Why Are Crepe Myrtles Turning Black?

It is a rare neighborhood in North Texas that does not have a crepe myrtle or two planted along its streets. Crepe myrtles bloom in the summer, adding color and pop to any landscape. But like any plant in your yard, crepe myrtles need the right care and treatment, or they could become diseased or infested.

Crepe Myrtle. Photo: Scott Geer.

Crepe Myrtle Bark Scale

In North Texas, crepe myrtles contend with an insect known as crepe myrtle bark scale. Crepe myrtle bark scale is a relatively new insect to the area. They were first detected in North Texas in 2004.

Originally from China, crepe myrtle bark scale initially did not have a sizable number of predators to reduce a population surge in the spring. This led to incidents of outbreaks, causing crepe myrtles to turn black from the mold that develops from a “honeydew” residue that the insect leaves behind. The activity of the insect also reduces the energy levels of tree and thus reduces the number of blooms and restricts growth.

Twice-stabbed ladybugs are one known predator of crepe myrtle bark scale. A sufficient population of twice-stabbed ladybugs (Chilocorus stigma) can devastate a crepe myrtle bark scale population on a tree within a week.

Twice stabbed ladybug on a leaf
Twice-stabbed ladybug. Photo: Katja Schulz C.C. by 2.0.

While topical insecticides cannot be used alongside ladybugs, an alternative method is the use of a systemic insecticide. This approach is recommended if the crepe myrtle bark scale numbers are high.

What You Can Do for Your Crepe Myrtles

Managing an infestation of crepe myrtle bark scale will eliminate the production of black sooty mold on the bark of the tree. The blackened bark will usually slough off within a year. However, if it is desired to rid the tree of the unsightly blackened bark sooner, the black sooty mold can be removed with a mild, dish soap and water with a scrub brush.

Krista White

Krista White

Krista is a member of the marketing and education team at Tree Shepherds. A lifelong learner, she loves writing about anything from Hemingway to Quercus macrocarpa.