Integrated Pest Management
Fletcher Scale
Parthenolecanium fletcheri
Fletcher scales (Whitney Cranshaw, Colorado State University, Bugwood.org)
Fletcher scale nymphs (J. A. Davidson, Bugwood.org)
Fletcher scale eggs under adult female (Lorraine Graney, Bartlett Tree Experts, Bugwood.org)
Pest Description
- adults: highly variable; females are ~ 1/8 inch; globular; yellowish to dark brown; mottled; males winged and fly-like
- immatures: crawlers (mobile stage) are tiny (3/64 inch), yellow orange and wingless
- immatures: nymphs are smaller, flattened and oval to globose; brownish yellow to dark brown
Host Plants, Diet & Damage
- arborvitae, yew, juniper
- feed on plant sap from twigs, small branches and leaves
- can cause tree stress and decline
- honeydew production leads to sooty mold on leaves and branches
Biology, Life Cycle & Damaging Life Stage
- overwinter as 2nd instar nymphs on twigs, needles or bud scales
- around May, females reach maturity and mate
- can reproduce without mating
- eggs are laid under the female body
- egg hatch occurs from mid-June through late-July
- crawlers settle on needles, bud scales or branches
- one generation per year
- nymphs and adults are the damaging stages
IPM Recommendations
- Manage trees to improve or maintain health.
- Monitor scale populations on host plants.
- Apply an insecticide (carbamate; horticultural oil; insecticidal soap; organophosphate; pyrethroid) to coincide with scale crawler activity.
- Apply a systemic neonicitinoid in spring after leaves have expanded.
For more information, see our Soft Scales in Utah Landscapes fact sheet.