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)