Pest profile

Calico Scale

Eulecanium cerasorum · Hemiptera: Coccidae[2]

Calico scale's most obvious sign is heavy sticky honeydew and black sooty mold on trees and anything beneath them.[1]

Calico scale, a puffy round scale blotched black and white, on a twig
Calico scale, a puffy round scale blotched black and white, on a twig. (c) Brendan O'Loughlin, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Mature females are about 1/4 inch, puffy and globular, blotched black, white and brown.[1]
  • Crawlers start out pink and turn yellow as they age.[1]

Where it lives

It has a broad host range, including crabapple, elm, honeylocust, maple, oak, dogwood, redbud and stone fruit trees.[1]

US map: public records from 18 states since 1990 (GBIF).

Biology and life cycle

It overwinters as crawlers on branches; females swell in spring and lay eggs by mid-May.[1]

Damage and signs

  • Feeding causes leaf yellowing and twig dieback, and honeydew draws ants and wasps.[1]

Health risk

It feeds on trees; UK Extension mentions no risk to people.[1]

Control

Traps and physical control

Scrubbing branches with brushes can physically remove the scales, though it may take repeated effort.[1]

Pesticides

Systemic insecticides have had variable results, so control usually targets the crawlers.[1]

Common questions

What's dripping sticky sap from my honeylocust?
Possibly honeydew from calico scale.[1]
Will a systemic treatment work?
Results have been variable; crawler treatments are the usual focus.[1]

Sources

  1. University of Kentucky Entomology (ENTFACT), “The Challenges of Calico Scale Control (ENTFACT-466).” entomology.mgcafe.uky.edu/ef466 (accessed 2026-10-06)
  2. iNaturalist, “Eulecanium cerasorum taxon page (order and family).” www.inaturalist.org/taxa/882990 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.