comstock, on crape myrtle.
Photo of azalea bark scale, Eriococcus azaleae Comstock, on crape myrtle.
Photo by: Michael Merchant, Professor and Extension Entomologist,
Texas A&M University.

Mention of commercial products is for educational purposes only and does not represent endorsement by Texas AgriLife Extension or The Texas A&M University System.  Insecticide label registrations are subject to change, and changes may have occurred since this publication was printed.  The pesticide user is always responsible for applying products in accordance with label directions.  Always read and carefully follow the instructions on the container label.

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