Juniper scales (U.S. National Collection of Scale Insects Photographs, USDA Agricultural Research Service, Bugwood.org)
- males: narrower, longer, whiter than females; oyster-shaped
- females: 1/16 inch; yellowish brown to white; circular
- immatures: crawlers (mobile stage) 3/64 inch; yellow orange; no wings
- immatures: nymphs (sessile stage) resemble adults, but are smaller
Host Plants, Diet & Damage
- juniper, cypress, false cypress, incense cedar, northern white cedar
- feed on the sap from needles/scales
- affected foliage turns “off-color,” yellow to brown
- new growth may stop
- serious infestations can cause tree death
Biology, Life Cycle & Damaging Life Stage
- overwinter as fertilized females
- crawlers present late-May to late-June
- males and females both form scale coverings and remain stationary; males become mobile during mating
- one generation per year, maybe two in warmer regions
- nymphs and adults are the damaging stages
- Keep trees healthy and stress free.
- Monitor scale crawlers from late-May to late-June using double sided tape wrapped around twigs.
- Apply horticultural oil to smother scales or scale crawlers when monitoring indicates crawlers are present.
- Apply a systemic dinotefuran soil drench, granules or bark band in May.
- Imidacloprid is ineffective against hard scales.