Citrus gall wasp (CGW)

Citrus gall wasp (Bruchophagus fellis) is a citrus pest and a threat to the citrus industry in South Australia.

This pest damages citrus production by producing stem thickenings (galls) that can weaken trees, making them unproductive.

Heavy infestations of Citrus gall wasp can reduce crop yield and cause branch dieback.

What Citrus gall wasps looks like

Adult Citrus gall wasps are dark brown/black in colour and are less than 3mm in size (which can make them hard to spot).

Galls in newly infested branches are small and difficult to spot. Check for light-green coloured shoots coming out at right angles from branches (spring to early autumn).

Citrus gall wasps cause woody galls on citrus twigs. Photo: Pia Scanlon, Western Australian Department of Primary Industries.
Citrus gall wasps cause woody galls on citrus twigs. Photo: Pia Scanlon, Western Australian Department of Primary Industries.
The citrus gall wasp hatches in spring. Photo: NSW Department of Primary Industries.
The citrus gall wasp hatches in spring. Photo: NSW Department of Primary Industries.

How Citrus gall wasps spread

While its natural host is the Australian finger lime, citrus gall wasp has become adapted to other citrus varieties such as lemons and grapefruit. It spreads through orchards and backyard citrus trees, usually as a result of the introduction of infested citrus plants and the lack of monitoring of gall development in branches.

Citrus gall wasps have a limited flying range meaning infestations within a property occur by the close presence of infested citrus trees, including across the fence of urban properties. It can spread across long distances by wind and by movement of infested trees or by untreated infested branches.

How they can be controlled

An integrated management approach is important to achieve effective and long-lasting results.

Citrus tree owners need to:

  • monitor all citrus trees on your property by looking for stem thickenings (galls) that signal citrus gall wasp infestation
  • target the different stages of the citrus gall wasp lifecycle
  • involve neighbours in an area wide management approach to provide the best results.

Learn more in the Citrus Gall Wasp Fact Sheet

More information

You can contact your local nursery or garden centre for the appropriate controls and treatments.

Page Last Reviewed: 06 Nov 2019
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