Pest profile

Obscure Scale

Melanaspis obscura · Hemiptera: Diaspididae[2]

Obscure scale is named for being hard to see; it can cause branch dieback and sunken, disfigured bark.[1]

Obscure scales, overlapping dirty gray scale covers on tree bark
Obscure scales, overlapping dirty gray scale covers on tree bark. (c) Zihao Wang, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Female covers are about 1/8 inch, dirty gray, with an off-center black cap; the yellow or cream insect is underneath.[1]
  • Up close, infested bark can look dusted with ash or silver glitter.[1]

Where it lives

It's found on oaks (especially pin and willow oaks), beech, dogwood, hackberry, hickory, maple, pecan and willow.[1]

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

Biology and life cycle

It overwinters as nymphs on branches; females lay about 50 pink eggs.[1]

Crawlers emerge over a long stretch from early summer to the end of August.[1]

Damage and signs

  • Stressed trees show leaf drop and branch dieback, and the bark becomes sunken where scales fed.[1]

Health risk

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

Control

Pesticides

Treat crawlers in May or July with a pyrethroid or oil-based insecticide, or use a systemic dinotefuran application.[1]

Common questions

What's the gray crust on my oak's bark?
Possibly obscure scale, which can look like ash or silver glitter.[1]
Why is it called obscure scale?
Because it's hard to see on bark.[1]

Sources

  1. University of Kentucky Entomology (ENTFACT), “Obscure Scale (ENTFACT-432).” entomology.mgcafe.uky.edu/ef432 (accessed 2026-10-06)
  2. iNaturalist, “Melanaspis obscura taxon page (order and family).” www.inaturalist.org/taxa/319358 (accessed 2026-10-06)

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