Best way to treat Crepe Myrtle Bark Scale - Ask Extension
I am located in Hanover, MD and I have three Crepe Myrtle trees in my backyard that I planted about three years ago. During this past summer, they had...
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Best way to treat Crepe Myrtle Bark Scale #923744
Asked January 18, 2026, 12:47 PM EST
I am located in Hanover, MD and I have three Crepe Myrtle trees in my backyard that I planted about three years ago. During this past summer, they had a significant amount of 'Crepe Myrtle Bark Scale' for the first time. There where many white bumps, it was pinkish when scraped off, and it left a black soot like residue on the branches and leaves. I scrubbed them down on two occasions; while this helped, the scale eventually returned.
What is your recommendation for treating this invasive pest and protecting my trees?
Thank you,
John
Anne Arundel County Maryland
Expert Response
Manual removal by periodically scrubbing them off can sufficiently reduce the population, but if you need to escalate the management to using insecticides, it may be best to hire a professional (certified pesticide applicator). Not only do professional applicators tend to have better-quality, calibrated spray or injection equipment for making more thorough and effective applications, but in some cases, the insecticide ingredient used may have legal restrictions that do not allow uncertified persons to purchase and apply it. (For example, systemic pesticides in the neonicotinoid chemical class are under such legal restrictions in Maryland, as they can harm pollinators visiting the blooms of a treated plant.) Lower-risk pesticide options for Crapemyrtle Bark Scale include topical sprays of horticultural oil and/or IGRs (insect growth regulators) that interfere with the maturation/development of the insects so they don't keep feeding and breeding.
Fortunately, we're finding that enough natural predators consume this scale and can keep populations in check on their own. Using some insecticide sprays (including for other purposes, like an aerial yard mosquito treatment) can negatively affect these beneficial insects and allow scale numbers to rise as a result. Plants growing in stressful conditions, like drought or near pavement reflecting extra heat in summer, can also be more vulnerable to pest outbreaks. While heavy populations that persist for several seasons may kill some Crapemyrtle branches, overall, they are more of a nuisance (especially given the secondary sooty mold growth) than a threat to the plant's health. With a minimum of two generations per year, any topical spray that targets scale crawlers (the most vulnerable life stage) may need to be applied at least twice a year. Professional pesticide applicators with experience treating scale should be accustomed to monitoring scale insects to determine when crawlers are present, in order to set the timing of any pesticide use for maximum efficacy.
Even if the scale are successfully eradicated, they could potentially recolonize the trees at any time. Scale crawlers are tiny, but even though they don't move far under their own power, they can easily "hitch a ride" on other animals (bird feet, for instance) or blow about the landscape on the wind. In a healthy landscape that has other resources to support beneficial insects like those scale predators and parasites, a recolonization by the scale won't necessarily result in another noticeable outbreak.
If you decide to have the trees treated with a systemic insecticide, be aware that this may make the plant's blooms (even weeks or months after an application) hazardous for pollinators to visit. Some chemicals have longer residual activity than others, so a professional applicator can also help choose pesticides that won't last as long after application to minimize the risk to pollinators and scale predators.
Miri
Fortunately, we're finding that enough natural predators consume this scale and can keep populations in check on their own. Using some insecticide sprays (including for other purposes, like an aerial yard mosquito treatment) can negatively affect these beneficial insects and allow scale numbers to rise as a result. Plants growing in stressful conditions, like drought or near pavement reflecting extra heat in summer, can also be more vulnerable to pest outbreaks. While heavy populations that persist for several seasons may kill some Crapemyrtle branches, overall, they are more of a nuisance (especially given the secondary sooty mold growth) than a threat to the plant's health. With a minimum of two generations per year, any topical spray that targets scale crawlers (the most vulnerable life stage) may need to be applied at least twice a year. Professional pesticide applicators with experience treating scale should be accustomed to monitoring scale insects to determine when crawlers are present, in order to set the timing of any pesticide use for maximum efficacy.
Even if the scale are successfully eradicated, they could potentially recolonize the trees at any time. Scale crawlers are tiny, but even though they don't move far under their own power, they can easily "hitch a ride" on other animals (bird feet, for instance) or blow about the landscape on the wind. In a healthy landscape that has other resources to support beneficial insects like those scale predators and parasites, a recolonization by the scale won't necessarily result in another noticeable outbreak.
If you decide to have the trees treated with a systemic insecticide, be aware that this may make the plant's blooms (even weeks or months after an application) hazardous for pollinators to visit. Some chemicals have longer residual activity than others, so a professional applicator can also help choose pesticides that won't last as long after application to minimize the risk to pollinators and scale predators.
Miri
