Pest profile

Cottony Maple Scale

Pulvinaria innumerabilis (iNaturalist: Neopulvinaria innumerabilis) · Hemiptera: Coccidae[2]

The white cotton balls on silver maple twigs in June are cottony maple scale egg sacs; natural enemies usually keep it in check.[1]

Brown cottony maple scale female with a large white cottony egg sac on a twig
Brown cottony maple scale female with a large white cottony egg sac on a twig. Photo: Adam Kranz, public domain (CC0), via iNaturalist

How to identify it

  • The obvious stage is the brown female with a large white cottony egg sac protruding from the rear.[1]
  • Females without egg sacs are about 1/8 inch, flat, soft and pale to dark brown.[1]

Look-alikes

Look-alikeHow to tell them apart
Other scale insectsScale species differ in timing, so identify the species to know when crawlers are active.[1]

Where it lives

Hosts include maples, especially silver maple, honeylocust, linden and other hardwoods.[1]

US map: public records from 28 states since 1990 (GBIF).

Biology and life cycle

Young females overwinter on twigs, grow in May, and form egg sacs by early June.[1]

Crawlers hatch in late June to early July and feed under leaves; one generation a year.[1]

Damage and signs

  • Large amounts of honeydew support sooty mold, but there's no significant damage to plant health.[1]

Health risk

Scales feed only on plants; Minnesota Extension mentions no risk to people.[1]

Control

Biological control

Natural enemies usually control it, so it seldom needs management.[1]

Pesticides

If needed, horticultural oil in late fall and early spring smothers overwintering females.[1]

Common questions

What are the white cotton balls on my maple twigs?
Cottony maple scale egg sacs, which appear by early June.[1]
Will it hurt my maple?
Not significantly; natural enemies usually control it.[1]

Sources

  1. University of Minnesota Extension, “Scale insects (Yard and garden insects).” extension.umn.edu/garden-and-home/yard-and-garden/yard-and-garden-insects/scale-insects (accessed 2026-10-06)
  2. iNaturalist, “Neopulvinaria innumerabilis taxon page (order and family).” www.inaturalist.org/taxa/1018223 (accessed 2026-10-06)

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