Crape Myrtle Bark Scale (CMBS)
CMBS
Crape Myrtle Bark Scale is an insect scientifically known as Eriococcus lagerstroemiae. Female adults are relatively easy to see, appearing as fluffy white and gray, at about 2mm long. These soft scale insects infest crape myrtle trees. CMBS is problematic in our region for several reasons.
Invasive Species
This insect is an exotic species in North America, having been introduced sometime prior to first being observed in Texas in 2004. This pest is proving to be invasive as it spreads across North America causing severe infestations. While a number of natural predators to this species of pest have been identified to be potentially able to control its population, there is often a lag between an invasion of an exotic pest and natural predators gaining control of its population.
Sap-sucking Insects
The larva of this insect sucks the sap out of its host tree. Sap contains essential nutrients like water, sugars, and minerals. While it is rare for a sap-sucking insect infestation to kill a crape myrtle, this feeding will weaken a tree.
Honeydew and Sooty Mold
One of the telltale signs of a CMBS infestation is the presence of honeydew, a sticky substance excreted by the scale insects. Honeydew itself is not directly harmful to the tree, but it creates an environment that encourages the growth of sooty mold. Sooty mold is a dark fungus that grows on the honeydew, covering the leaves and stems of the crape myrtle, as well as other plants and surfaces below. When leaves are coated with sooty mold, photosynthesis is inhibited and the tree (or other plant) is weakened over time.
Temperature-Dependent
CBMS has a rapid reproduction cycle. The scale can complete two to four generations per year, with warmer temperatures accelerating the process. This means that in warmer climates or during periods of global warming, the scale can produce more generations at a quicker rate, leading to more extensive infestations.
Further Reading
For more information, here are some good resources:
Crape Myrtle Bark Scale: This resource from the University of Maryland Extension provides additional information on CMBS, including its identification, life cycle, and management strategies. (https://extension.umd.edu/resource/crapemyrtle-bark-scale/)
Temperature-Dependent Development and Host Range of Crapemyrtle Bark Scale: This journal article discusses the relationship between temperature and the development of CMBS, as well as the scale's host range. (https://bioone.org/journals/florida-entomologist/volume-102/issue-1/024.102.0129/Temperature-Dependent-Development-and-Host-Range-of-Crapemyrtle-Bark-Scale/10.1653/024.102.0129.full)
