Tuatara: Volume 6, Issue 1, January 1956
A Key to the Tree and Ground Wetas of New Zealand
A Key to the Tree and Ground Wetas of New Zealand
Insects popularly known in New Zealand by their Maori name of ‘weta’ belong to the Order Orthoptera and in classification fall into the two families Henicidae Karny, 1937, and Rhaphidophoridae Kirby, 1883. The former family includes all those forms generally referred to as tree or ground wetas which, according to Maori legend, are really the ‘true’ wetas. These are the ‘Taipos’ of the West Coast of the South Island: ‘taipo’, which comes from the Maori, means ‘the devil who comes by night’, and is really a highly descriptive term for the bush-weta. The Rhaphidophoridae includes those insects generally referred to as ‘cave wetas’ though many of their species are also free-living in the forests and are often found on trees.
Many of the species of Henicidae in New Zealand are very large formidable-looking insects; they are, in fact, among the largest insects in the world. In spite of their rather terrifying appearance they are, however, retiring insects which largely hide by day and come out to feed at night. They are seldom aggressive and will only bite with their mandibles if seriously molested, and though the bite from a medium-size weta may be painful only the larger specimens can puncture the skin and draw blood. Normally, when disturbed, these insects tend to run away, seldom showing fight. They run somewhat clumsily but fairly rapidly, seeking out new shelter. Their normal means of defence consists in raising the hind legs high above the abdomen, then drawing them suddenly downwards and backwards so that the large sharp spines on the tibiae can be brought to bear against the attacker. This vigorous raising and lowering of the hind legs produces at the same time a shrill rasping sound from the sounding organ. The overall effect can be quite frightening and is generally sufficient to deter another animal, such as a cat, dog or bird, from an immediate attack upon the insect, which uses this opportunity to make a rapid get-away. A scratch inflicted by the tibial spines of a weta can be quite dangerous due to infection from decaying material amongst which the insect may have been moving.
In handling wetas, to avoid as fas [sic] as possible being scratched by the hind legs, the insect should be grasped firmly by the thorax, just behind the head, when the hand will be well out of harm's way.page 20
Fig. 1: Diagrammitic outline of a Deinacrid weta from above. (T1, Tergum of prothorax [pronotum]; T2, Tergum of mesothorax [metanotum]; T3, Tergum of metathorax [metanotum].) Fig. 2: Enlarged diagrammatic view from below of female genital region of a Deinacrid weta. Fig. 3: Enlarged diagrammatic view from below of male genital region of a Deinacrid weta.
The large wetas belonging to the genera Deinacrida and Hemideina seldom jump, but the smaller species of Hemiandrus and Zealandosandrus jump vigorously and will often travel considerable distances in one leap.
The species of Hemideina inhabit foliage and burrow in decaying trunks and branches of trees or in fallen logs, while those of Deinacrida occur amongst foliage or amongst stones, often on high mountains. Hemiandrus species are usually found inhabiting small burrows in soft banks and occasionally fallen logs, whereas Zealandosandrus species are nearly always found in association with fallen trees and logs or in burrows in the earth under stones on mountain-sides.
Super Family Gryllacridoidea
|1||Body nearly straight longitudinally, broadest across anterior part of pronotum; antennal bases widely separated; tarsal segments with arolia (tarsal pads) on their lower surfaces.
|Body arched longitudinally, broadest across posterior part of mesonotum; antennal bases close together; tarsal segments without arolia.
|2||Auditory pits present on both sides of each fore tibia.||— 3|
|Auditory pits absent from tibia.||— 5|
|3||Proternum bearing a pair of spines, spine-like lobes or rounded protuberances.||— 4|
|Prosternum without either spines or lobes.
Genus Hemideina Walker 1869
|4||Prosternum with two sharp spines or spine-like lobes.
Genus Deinacrida White 1842
|Prosternum with two rounded protuberances; fore femur with single superior prolateral apical spine, middle and hind femora each with two superior apical spines.
Genus Deinacridopsis Ander, 1939
Single species D. connectens Ander, 1939
|5||Species moderately well clothed with setae on sides of body and on legs; females with ovipositor extremely short, hardly as long as the styles, and generally with paired processes arising from the sixth abdominal sternite; males with the ninth abdominal tergite porrected or emarginate posteriorly.
Genus Hemiandrus Ander 1938
|Species only sparsely clothed with setae on either body or lengs; females with ovipositor as long as or longer than abdomen and without processes on sixth abdominal sternite; males with ninth abdominal tergite normal or slightly concave posteriorly, never emarginate.
Genus Zealandosandrus Salmon 1950
|6||Posterior margins of the terga markedly rugose or ornamented with granules.||— 7|
|The terga not so, more or less plain.||— 9page 22|
|7||Middle femora each with a pair of apical spines.||— 8|
|Middle femora each with single prolateral, minute, inferior apical spine; moderate to small species with the posterior segmental margins markedly rugose.
D. tibiospina Salmon 1950
|8||Fore femora each with a single prolateral apical spine; large species with the posterior segmental margins ornamented with transverse rows of granules.
D. rugosa Buller 1871
|Fore femora without spines; small species with the posterior segmental margins rugose, that of the pronotum marked to give a ‘notched’ appearance.
D. carinata Salmon 1950
|9||Hind femora each with numerous superior spines; superior spines of hind tibiae small, thin, and often curved.
D. sonitospina Salmon 1950
|Hind femora without superior spines.||— 10|
|10||Superior spines of each hind tibia longer than width of tibia; tibiae themselves slender and of uneven or irregular outline, not parallel-sided.
D. heteracantha White 1842
|Superior spines of each hind tibia shorter than width of tibia; tibiae themselves stout and parallel-sided.
D. fallai Salmon 1950
|11||With at least one apical spine on each hind femora.||— 12|
|Without any apical spines on any of the femora.
H. alterna Salmon 1950
|12||With one apical spine to each hind femur.||— 13|
|With two apical spines to each hind femur.||— 15|
|13||The single apical spine prolateral in position; abdominal terga normal. 14 The single apical spine retrolateral in position; abdominal terga abnormal, being strongly emarginate.
H. parva (Buller 1895)
|14||Each middle tibia with two superior apical spines; medium-sized species of more or less uniform colour.
H. tibiata Salmon 1950
|Each middle tibia with one superior retrolateral spine about one-third back from apex; large, heavy-bodied species conspicuously banded transversely in yellow and brown.
H. maori (Pictet and Saussure 1894)
|15||With also one retrolateral apical spine on each middle femora.||— 16|
|Without such spines on the middle femora; hind tibia flattened above, markedly rugose with the spines of each side very large and stout.
H. crassicrurus Salmon 1950
|16||The retrolateral apical spine of each middle femora extremely small; in female the ovipositor relatively short.
H. brevaculea Salmon 1950
The retrolateral apical spine of each middle femora larger, of normal size; ovipositor relatively much longer.
|17||Inferior spines of fore and middle tibiae long and slender; each middle tibia with a long superior retrolateral spine distal two-thirds.
H. broughi (Buller 1896)
|Inferior spines of fore and middle tibiae shorter; superior retrolateral spine of middle tibia generally absent; males often with greately enlarged head:—|
|(a) with strongly-marked transverse colour bands.
H. thoracica (White 1846)
|(b) Without such contrasting colour bands, more uniform in colour with ochreous pronotum and darker, brown-coloured head.
H. thoracica subsp. figurata Walker 1869
|18||Male with ninth abdominal tergite porrected; female with paired appendages on sternite of Abd. VI.||— 19|
|Male with ninth tergite emarginate; female without appendages on sternite of Abd. VI.
H. anomalus Salmon 1950
|19||Male with tergite of Abd. IX greatly porrected and emarginate; female with sternit of Abd. VI produced posteriorly into two simple lobes.
H. similis Ander 1938
|Male with tergite of Abd. IX either slightly porrected or produced into two long finger-like processes; female with narrow, elongated, bilobed process arising from sternite of Abd. VI.||— 20|
|20||Each mandible with a long horn-like structure arising near its middle dorsally.
H. monstrosus Salmon 1950
Mandibles normal, without any such structures.
H. furcifer Ander 1938
|21||With the spines of each fore and middle tibia and the apical spurs of each hind tibia very long and slender.
Z. subantarcticus Salmon 1950
The tibial spines and spurs shorter normal.
|22||Sounding organ present on sides of abdomen adjacent to hind femur.||— 23|
|Sounding organ absent; male subgenital plate concave between the styles; female subgenital plate triangular, about as broad at base as long.
Z. fiordensis Salmon 1950
|23||Spines of sounding organ plate-like in shape and situated on Abds. I-IV in male: I-II in female; male subgenital plate concave between styles; female subgenital plate triangular, longer than the breadth at base, with the apex sharply pointed but not produced.
Z. gracilis Salmon 1950
|Spines of sounding organ of normal shape, short and stout; male subgenital plate straight across between styles; female subgenital plate triangular, broader at base than long, with apex produced into a long thin point.
Z. maculifrons (Walker 1869)
Ander, K., 1939 — Vergleichend-Anatomische und Phylogenetische Studien uber die Ensifera. Opus Entom. Supp. II Lund, 1939, pp. 1-306 (Deinacridopsis, p. 292).
Salmon, J. T., 1950 — A Revision of the New Zealand Wetas, Anostostominae. Dom. Mus. Rec. Entom. I No. 8, pp. 121-177.