Integrated Pest Management
Black Pineleaf Scale
Dynaspidiotus californica
Black pineleaf scales (Whitney Cranshaw, Colorado State University, Bugwood.org)
Black pineleaf scale infestation (Steven Katovich, USDA Forest Service, Bugwood.org)
Black pineleaf scale damage (Susan Rose, Bugwood.org)
Pest Description
- adults: 5/64 inch; gray to black oval shells
- immatures: crawlers (mobile stage) 3/64 inch; yellow orange; no wings
- immatures: nymphs (sessile stage) resemble adults, but are smaller
Host Plants, Diet & Damage
- pine (common on Austrian, Scotch, and mugo) and Douglas-fir
- feed on the sap from needles
- affected needles can be blotchy yellow
- thinning crowns with yellowing/browning needles
- presence of scales can also be unsightly if heavy
- serious infestations can cause needle drop or tree death
Biology, Life Cycle & Damaging Life Stage
- overwinter as immature scales
- mating occurs in June
- eggs are laid in late-June and early-July
- eggs are laid under the female scale
- crawlers are present from mid- to late-July
- crawlers blow to new locations via wind currents
- crawlers develop an outer shell and remain stationary
- one generation per year
- nymphs and adults are the damaging stages
IPM Recommendations
- Keep trees healthy and stress free.
- Monitor scale populations on pines.
- Monitor scale crawlers from early to mid-July 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 June.
Imidacloprid is ineffective against hard scales.