Hemideina crassidens, commonly known as the Wellington tree wētā, is a large, flightless, nocturnal insect in the family Anostostomatidae.

This wētā species is endemic to New Zealand and populates regions in the southern half of North Island/Te Ika a Maui and the north-west of the South Island/Te Wai Pounamu.

These synonyms were created by Francis Walker, Walter Buller, Carl Brunner von Wattenwyl, John Salmon and William Colenso.

[11][12][13] A closely related native tree wētā, Hemideina thoracica, is widely distributed in the northern two-thirds of the North Island New Zealand.

[14] It has been suggested that H thoracica competitively excludes H. crassidens from warmer northern regions of the North Island.

[14] This contraction is likely to continue southwards during global warming, resulting in the displacement of H. crassidens from many lowland areas of central and southern North Island.

[11] They are generally herbivorous, feeding on the leaves, fruit and flowers of a wide range of trees and shrubs.

[18] Their bodies are smooth and shiny, the abdomen is ringed with contrasting bands of dark brownish to black and yellow, with a pale underside.

[18] This colouration is reminiscent of uniform of the Wellington rugby team, the Hurricanes, and can be used to distinguish it from the Auckland tree wētā (Hemideina thoracica).

[18] Rather than bore their own tree holes, H. crassidens inhabit natural crevices and cavities, or pre-existing tunnels that have been excavated by large wood-boring larva such as Aenetus virescens (Lepidoptera: Hepoalidae).

[24] Native trees and shrubs such manuka (Leptospermum scoparium), kanuka (Kunzea ericoides), ngaio (Myoporum laetum), kohekohe (Dysoxylum spectabile) and mahoe (Melicytus ramiflorus) are favoured by H.

[24] Suitable galleries have a narrow entrance hole (~20mm in diameter) in order to provide protection from predators such as birds.

[25] The holes are entered head first and exited in reverse so that the spines on their hind tibiae point outwards to defend from intruders.

[26][18] Hemideina crassidens is a polygynous insect in which males guard females that reside in tree cavities termed 'galleries'.