WSU Extension


Blueberry : Lecanium scale
(revision date: 4/24/2015)

Lecanium scales are shiny brown insects found on twigs. Adults are 1/8"-1/4" in diameter and roughly turtle-shaped. They may have light markings or appear somewhat waxy. Crawlers (immature scales) are flatter. Heavily infested branches may be wilted, yellowish, or show other signs of stress. New growth may be stunted or lacking. Twigs and small branches may be killed. Lecanium scale is a common pest in the landscape and garden, infesting many plants including ornamentals and fruit trees. Feeding scales produce large amounts of honeydew, a sweet, sticky material which may attract ants or become covered with a growth of dark sooty mold. Honeydew and sooty mold can reduce fruit quality. Lecanium scale overwinters as immature scales on the twigs and branches of the host plants.
Management Options

Non-Chemical Management
  • Natural enemies such as ladybird beetles, green lacewings, and parasitic wasps help control scale populations. Avoid use of broad-spectrum insecticides which kill these and other beneficial insects.
  • Control honeydew-feeding ants which may protect scales from predators.
  • Hand-wipe to help control minor infestations.
  • Prune and destroy heavily infested branches, when practical.
Select non-chemical management options as your first choice!

Chemical Management

Apply oil sprays while plants are dormant and when temperatures are above freezing. Oils are effective in the delayed dormant period. Use superior type oil sprays only on overwintering nymphs.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • All Seasons Horticultural & Dormant Spray Oil Conc [Organic]
    Active ingredient: oil/pet distillate  |  EPA reg no: 4-80
  • R-T-U Year-Round Spray Oil
    Active ingredient: oil/pet distillate  |  EPA reg no: 6218-78
  • This list may not include all products registered for this use.
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Caption: Lecanium scales
Photo by: R.S. Byther