An avocado tree-loving beetle, regarded as a serious pest overseas, has been discovered in Auckland.
The wood-boring granulate ambrosia beetle has been detected in four Auckland areas since late February, according to Biosecurity New Zealand.
The beetle is known to feed on a wide range of broadleaf trees, including horticultural species such as avocado, and can spread fungal diseases.
The discovery of the beetle is the first of its kind in New Zealand, but Biosecurity NZ said early evidence suggested it may have been in the country for at least two years.
Biosecurity NZ surveillance and incursion manager Brendon Gould said the potential risk of the beetle being in the country was being assessed.
"We need to know if New Zealand has a wider population, which is why we are asking the public to report any possible sightings."
Mr Gould said the beetle lives under bark, making it difficult to detect.
However, he said 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.
Mr Gould said officials were working with local authorities to identify the extent of the spread, including inspecting known host trees and placing lured traps around the detection sites.
Biosecurity New Zealand has also directed the removal of infested oak trees at one of the sites.
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.