Management of established or high scale populations can be challenging and may take a full year or more to be successful. Horticultural oil, applied as a dormant oil rate (as per label directions), can help to smother scale currently residing on the bark, but may not kill them all, so follow-up treatments of "summer rate" hort. oil (or other insecticide options) may be needed during the growing season. There are a minimum of two generations per year in our area with this scale species, so control efforts may need to focus on the crawler period of each generation. The timing of this is still being researched to fine-tune date ranges regarding when to expect crawler emergence for Crapemyrtle Bark Scale, since it's a relatively new pest to the mid-Atlantic. A couple of the alternative pesticide options (systemic applications) may need to be applied by a certified pesticide applicator (who can also help monitor for crawlers, since they're very tiny), though this approach will need to take into consideration the plant's flowering period since such chemicals may risk entering the pollen/nectar as well. Hort. oil treatments, having relatively low toxicity, is a good place to start to see how much suppression that alone will achieve.

Miri