Auckland Zoo is releasing 150 giant weta on to a pest-free island in the Hauraki Gulf.
The weta punga is one of the world's heaviest insects and can weigh as much as a sparrow.
All offspring have been bred from six male and six female weta punga, brought from Little Barrier Island, the only place they are now naturally found.
The zoo says the breeding success is because of new techniques involving rearing the insects in groups as well as individually, in a special temperature-controlled weta facility.
The giant weta are being released on Motuora Island on Thursday.