Northwest berry Foundation

Management Detail

Azalea Bark Scale

in Blueberries

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Latin name: Eriococcus azaleas


Reason for Concern
1) Only recently identified in Oregon blueberries.
2) Pest infestations may spread from the canes to the fruit.
3) Ovisacs and various other developmental stages on the fruit may result in the fruit being unmarketable or lower in value.
4) Heavy infestations may lead to premature leaf drop due to inefficient photosynthesis and may weaker growth, resulting in a smaller crop next season.
5) Older plantings are more susceptible due to readily available and suitable feeding and refuge sites.

The adult female is dark red with short legs and antennae and long, sucking mouthparts. It is hidden from view by the egg sac (ovisac), a covering of felted/matted waxy threads. It can be found on bark and stems and has a woolly or cottony appearance. The sac is about 3 mm long and 1.5 mm thick. Mature females tend to feed in crotches and on twigs. Adult males, 2-winged and tiny, tend to feed on the leaves.

Overwinter as nymphs feeding on the bark. As the female reaches maturity, she secretes white, waxy threads, which become matted creating a thick shell covering her body. After mating, she lays red eggs within this egg sac in the spring, then her body shrinks until the sac is almost completely filled with eggs. In about 3 weeks, tiny nymphs hatch from the eggs (late spring/early summer) and the young crawlers disperse, settling in bark crevices, branch crotches, and sometimes on new growth and leaves Nymphs (crawlers) penetrate the bark with long, sucking mouthparts and feed. They mature during the summer and over winter in the adult form.



  • Make a thorough search of the old wood areas looking for egg sacs, ants and sooty mold.
  • Scrape the egg sac to expose the red eggs.
  • Tag the cane for potential pruning.
  • Double-sided sticky tape can be put around canes during the late dormant period in fields where active pest populations are suspected. These can be put in close proximity to the eggs sacs in a grid pattern throughout the field. Tape can be removed during the start of bud break and when temperatures start to increase.
  • Change the tape every second week and use a microscope to detect activity level.

Cultural Controls:

None listed at present.


For information about chemical controls, check with our Pesticide Guide.


Photo by R. Rosetta

Exposed red eggs - Photo by R. Rosetta

Photo by R. Rosetta


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