Stick insects (Phasmatodea)

Female [Tectarchus huttoni] from Rimutaka Range.

Predation by wasps and possums is a threat in some areas of the country.

The New Zealand stick insect fauna contains 21 valid species in eight genera, but much taxonomic work remains to be done. Recent fieldwork and data analyses have revealed the presence of undescribed species, particularly in the South Island. Furthermore, several described species are of dubious validity. Current taxonomic research includes a large amount of collecting throughout New Zealand and all major offshore islands. Generic and species boundaries are being determined using both morphological and molecular genetic characters.

New Zealand insects and other invertebrates offer ideal case studies for testing a wide variety of evolutionary scenarios and hypotheses. Molecular systematic methods are being used to determine species boundaries in taxonomically problematic invertebrate groups, study the impact of environmental change on species radiations, and determine the origins and evolution of the New Zealand terrestrial invertebrate biota.

About

Stick insects are a group of plant feeding insects characterised by a remarkable similarity to their host vegetation. Stick insects belong to the insect order Phasmatodea and are found throughout the world, being most common and diverse in the tropics. There are about 3,500 described species throughout the world and many undescribed species. Stick insects are related to other insect orders such as Orthoptera (grasshoppers, weta, and crickets), Mantophasmatodea (gladiators), and Embioptera (web spinners). The higher level taxonomy of stick insects and their relationships to other insects is currently being researched.

Stick insects feed on vegetation and are usually active after dark. They can be found on a variety of native plants in addition to some introduced plants common in gardens. When disturbed, stick insects will often fall to the ground and “play dead” for hours. Another bizarre behaviour is the “dance”, where the stick insect sways back and forwards for hours in a peculiar motion, the function of which is a mystery. Many stick insect species, including some New Zealand species, can reproduce without males, a mode of reproduction known as parthenogenesis. Stick insects are relatively common in New Zealand although introduced wasps, rats and possums are a threat in some areas.

New Zealand has ten genera of stick insect and 23 recognised species. However, this number is likely to change as taxonomic research progresses, and scientists are already aware of undescribed species from various localities. Because of the great taxonomic problems that stick insects present identifying New Zealand stick insects cannot yet be done reliably in many cases. However, the information on this web site and the paper by Jewell and Brock (2002) will allow identification to genus.

Collection

The Phasmatodea Collection at Landcare Research is part of the New Zealand Arthropod Collection and contains approximately 2000 specimens. Many of these specimens are preserved in 100% ethanol and stored at low temperature to enable molecular genetic studies as well as morphological analysis. Many older specimens are stored in 70% ethanol or pinned. The collection also includes eggs, which are very useful in stick insect taxonomy. The stick insect collection is currently being databased and these data will be fully web accessible when completed.

We have also established breeding cultures of some New Zealand stick insect species in order to study their natural history, development and perform breeding experiments.