Looks to be lecanium scale. No sense treating until the crawlers (babies)
emerge from the "shells," then use an ultrafine horticultural oil spray. I
don't know where you live, but if you're familiar with growing degree days,
they usually emerge somewhere between 700-800 GDD. Here in Wisconsin,
that's usually sometime in July.
Suzy, Zone 5, Wisconsin
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.