Deinacrida fallai or the Poor Knights giant wētā is a species of insect in the family Anostostomatidae.

[2] It is the second largest wētā species in the world,[2] with females weighing up to 40g and measuring up to 73mm (2.87 inches) in length.

[2] Although D. fallai are one of the largest/heaviest insect species, they have relatively agile movements and are easily able to jump long distances up and down tree trunks and branches.

[2] They also quickly move their legs up and down to make a crackling or rasping sound over their stridulatory apparatus for the duration of disturbance.

[2] Nymphs up to the fifth instar display protective behaviours by burrowing head first into the soil, leaving only their hind tibia and tarsi exposed.

[2] They are forest dwelling, arboreal insects,[3] spending most of their time on tree trunks and branches at night.

[8] During the day they spend their time above ground, perching in foliage or hiding in the lose bark of pohutukawa.

[3] They thrive in the undisturbed pohutukawa forests on these islands where they co-exist with low to moderate density populations of tuatara.

[2] Wētā studied in captivity displayed no courtship behaviour and sex recognition appeared to be through contact alone.

This mating position causes the male to twist vertically, creating a 45- to 90-degree angle between their bodies and is sometimes assumed instantly at the beginning of copulation.

[2] The male produces and transfers a single spermatophore to the underside of the females sub-genital plate during each copulation.

[2] Females can lay eggs throughout their life at any time of the year, provided the ambient temperature is higher than 10 °C.

[2] There is considerable variation in the time that each individual spends at each nymphal instar, ranging from 3 to 13 weeks.

[2] D. fallai use an abdomino-femoral mechanism to produce sound by rubbing their hind legs against the tergites on their abdomen.

[10] The leading edge of the convex crescent ridge is separated by a longitudinal groove that forms two lips.

[10] Because the femur pegs are arranged in a radial fashion, they will rub laterally against the ridges on the tergite as the wētā moves its legs past its abdomen.

[10] When the wētā moves its back legs up and down against this stridulatory apparatus it creates a crackling or rasping sound that strongly deters potential predators.

[2] When the wētā is annoyed, abdominal segment contractions cause the spines to rub together, producing a hissing sound.

[3] Deinacrida fallai form a monophyletic clade with two other northern arboreal wētā species: D. heteracantha and D.

[5] Deinacrida fallai are one of many giant wētā species that are protected under the Seventh Schedule of the 1953 Wildlife Act.

[5] Accidental introduction of rodents to the Poor Knights Islands would endanger the entire species by gravely reducing or eradicating D.

[5] Investigation is required in order to assess feasibility of the potential increase of D. fallai populations by introducing this species to other locations.