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This crape myrtle branch is encrusted in the white felt of crape myrtle bark scale, an invasive insect that damages the once low-maintenance trees. (Photo by MSU Extension/Blake Layton)

Invasive crape myrtle pest spreading in state

MSU Extension Service

STARKVILLE, Miss. -- Mississippi State University experts found an invasive insect that attacks crape myrtles on the coast this spring and now have spotted the pest in two cities on opposite ends of the state.

The insects are crape myrtle bark scale, or CMBS, and they were found March 15 in Ocean Springs in Jackson County. In August, the insects were detected at five locations in Olive Branch and Southaven in DeSoto County.

The pest appears to be well established in these cities and has been detected in both home and commercial landscapes in each area. More recently, a potential CMBS infestation has been reported in northeast Mississippi.

Blake Layton, an entomologist with the Mississippi State University Extension Service, said infected crape myrtles become black and ugly with accumulations of sooty mold. The pest leads to poor growth and poor bloom production.

“CMBS has the potential to turn what has traditionally been a beautiful, low-maintenance landscape tree into an ugly, high-maintenance tree,” Layton said. “With established populations at both ends of the state, this serious, non-native pest could easily spread to other areas.”

Angie Rogers is the Extension agriculture and natural resources agent in Jackson County, where the pest was first found in the state.

“We did an outing in the county and visited with the two businesses and one homeowner who had the scale insect in the crape myrtles in their landscape,” Rogers said. “We also found it in a few of the crape myrtles in the median along Highway 90 in Ocean Springs.”

Joy Anderson, agriculture and natural resources Extension agent and DeSoto County coordinator, said the pest has been identified in the landscape at one commercial location and four houses in her area.

“Plant stress contributes to the problem, but the question is how are they getting there, because some of the sites are pretty far apart,” Anderson said.

In addition to invasive CMBS, DeSoto County is also in the path of the emerald ash borer, another invasive, introduced pest, Anderson said.

“When we started finding crape myrtle bark scale, we began to plan some training for both it and the emerald ash borer, which has been detected in Tennessee,” she said. “These insects can have a big economic impact on our area if they become established, so we want to teach people how to identify the pest and what to do if they have it on their property.”

Layton said heavy infestations of CMBS are easy to identify.

“Look for crape myrtles with heavy accumulations of black, sooty mold, but remember that heavy aphid infestations can also cause this symptom,” Layton said. “Then, look more closely for patches of white, felt-like material on the trunk, limbs or twigs.”

He said individual adult female scale are oval-shaped and about one-tenth of an inch long. Heavily infested limbs may have so many scale that they are totally encrusted with the insects. A definitive characteristic of the scale is that it bleeds pink when its felt cover is broken with a knifepoint or toothpick.

Layton said the best offense is a good defense against crape myrtle bark scale.

“Avoid buying and planting infested crape myrtles,” he said. “Work closely with your nursery to be sure any crape myrtles you purchase are CMBS-free, because low-level infestations are difficult to detect.”

If CMBS are suspected, notify the local county Extension office immediately and begin an aggressive control program.

“The goal is to eliminate CMBS and CMBS-infected plants from the landscape before the infestation can spread,” Layton said. “Control options for infested trees include soil-applied systemic insecticides containing dinotefuran or imidacloprid, and foliar insecticide sprays containing insecticides or insect growth regulators that control immature stages of CMBS.”

Visit the local county Extension office to report suspected infestations of crape myrtle bark scale or to get information on how to recognize and control this pest. Ask for a copy of Layton’s “Crape Myrtle Bark Scale Scouting and Control Recommendations.”

Released: September 9, 2015
Photos for publication (click for high resolution image):
  • This crape myrtle branch is encrusted in the white felt of crape myrtle bark scale, an invasive insect that damages the once low-maintenance trees. (Photo by MSU Extension/Blake Layton)
  • This heavy accumulation of black, sooty mold and patches of white, felt-like material are evidence that this crape myrtle has a heavy infestation of the invasive crape myrtle bark scale. (Photo by MSU Extension/Angie Rogers)
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