The following is information on white prunicola scale. This scale pest has active crawlers this time of year.
White prunicola scale crawlers are active. This armored scale feeds on a number of hosts including: Acer, Alunus, Aucuba, Buxus, Forsythia, Ilex, Ligustrum, Malus, Prunus, Rhododendron, Syringa, and others. Crawlers of the second generation are active at 2314 - 3586 [3010 peak] GDD. Male scales are elongate, felted, white and light yellow at one end; whereas females are round with light yellow covers slightly off center. Male scales are inconspicuous white masses on the undersides of branches. Chemical control includes horticultural oil, insecticidal soap, dinotefuran (Safari), pyriproxyfen (Distance) or one of the pyrethroids.
White prunicola scale. Photo from the June 3, 2005 edition of the Branching Out newsletter from Cornell Cooperative Extension
Information from Brian Kunkel, Ornamental IPM Specialist, UD