Gumtree scale

Gumtree scale insects form large colonies and cluster on stems, branches and leaves. They can cause defoliation, affect tree form and development, and weaken trees. They can be a significant pest in young eucalypt plantations.

Scientific name

Eriococcus species

Other names

  • Eriococcid scale
  • Felt scale
  • Rice bubble scale


  • Gumtree scale insects form large colonies. Their small capsules cluster on stems, branches and leaves.
  • They are pink, red, purple, green or brown. When squashed, they release a reddish-brown fluid.
  • Capsules are 2–4mm in diameter, reddish to white, and waxy, leathery or cottony. They have a small opening that allows newly hatched nymphs to emerge.
  • The insects feed under the capsules and may secrete a white cottony substance.
  • Leaves are often sticky from the honeydew excreted by the insects.
  • Sooty mould is often found with gumtree scale, turning leaves and branches black.
  • Ants are also commonly found with gumtree scale, feeding on the honeydew. They help to protect scale insects from predators and parasitoids and may move individuals to new feeding areas.


  • Widespread in Queensland, from temperate to subtropical regions


  • Spotted gum (Corymbia citriodora subspecies variegata)
  • Southern blue gum (Eucalyptus globulus)
  • Rose gum (E. grandis)
  • Blackbutt (E. pilularis)
  • Swamp mahogany (E. robusta)
  • Forest red gum (E. tereticornis)

Stressed trees are more susceptible to infestation.


  • The insects suck sap from trees, causing defoliation, especially on the lower and inner canopy of young trees.
  • Scale can affect overall tree form and development, especially of small or stressed trees.
  • It can weaken host trees and can be a significant pest in establishing eucalypt plantations.
  • Heavy infestations can kill trees.
  • Sooty mould, which grows on the honeydew, can affect photosynthesis by covering the leaves.


  • Scale colonies frequently consist of insects in various stages of development.
  • Each year, 2 to 5 generations are produced, depending on the temperature.
  • Females lay eggs under their capsules. After hatching, the young nymphs (crawlers) emerge through the opening and begin feeding and developing at a new site.
  • Crawlers are dispersed on wind currents, or as passengers on birds or ants.
  • Females often lose their legs and remain under their covering until death.
  • Adult males are small, mobile winged insects.


  • Gumtree scale insects have a wide range of natural predators including small birds and predatory insects (such as assassin bugs, lacewings, hoverflies, ladybird beetles, moths, flies and wasps).
  • Small infestations can be removed from the branch and squashed. Alternatively, branches can be removed and burnt.
  • Heavy infestations can be controlled by spraying or systemic stem injections.

Resources and research