Cottony Maple Scale
Immature cottony maple scales and egg mass (Raymond Gill, California Department of Agriculture and Food, Bugwood.org)
- females: 1/8 inch; convex; pale to dark brown
- immatures: crawlers (mobile stage) ~ 3/64 inch, yellow orange; no wings
- immatures: nymphs: smaller, flattened and oval; translucent yellowish; found on leaves
- egg sacs: white/cottony; grow from under females
Host Plants, Diet & Damage
- most common on maple; many hosts
- feed on plant sap from leaves/twigs/small branches
- infestations produce unsightly cottony masses
- branch and twig dieback; early leaf drop
- honeydew production; sooty mold
Biology, Life Cycle & Damaging Life Stage
- overwinter as mated, 2nd instar nymphs on twigs and branches
- cottony egg masses grow in spring
- eggs hatch June through July
- crawlers settle on the undersides of leaves near the midrib or veins
- mating occurs in late summer
- mated females migrate to twigs and branches to overwinter
- one generation per year
- nymphs and adults are the damaging stages
- 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.