Up to 100 Mahoenui giant weta - one of the world's largest insects - were introduced to Maungatautari yesterday in a bid to bolster the species' survival prospects.
The Mahoenui giant weta were moved from the Mahoenui giant weta Scientific Reserve in King Country.
It is the first time this species of weta has been introduced into a mammal-free, native forest on the mainland.
Landcare Research's Dr Corinne Watts said Maungatautari should provide an ideal habitat for the giant weta.
"In the two years since Maungatautari's southern enclosure was cleared of pest mammals it has been pleasing to see that ground-dwelling beetles and tree, ground and cave weta have increased in abundance," she said.
It is expected the introduction will increase the weta population, which is under threat. The insects can weigh as much as 25g and measure up to 65mm.
Maungatautari Ecological Island Trust general manager Malcolm Anderson said it was the "last hope" for the species to live in its natural environment.
Since 1989, over 2000 Mahoenui giant weta have been moved to seven mainland and island sites in New Zealand, but appear to be flourishing at only two sites.
There are plans to release more weta at Maungatautari next year.