Pest profile

Cottony Cushion Scale

Icerya purchasi · Hemiptera: Monophlebidae[2]

Cottony cushion scale is usually kept in check by the vedalia beetle and a parasitic fly; problems mostly follow insecticide use, dust or ants.[1]

Female cottony cushion scale, an orange-brown scale insect attached to a large white, fluted cottony egg sac
Female cottony cushion scale, an orange-brown scale insect attached to a large white, fluted cottony egg sac. Photo: Jesse Rorabaugh, public domain (CC0), via iNaturalist

How to identify it

  • Adult females are orangish brown and carry a long, fluted white cottony egg sac; together they can reach almost 1/2 inch.[1]
  • The egg sac holds 600 to 800 red eggs.[1]
  • Crawlers are red with black legs and antennae and settle along leaf veins.[1]
  • Unlike most scales, it keeps its legs and can move throughout its life.[1]

Look-alikes

Look-alikeHow to tell them apart
Vedalia beetle larvaeReddish vedalia larvae feed on top of the egg sacs; young ones have red legs, while scale crawlers have black legs and antennae.[1]

Where it lives

Common hosts in California include citrus, cocculus, nandina and pittosporum.[1]

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

Biology and life cycle

Eggs hatch in a few days in warm weather but can take two months in winter.[1]

Young scales settle on twigs and leaf veins and move to branches and trunk as they grow; females don't need to mate.[1]

There are two to three generations a year, and the life cycle takes about three months in warm weather.[1]

Damage and signs

  • It sucks sap from leaves, twigs, branches and trunks; extremely heavy infestations cause leaf drop and twig dieback.[1]
  • It excretes honeydew, which brings black sooty mold and ants, and heavy populations can cut citrus yields.[1]

Health risk

It feeds only on plants; UC IPM describes no risk to people.[1]

Control

Biological control

Look for vedalia beetles, their red eggs and larvae on egg sacs, or round exit holes of the Cryptochaetum fly; if present, no spray is needed.[1]

Keep ants out of trees with sticky trunk bands on a protective wrap, or with ant baits, so natural enemies can work.[1]

Pesticides

Don't use imidacloprid: it doesn't kill cottony cushion scale, but it poisons vedalia beetles, and outbreaks have followed its use.[1]

If natural enemies are absent and crawlers are active, horticultural oil is least disruptive; sticky tape around twigs shows when crawlers hatch.[1]

Common questions

What is the white fluted insect on my citrus?
Likely cottony cushion scale; the ridged white cottony egg sac attached to an orange-brown female is its trademark.[1]
Should I spray cottony cushion scale?
Usually not. Natural enemies give excellent control unless insecticides, dust or ants disrupt them.[1]
Why is my cocculus always infested?
Vedalia beetles avoid Cocculus laurifolius, so it is often heavily infested, especially away from the coast.[1]

Sources

  1. University of California Statewide IPM Program, “Pest Notes: Cottony Cushion Scale (Publication 7410).” ipm.ucanr.edu/PMG/PESTNOTES/pn7410.html (accessed 2026-10-06)
  2. iNaturalist, “Icerya purchasi taxon page (order and family).” www.inaturalist.org/taxa/60921 (accessed 2026-10-06)

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