Arborvitae: Spruce bud scale

categories: Arborvitae Arborvitae Insects Conifers Ornamentals

revision date: 2024-06-05 08:28

Spruce bud scale.
Spruce bud scale
Photo by: A.L. Antonelli


Spruce bud scales are shiny brown insects found on the twigs. Heavily infested plants may appear yellowish or show other signs of stress. New growth may be stunted or lacking. Adults are 1⁄8″-1⁄4″ in diameter and roughly turtle-shaped. Crawlers (immature scales) are flatter. Scales produce large amounts of honeydew, a sweet, sticky material which may attract ants or become covered with a growth of dark sooty mold. Spruce bud scale is a common pest in the landscape, infesting spruce and pine as well as arborvitae.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

  • Natural enemies such as ladybird beetles and green lacewings help control scale populations. Avoid use of broad-spectrum insecticides which kill these and other beneficial insects.
  • Hand-wipe to help control minor infestations.
  • Prune and destroy heavily infested branches, when practical.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

Monitor for immature crawlers when new shoots expand. Apply shortly after crawlers are detected. Do not apply soap products to plants stressed by drought or when tender new foliage is present. Do not apply soaps in full sun or when temperatures exceed 90° F. Homeowners should not make foliar applications to trees over 10 ft. tall. Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Approved Pesticides

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.