What Are Those Bugs On My Crape Myrtle?

United States since then. Although it recently arrived in Norfolk, Steven Traylor, the City Arborist, recently noted that CMBS is extensively present throughout Norfolk. Although Norfolk City budgetary constraints prevent the city from having a plant health care (PHC) program to do remediating treatments, the Bureau of Parks and Urban Forestry does issue permits for PHC treatment work to be done at private cost of citizens if they are interested.  A good discussion of CMBS and treatment options can be found in the Clemson Cooperative Information Center factsheet is located at https://hgic.clemson.edu/factsheet/crapemyrtle-bark-scale/.

Chris Epes is the City of Norfolk’s Associate Virginia Cooperative Extension (VCE) Agent for Agriculture and Natural Resources. When talking to me about CMBS, Chris made the following points:

CMBS tends to extensively infest those crape myrtles that are already under stress. The reason you frequently see them in high numbers on verge trees is because they have little pervious space around the roots and are subjected to higher than normal heat from the surrounding pavement. You may also see them in large quantities on trees that get topped or “crape-murdered” annually, trees that are planted in too much shade, or trees that simply don’t get enough water wherever they may be located. So, for this reason, Chris always suggests to first attempt to use “cultural” controls to improve the health of the tree.  Doing this successfully should result in a crape myrtle that tolerates a small infestation, as most of the healthy trees in Norfolk do.

Cultural controls include making sure that your tree is planted in a full-sun location, making sure the soil is moist, well-draining, not overly compacted and contains a reasonable amount of organic matter. It also means making sure the tree is getting watered periodically through the hot, dry parts of the summer. It means to prune the tree only to remove the dead branches and branches that are crossing and touching and never under any circumstance top or “crape-murder” the tree. De-suckering would be an acceptable pruning measure for a crape myrtle, as sucker growth, especially profuse sucker growth, is fundamentally a stress response. It means that for some reason the tree is under duress. Might that be because of CMBS? Sure, but it could also because of other environmental factors. Identifying and fixing the problem/problems will be helpful in both reducing future suckering and future pest infestation.

VCE discourages use of chemical applications for this problem, although it is legal to do so in Virginia. The only effective chemical control involves using a concentrated neonicotinoid pesticide that must be mixed with water per the label instructions and poured over the root zone around the base of the tree. The tree will then absorb the insecticide via the roots and translocate it throughout the canopy. Given the lag between application and complete translocation, there may be a few weeks to a month before you begin to see much control, and that would be based on weather/rainfall which would dictate the degree to which the tree is translocating fluids. In addition, much of Norfolk is so close to the water table that the likelihood of contaminating the groundwater is high. Similarly, although there does not appear to be a consensus among researchers, neonicotinoid pesticides inside the flower parts and pollen may be harmful to pollinators that graze the flowers. Accordingly, most researchers tend to err on the side of caution and recommend that use of these chemicals be limited.

Chris also stressed, “If cultural controls are not effective, I recommend simply replacing the tree with something more suited to the space, otherwise you’ll be locked into either a perpetual infestation and the ultimate demise of the tree, or having to do chemical applications annually. This is going to be far more expensive, far more potentially dangerous to the applicator and far more potentially dangerous to the environment in the long run than simply replacing the tree with something that is ultimately healthy, happy and unfettered in the space.”

Finally, if you do decide to go the chemical treatment route, have an expert treat the tree for you. Don’t try to “do it on your own”, as misuse of the chemical treatment products can have a detrimental effect on you, your pets, and the environment. Do not forget to get a permit from the Bureau of Parks and Urban Forestry before spraying any city trees. A permit application can be downloaded from https://www.norfolk.gov/DocumentCenter/View/917/Tree-Street-Application?bidId=  and can be submitted via email to the address treepermits@norfolk.gov. Check the box for “Spray/treat” and indicate “crape myrtle bark scale” as the purpose for which the permit is requested.

Fun fact: The common name for Lagerstroemia indica can be spelled either crepe myrtle or crape myrtle. Crape myrtle is the oldest known spelling and is generally preferred by botanists. The traditional Southern spelling is crepe myrtle. However, across the rest of the US it is more commonly spelled crape myrtle. Choose your poison, technically either is correct.