Insulanoplectron spinosum is endemic to the subantartic Snares Island of New Zealand,[1] where it is considered to be naturally uncommon.

[7] Although Insulanoplectron is distinct from other Rhaphidophoridae it has similarities in genital structure with Ischyroplectron hutton, another subantarctic weta.

Analysis of I. spinosum diet found that individuals consumed a variety of plants, invertebrates and one vertebrate species.

[4] While invertebrates detected in captured wētā include: Isopoda, Collembola, Tenebrionidae, Lepidoptera, Muscidae.

[4] In both male and female wētā Aves had been detected in all individuals regardless of age, this was determined to be seabird carcass.