Soft scale on arrowwood (Viburnum dentatum) - Ceroplastes cirripediformis
Briar Bush Nature Center, Montgomery County, Pennsylvania, USA January 20, 2013 Size: 5 mm
It looks like Ceroplastes cirripediformis, which has not been reported from PA yet.
There were two. The other one measured 4 mm.
Would it be adult or immature?