Pest profile

Magnolia Scale

Neolecanium cornuparvum · Hemiptera: Coccidae[2]

Magnolia scale females grow to about 1/2 inch across; heavy infestations weaken and can kill magnolia branches.[1]

Large pinkish-tan waxy magnolia scales clustered on a twig
Large pinkish-tan waxy magnolia scales clustered on a twig. (c) Jody, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Females are about 1/2 inch across, smooth, rounded and pinkish-orange to brown under a waxy coating.[1]
  • Overwintering nymphs are dark gray with a red-brown ridge down the middle.[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

It feeds only on magnolia.[1]

US map: public records from 23 states since 1990 (GBIF).

Biology and life cycle

Nymphs overwinter on one- or two-year-old twigs and mature in late July to early August.[1]

Crawlers hatch in late August or early September; one generation a year.[1]

Damage and signs

  • It weakens branches and slows growth; honeydew and sooty mold foul the magnolia and plants below, and heavy infestations can kill branches.[1]

Health risk

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

Control

Biological control

Lady beetles and tiny parasitic wasps usually keep scales below damaging numbers.[1]

Pesticides

Populations build fast, so treat the same season you see them; horticultural oil in late fall and early spring smothers overwintering nymphs.[1]

Insecticidal soap or horticultural oil timed to active crawlers has minimal impact on natural enemies.[1]

Common questions

What are the big waxy bumps on my magnolia?
Likely magnolia scale; females are about 1/2 inch across and pinkish to brown.[1]
Why is everything under my magnolia sticky and black?
Magnolia scale honeydew grows sooty mold on the tree and plants below.[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, “Neolecanium cornuparvum taxon page (order and family).” www.inaturalist.org/taxa/507879 (accessed 2026-10-06)

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