Black scale in olives

Page last updated: Monday, 14 May 2018 - 2:44pm

Please note: This content may be out of date and is currently under review.

Chemical control

  • In conventional olive groves, growers use a combination of narrow range mineral or petroleum oils and/or an insecticide such as an insect growth regulator to control black scale, while organic growers are restricted to oils.
  • Correct timing of sprays is essential for successful control, since insecticides are only effective against young scales (crawlers, first and second instars).
  • Check the APVMA and Infopest websites for the latest in chemical control.

Biological control

  • Black scale has been the subject of biological control projects in the Australian citrus industry since 1902. From 1902 to 1947, 24 species of beneficial insects (22 parasites, two predators) were released for its control.
  • These included Metaphycus anneckei in 1902 from South Africa and M. helvolus 1943–47 from the USA. From 1998 to 2003, M. helvolus and M. lounsburyi were released in citrus as part of a Horticulture Australia Ltd-funded project.
  • Surveys as part of a Rural Industries Research and Development Corporation project in WA showed that the egg predator, Scutellista caerulea, is most common. M. helvolus and M. anneckei are poorly established.
  • The effectiveness of S. caerulea is limited, because populations build up too late to prevent scale outbreaks.
  • Establishment of M. helvolus and M. lounsburyi in olives is recommended. However, there may be problems in obtaining insects commercially for release.
  • General predators such as lacewings and ladybirds also feed on black scale.


  • Ant control is required where growers are interested in biological control, as ants harvest honeydew from black scale and protect the scale from parasites and predators. No insecticides are presently registered in olives for this purpose.
  • Overseas, bait stations with liquid sugar and boric acid (organically acceptable) are available for ant control.

Contact information

Stewart Learmonth
+61 (0)8 9777 0167
Sonya Broughton
+61 (0)8 9368 3271


Sonya Broughton