Stick insects belong to the insect order Phasmatodea – the name comes from the Greek word ‘phasm’, meaning phantom. The order includes about 3,000 species worldwide, with most diversity around the tropics. New Zealand’s temperate climate supports more than 20 described species of stick insect.
Stick insects look and behave like twigs or leaves to avoid being eaten. Also known as walking sticks, they come in a wide range of colours, textures and sizes, although they are all well disguised in their natural habitat. Their main predators are birds that hunt by sight. As a result of natural selection, and pressure from birds and other hunters, stick insects have evolved a suite of extraordinary features, structures and behaviours.
Behaviour and habitat
During the day most stick insects sit where they are least visible. Although some eat, they generally remain still, move very slowly, or sway like leaves in the wind. At dusk and at night they are more active, seeking out their preferred leaves to eat. Adults of the small spiny stick insect (genus Micrarchus) often move down to the base of the ribbonwood trees they feed on. They hide among the fallen twigs and leaves, while green nymphs of this species stay among the foliage.
New Zealand’s largest stick insect, Argosarchus horridus, often settles where there are fewest leaves but lots of twigs in the trees it feeds on. Females can be up to 20 centimetres long. Adults of the all-female variable stick insect (genus Acanthoxyla) lie along twigs where foliage is most dense. Species of the alpine genus Niveaphasma live among the tangled branches of Muehlenbeckia species.
Is naomi a freak?
In 1991 a new stick insect species (Asteliaphasma naomi) was found near Lake Waikaremoana. The single female specimen is held at the Museum of New Zealand Te Papa Tongarewa in Wellington. Further searches around the lake have only found another similar species (Asteliaphasma jucunda). Is the insect kept at Te Papa a strange variant of that species? Or do others of her kind live around Waikaremoana?
What they eat
Different stick insect species prefer particular plants. The bristly stick insect (Argosarchus horridus) eats ramarama and ribbonwood. Niveaphasma eat Muehlenbeckia. Stick insects of the genus Clitarchus eat kānuka and mānuka. Endemic stick insects (those unique to New Zealand) will eat a range of plants, either native (pōhutukawa, rātā) or not (blackberry, raspberry). Acanthoxyla stick insects eat a range of native plants, but are unusually fond of the exotic macrocarpa and cedar trees commonly found in urban areas.
There is scattered information on the status of and knowledge about stick insects in Māori tradition. Names include rō, whe and wairaka. In some traditions they were considered to be relatives of the mantis. If either of these landed on a woman it signified she was pregnant, and which insect it was indicated the child’s sex. Some sayings claim that gardens are unsuitable where there are stick insects. In other sayings, when they drop onto you from a forest tree it is a sign that you have entered a sacred site.
In legend, before creating people, the god Tāne Mahuta fathered (with Punga) the trees, birds and insects of the forest. It was Tāne who pushed apart the sky (Ranginui) and earth (Papatūānuku) so there was light, allowing the forest inhabitants to see, breath and move. The insects are considered to be the children or embodiment of Tāne and deserving of respect.
In the story of Rātā, who cut down a tree to build a canoe without first paying respect to Tāne, the insects gathered each chip of wood and leaf and returned them to their proper place so the tree was whole again.