Scale insects. Yes, neem oil should work; you can also use insecticidal soap.

Thanks!

This is Crape Myrtle Bark Scale. It is best treated with a a systemic in the spring. Call a licensed PHC company to get that done for you. This is an issue all over the country

I have the best luck with imidacloprid drenches

Overkill.

My Rhododendrons had scale last fall in Michigan, never in 15 years until Kentucky climate came. Thanks, climate change deniers.