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Juniper Scale

Characteristics:

  • Eggs: Females lay eggs in May which hatch in about 2 weeks.
  • Larvae: Larvae are yellowish and about 1.5 millimetre in length.
  • Adults: Adults attach themselves to the juniper and form a protective waxy scale or shell casing. Mature males are whitish and have an elongated body. Mature females may be white to brown in colour and 1.5 millimetres in diameter with a dark centre. Females overwinter inside the scale and lay eggs the following year.

Identifying infestations:

  • Yellow or browning needles: The plant’s needles may turn yellow or brown as the scale insects suck sap from the juniper, arborvitae, cedar, or cypress tree.
  • Formation of scales on branches: Small, white, round or oval specks on twigs and foilage.
  • Black sooty mould: Black, sooty mould often develops on honeydew found at the infestation site.

IPM Toolkit:

  • Preventive tools:
    • Avoid excess nitrogen in the soil, which may encourage rapid plant growth which attracts high populations of scales.
  • Physical tools:
    • Scrape the scale’s hard shell casing off of twigs and foliage.
    • Prune and destroy severely infested limbs.
    • Birds and some insects will eat scale larvae when populations are low.
  • Least toxic chemical tools:
    • Following label directions, apply Dormant Oil on larvae before shell casings develop (usually before mid-June)