Shield bugs are also known as stink bugs, referring to the strong smell they emit when feeling threatened. This chemical is likely to deter predators from eating them.
The New Zealand vegetable bug, (or Australasian Green Shield bug) is a native bug found throughout New Zealand. It is a bright apple green colour, although it has also been found in yellow colour morphs. Using their piercing and sucking mouthparts, this bug feeds on the berries and sap of a range of native plants including karamū and pūriri.
During winter, adults will hide amongst foliage and under bark to escape the cold. Sometimes they can also be seen basking in the sun when conditions are right. Females will lay eggs in neat clusters, often laying several clutches during the year. The nymphs which hatch from the eggs are small, darkly coloured and wingless. As the nymphs go through their growth stages, their colour starts changing to the final green adult colour.
Check these links for more info on Shield Bugs in NZ
iNaturalist.nz: Observations of Glaucias amyoti
Wikipedia: Information on Weelus amyoti; Information on Shield Bugss (general)
Landcare Research: Green Shield Bug Fact Sheet
Click on the image to visit the official iNaturalist.nz observation.