Granulate ambrosia beetle

This unwanted pest beetle was detected in Auckland in February 2019. Biosecurity New Zealand is supporting research on the species and developing tools to help manage it. Tell us if you see any damage caused by the beetles.

Spread of the granulate ambrosia beetle in NZ

The granulate ambrosia beetle (Xylosandrus crassiusculus) was detected in Auckland in February 2019. Biosecurity New Zealand has done extensive ground surveys to determine the distribution of the beetles across the Auckland region. The beetle was found in native and exotic species in 7 areas within Auckland. It has not been detected outside the Auckland region.

The Auckland detection was the first time the beetle has been found in New Zealand. However, evidence suggests it may have been in the country for at least 3 years.

Distribution elsewhere in the world

The granulate ambrosia beetle is regarded as a serious pest overseas. It is known to damage a wide range of broadleaf trees, including horticultural species. It can also spread damaging fungi when they are present in the area.

The beetle is native to tropical and subtropical East Asia. It has been found in many areas in the world, including Africa, the USA, Central America, Europe, some Pacific Islands, and most recently in Queensland, Australia.

Granulate ambrosia beetle fact sheet issued March 2019 [PDF, 427 KB]

The risk to New Zealand

Biosecurity New Zealand is assessing the potential risk from the beetle to New Zealand native trees and planted trees and shrubs. There is no evidence that any damaging fungi have been transmitted by the granulate ambrosia beetle in New Zealand.

What we're doing 

Biosecurity New Zealand has worked with local authorities to identify the extent of the spread, using lure traps and ground surveys of trees showing discolouration or dieback symptoms.

Unfortunately, no tools exist internationally to manage the beetle due to its special reproductive behaviour and cryptic lifestyle.

Biosecurity New Zealand is working closely with Crown Research Institutes, Scion, and Plant and Food Research, to increase our knowledge about the granulate ambrosia beetle and its impacts. This work includes the beetle’s biology and flight activity and the development of new and improved lures and trials. This will help determine how susceptible at-risk native and of-interest industry species are to beetle infestation. 

What you can do

We need you to tell us if you think you see any damage caused by the pest or the beetle itself.

A tell-tale sign is distinctive protrusions of frass (compacted sawdust) from bark that look like toothpicks. They are caused by the beetles pushing frass out of tunnels bored into the trees. Other symptoms include sap oozing from the tunnel entrances and branch dieback.

If you see the beetle or any sign of frass on trees:

  • take a photo
  • phone our pests and diseases hotline on 0800 80 99 66.

Media release 25 March 2019: Public asked to help with beetle surveillance

How to identify the beetle and frass

tree trunk with worm-like sawdust protrusions
Sawdust strings protruding from the trunk of a tree. Image: with permission from Jiri Hulcr, University of Florida.
Top view of an adult female granulate ambrosia beetle. Image: Emma Scheltma, MPI Plant Health and Environment Laboratory
Top view of an adult female granulate ambrosia beetle. Image: Emma Scheltma, MPI Plant Health and Environment Laboratory
Side view of an adult female granulate ambrosia beetle. Image: Emma Scheltma, MPI Plant Health and Environment Laboratory
Side view of an adult female granulate ambrosia beetle. Image: Emma Scheltma, MPI Plant Health and Environment Laboratory
under side view of an adult female granulate ambrosia beetle. Image: Emma Scheltma, MPI Plant Health and Environment Laboratory
Under side view of an adult female granulate ambrosia beetle. Image: Emma Scheltma, MPI Plant Health and Environment Laboratory
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