Tree growers urged to check for new wood-boring beetle

The granulate ambrosia beetle and its ‘frass’.

Avocado and fruit tree growers are being asked to be on the lookout for signs of a serious new wood-boring pest that has been discovered in five areas of Auckland since February.

Biosecurity New Zealand said the granulate ambrosia beetle had been found at Blockhouse Bay, Kumeu, Titirangi and two sites in Riverhead – the first time the pest has been detected in this country.

The beetle is regarded as a serious pest overseas, and is known to damage a wide range of broadleaf trees, including avocado, plum, peach, persimmon and pear, as well as common trees such as oak, ficus, eucalyptus, magnolia, acacia, and casuarina.

While it is unclear how the beetle arrived in NZ, evidence suggests it may have been here for at least two years. Because the granulate ambrosia beetle lives under bark, it is difficult to detect, but a tell-tale sign is distinctive stick-like protusions of compacted sawdust poking  out of the bark that resemble toothpicks or matchsticks, known as frass. Other symptoms include sap oozing from tunnel entrances and branch dieback, and mainly weak or diseased trees are affected.

Biosecurity NZ is asking members of the public to report any sign of the pest so that traps can be placed and further inspections carried out. Biosecurity surveillance and incursion manager Brendan Gould said officials were working with local authorities to identify the extent of the spread.

“We need to know if New Zealand has a wider population, which is why we are asking the public to report any possible sightings,” he said.

Anyone who believes they have seen the granulate ambrosia beetle or any sign of frass on trees should take a photo and call Biosecurity New Zealand’s exotic pests and diseases hotline on 0800 809966.


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