The evolutionary relationships of the New Zealand representatives of the family Anostostomatidae were examined using DNA sequence data. All species of giant weta (Deinacrida), tree weta (Hemideina) and tusked weta (Anisoura, Motuweta) were included in the study plus 4 taxa from the large genus of New Zealand ground weta (Hemiandrus). Sequence data from 2 mitochondrial genes (COI and 12S) were analysed to obtain a hypothesis of the evolution of these species. The 3 New Zealand tusked weta species formed a monophyletic clade with respect to the ground weta and to the giant and tree weta clad0e. We found no support for the placement of Anisoura nicobarica Ander within Deinacridinae as has previously been suggested. The giant and tree weta (Deinacridinae) consistently formed a monophyletic clade with respect to the tusked and ground weta. However, we found little support in our data for the reciprocal monophyly of the tree and giant weta genera. The tree weta Hemideina broughi (Buller) appears to be more closely related to Deinacrida pluvialis Gibbs and D. talpa Gibbs than to any other Hemideina species. The deinacridine radiation of leaf-eating weta comprises at least 6 comparatively ancient lineages (Hemideina and Deinacrida). Habitat-specialisation in South Island appears to have evolved in response to habitat diversification associated with Pliocene mountain building.