Looks like euonymus scale, tough to get rid of.
hortster

Agreed. Very common on euonymus. Choose the remedy that comports with your worldview.

Dan

Just so you know....'scale' is a dreaded INSECT pest. And your shrub is a euonymus of one kind or another. If you have euonymus, you'll probably end up with a scale infestation.

In the event that you are really interested, the white flakes are the adult male of the species and the differently shaped darker ones are the adult females.

I think that I'd rate this as a pretty serious infestation.

Probably scale and the most often used control is a horticultural oil which smothers the wee buggers. During the growing season a "summer" oil can be used, with care. During the dormant season a "dormant oil" can be used.

Here is a link that might be useful: scale on plants

Thank you everyone for the replies! I'll look into management of scale and treatment alternatives.

Just remember that many of us have removed euonymus entirely because of this problem. A heavy infestation such as yours is very difficult to get under control. It's likely that you'll have to deal with scale on this shrub for the rest of its natural life, even if you are able to get the problem under management.

One method (other than total removal) might entail cutting the whole plant back to the ground this coming spring, then applying horticultural oil at different times during the year. The new growth will emerge scale-less, but you'll have to keep after it to maintain it.