Weta - General Characteristics

General Characteristics

Many weta are large by insect standards and some species are among the largest and heaviest in the world able to fly. Their physical appearance is like a katydid, long-horned grasshopper, or cricket, but the hind legs are enlarged and usually very spiny. Many are wingless. Because they can cope with variations in temperature, weta are found in a variety of environments, including alpine, forests, grasslands, caves, shrub lands and urban gardens. They are nocturnal, and all New Zealand species are flightless. Different species have different diets. Most weta are predators or omnivores preying on other invertebrates, but the tree and giant weta eat mostly lichens, leaves, flowers, seed-heads and fruit.

Weta can bite with powerful mandibles. Tree weta bites are painful but not particularly common. Weta can inflict painful scratches, with the potential of infection, but their defence displays consist of looking large and spiky, and they will retreat if given a chance. Tree weta arc their hind legs into the air in warning to foes, and then strike downwards, so the spines could scratch the eyes of a predator. Pegs or ridges at the base of the abdomen are struck by a patch of fine pegs at the base (inner surface) of the legs and this action makes a distinctive sound. These actions are also used in defence of a gallery by competing males. The female weta looks as if she has a stinger, but it is an ovipositor, which enables her to lay eggs inside rotting wood or soil. Some species of Hemiandrus have very short ovipositors, related perhaps to their burrowing into soil and laying their eggs in a special chamber at the end of the burrow.

New Zealand had no land mammals (apart from native bats) before humans arrived, and ecological niches occupied by mammals in other parts of the world were taken by nonmammals. The weta’s place in the ecosystem is comparable to that held by mice and other rodents elsewhere in the world. For example, they are hunted by an owl, the morepork, New Zealand’s only surviving native owl. Weta pass seeds of some plant species through their digestive tracts unharmed, thus acting as effective seed dispersers. The effects of decreases in weta populations on native plant species that may rely on the weta's help are yet to be determined. The weta's lifestyle and habitat, where it may choose to remain concealed in suburban environments until unexpectedly confronted, combined with its notoriously unfriendly appearance, make it a frequent victim of irrational human aggression.