Bees and wasps aren't interested in eating the scale themselves (of the two groups, only wasps would prey on other insects). Instead, they are visiting due to the scale's honeydew, which is a sugar-water type of waste liquid they produce, along with other sap-sucking insects like aphids and spotted lanternfly. Crapemyrtles do host an aphid species that feeds only on their foliage, so it's always possible a tree has both pests present at once. (Of the two, Crapemyrtle Bark Scale is more consequential.)

Physical removal of scale you can reach is the most low-impact approach, though treatment with pesticides (even if largely organic ingredients) is usually needed to get good population control for this scale. The management section of our Introduction to Scale Insects page presents the various options for treating any scale outbreak. Lower-risk options like horticultural oil can be used (multiple treatments will be needed) if you prefer to avoid systemic ingredients. For most of the latter choices, you would need to hire a certified pesticide applicator due to regulations in Maryland for those pesticides. (Plus, for any tree large enough, any spray, even an organic one, should be applied by a professional so they get good coverage for best efficacy.)

There is no scale-specific pesticide, but a middle-ground to oil versus systemics would be an insect growth regulator (IGR). Applied by a professional with experience in treating scale (so they know what life stage to look for), its use can be targeted to juvenile scale stages, since the chemical prevents the insects from maturing so they cannot breed or continue feeding. Well-timed exposure to any pesticide selected will minimize harm to other organisms, like pollinators and any predatory insects consuming the scale directly. (There are some ladybug larvae that look very scale-like that eat them, though they will not eradicate a large population by themselves.) Professionals with IPM (integrated pest management) training know to look for beneficial insects and can assess a situation to determine the best approach to take when suppressing pests; usually it's a multi-pronged approach to reduce any tree stress that might be making it more vulnerable to attack combined with lower-risk pesticide applications. Worst-case, if a systemic insecticide is the most effective treatment for the time being to knock scale numbers down more quickly, the tree can be disbudded (flower buds / open flowers removed) in order to avoid pollinator exposure during that year of treatment.

Do not prune scale-infested growth off unless you are willing to let the plant regrow for several years to regain its former size. Pruning out scale-laden branches or trunks is more practical for dwarf, shrubby varieties of Crapemyrtle, not tree-sized specimens, given the amount of stress this could cause the plant and the number of cuts it would then need to seal-over. In either case, never top the tree; it's a harmful pruning practice that creates problems with branch sturdiness, interferes with blooming, and weakens trees overall. (Refer to page 23 of the Forest Service's Tree Owners Manual.) It is a practice still used by some landscapers or residents, presumably for aesthetics, but it is a result of poor training or unfamiliarity with tree biology. Certified arborists don't condone the practice.

For routine pruning to remove crossing branches or make minor adjustments to tree shape or size, this can be done in spring as new growth begins to emerge. (Crapemyrtles leaf-out comparatively late, so this might be April or even early May sometime.) Dead wood and broken branches can be pruned off at any time of year.

Miri