Azalea bark scale

The azalea bark scale, Eriococcus azaleae Comstock, can be found on a variety of hosts grown in nurseries and landscapes including azalea, rhododendron, andromeda, hawthorn, poplar, willow, and most recently, it has been found infesting blueberries in the Pacific northwest. It can be found on bark and stems and has a woolly or cottony appearance.

It is reported to have one generation a year in Connecticut but may have two generations in warmer climates such as the south. The overwintering females lay eggs under the scale in the spring. The eggs hatch in the late spring/early summer and the young crawlers disperse and soon settle, mostly in bark crevices, branch crotches, and but also onto new growth and leaves. In 2006 crawlers were captured on double-sided sticky tape place on June 9 and read on June 12.

Original version: <6 July 2006)

Last revision <2 December 2016>

Author: R.L. Rosetta, Extension Nursery Integrated Pest Management, Department of Horticulture, Oregon State University/NWREC.

Azalea bark scale on blueberry

Azalea bark scale on blueberry

Azalea bark scale on blueberry closeup

Azalea bark scale and black sooty mold on rhododendron

Azalea bark scale in leaf axil

Azalea bark scale in leaf axil

Exposed eggs under scale shell

Exposed eggs under scale shell

Closeup of scale eggs

Closeup of scale eggs

Double-sided sticky tape with crawlers (note large numbers of crawlers near arrows)

Double-sided sticky tape with crawlers

Close-up of crawlers

Close-up of crawler stuck in tape