Sycamore Scale

How to identify it

• The scales are only about 1/16 inch long; look with a strong hand lens for yellow or orange scales in yellow to whitish leaf spots.^[1]
• Cottony white wax masses on bark or leaves can hold eggs or nymphs.^[1]
• Damage ranges from small, distorted leaves to abnormal flaking of smooth bark.^[1]

Look-alikes

Where it lives

It occurs only on sycamores, including California sycamore, Oriental sycamore and London plane, and reportedly isn't a pest on the eastern American sycamore.^[1]

US map: public records from 3 states since 1990 (GBIF). View the map

Biology and life cycle

It lives on foliage from leaf flush through fall and on tender bark all year.^[1]

Females lay eggs under white wax, and crawlers settle and swell into tiny football shapes.^[1]

Damage and signs

• Feeding causes leaf spotting and distortion that can look like disease, plus bark flaking.^[1]

Health risk

It feeds on sycamores only; UC IPM mentions no risk to people.^[1]

Control

When to call a professional

Management is complex because treatment works best at bud break, before any damage is visible.^[1]

Common questions

Why are my London plane tree's leaves spotted?

Sycamore scale feeding causes yellow to whitish spots that look like disease.^[1]

When is treatment most effective?

At bud break, before damage shows.^[1]

Sources

1. University of California Statewide IPM Program, “Pest Notes: Sycamore Scale (Publication 7409).” ipm.ucanr.edu/PMG/PESTNOTES/pn7409.html (accessed 2026-10-06)
2. iNaturalist, “Stomacoccus platani taxon page (order and family).” www.inaturalist.org/taxa/349754 (accessed 2026-10-06)