CanterburyNature

Orthodera novaezealandiae

Written by Lukas Adam (Lincoln University)

July 2005

Edited by Michael Hudson, Lincoln University, September 2006

Taxonomy

• Scientific name: Orthodera novaezealandiae (Colenso, distinguished from Orthodera ministralis by Beier, Caudell, Giglio-Tos, Kirby and Westwood)
• Popular Common names: Praying mantis
• Other common names: Common praying mantis, common mantis, whē, rō, wairaka

• Kingdom: Animalia
• Phylum: Arthropoda
• Class: Insecta (the birds)
• Order: Dictyoptera (the cockroaches, termites, and mantids) (previously Mantodea)
• Family: Mantidae (the mantids)

• New Zealand Status: native (endemic)

• Taxonomy sources: Lessiter (1990), Parkinson (2001), Ramsay (1990).

Identification

Species Description

The interesting shape of mantids makes them easy to recognise. Often found in gardens the mantids are much admired, especially by children (personal observation). The New Zealand praying mantis is a large bright green insect with an adult body length of approximately 40 mm (Parkinson, 2001) (Figure 1). It has a small triangular head with large compound eyes and also a smaller pair of less obvious eyes. The head is moved about and rotated by a flexible neck and thorax. Forelegs are long and powerful; lined with sharp spines for catching prey. A purple spot can be seen on the inside of the femur (mid section) of the foreleg. As well as being part of the mantis’ ear (tympanic organ), it may also be used as part of a defensive stance (Miller, 1984). The mid and hind legs of the mantis are long and thin. Two pairs of wings, which mostly remain safely tucked away on top of the abdomen, are attached just below the thorax: the front pair thick for protection, the hind pair larger and gauzy (Child, 1974). The female mantis is noticeably larger; especially when laden with eggs (Grant, 1999).

Comment: The New Zealand praying mantis (Orthodera novaezealandiae) was distinguished from its Australian counterpart O. ministralis by various entomologists soon after it was first described by Colenso in 1882; but has only become fully recognised as a New Zealand endemic species over the past few decades.

Similar species

A few features distinguish O. novaezealandiae from a South African species of praying mantis (Miomatis caffra), which has relatively recently established in New Zealand. The ‘Spring bok’ mantis (M. caffra) males are very slim compared to the females with a very swollen abdomen. Both male and female have a ‘pinched’ thorax (Miller, 1984) (Figure 2). Ramsay (1990) includes an excellent diagram comparing male and female O. novaezealandiae with the male and female M. caffra.

Geographic Distribution

Full natural and naturalised range

O. novaezealandiae occurs only in New Zealand.

New Zealand range

The New Zealand praying mantis was until recently widespread throughout the country. At the time of publishing Ramsay (1990) discusses the displacement of the NZ mantis occurring in the northern part of the North Island by the Spring bok mantis. The only part of mainland New Zealand where O. novaezealandiae is naturally not present is the West Coast of the South Island. Also they only occur on some offshore islands; not Stewart Island or the Chatham Islands (Ramsay, 1990).

Canterbury range

Because the New Zealand mantis has adapted well to environments greatly modified by humans, it is commonly found throughout the fields of the Canterbury lowlands, in the gardens of Christchurch and on Bank’s Peninsula (Ramsay, 1990).

Natural History in Canterbury

Habitats

The natural habitat of the praying mantis is in the more open country. Here the praying mantis can perch on the outer leaves of plants and wait for prey to pass. Perhaps the NZ praying mantis may not have been as abundant in pre-settlement times as the vast majority of New Zealand was densely forested (Ramsay, 1990).

Preferred habitats

O. novaezealandiae prefers shrub land and open country rather than forest or grassland. The praying mantis uses the outer leaves of plants exposed to the Sun; here it is camouflaged. As previously suggested the population of praying mantis may not have been as extensive before parts of New Zealand were cleared by Maori and European settlers. There is evidence to suggest a population increase during the 1870s and 80s (Ramsay, 1990).

The modern day habitat of the NZ praying mantis includes gardens full of non-native plants; meaning that the mantis is somewhat adaptable to new environments (personal observation). Female praying mantis attach their egg cases to the surface of solid objects e.g. a branch, post or wall in the landscape. For this reason habitats altered and built upon by people are often suitable (Sharell, 1982).

Phenology/Breeding

The mating season for O. novaezealandiae starts in mid March and lasts for about three weeks (Sharell, 1982). Contrary to mantids in other parts of the world, the female of the New Zealand species rarely perform the gruesome after mating ritual of attacking and consuming her partner. Mating may last several hours. After this time the male is commonly found dead. After completing the most important role in the mantis life cycle the male usually dies of exhaustion (Sharell, 1982).

In autumn, after the eggs have been fertilised, the female’s appetite grows and as her abdomen swells she seems to move about with some difficultly. The ootheca (egg case) is pushed out of the rear end of her abdomen as a foamy sparkling mass, but soon hardens upon prolonged exposure to the air. This process of exuding the egg case is guided by a pair of cerci (sensory appendages), and the “zipper-like” (Parkinson, 2001) form is achieved by a slight back & forth and up & down pulsation of the abdomen. To complete the intricate procedure the female then uses her ovipositor to insert 20 to 25 eggs into the egg case. Each egg occupies an individual chamber with a covering membrane (Sharell, 1982). The clever design of this ootheca will mean that the developing larvae will be protected against water infiltration as well as both the cold and the heat (Sharell, 1982). Although the female may move on to mate and lay several other egg cases in autumn, only one generation is produced each year. Like most insects, praying Mantids are r-selected, meaning that they have a large population size, relatively short lifespan, and small body size, resulting in rapid rates of reproduction (Miller, 1984).

Life cycle

Life starts for the praying mantis usually in the early morning in spring when nymphs (a juvenile praying mantis) struggle their way out of their egg cases. Once out in the air they quickly gain their green colour and begin to actively discover their surroundings; initially still weak and unstable until their tiny legs strengthen (Miller, 1984). At this stage they already closely represent their adult form, although they are far smaller and yet to develop wings. Because the nymphs are still too small to catch larger prey, they start out by feeding on smaller flies and aphids, and occasionally each other. Those cannibalistic acts are most likely due to mistaking other mantids as prey (Sharell, 1982).

Over the summer months the young praying mantis will shed their skin around five times. Wing development occurs after the fourth moult (Sharell, 1982). Fully grown by late summer the praying mantis are ready to complete the life cycle by finding a mate. Each mantis lives for about 7 to 8 months. The male usually dies after mating one or several times. Similarly the female will die after laying her eggs, perhaps on more than one occasion (Sharell, 1982).

Diet

Praying mantis are completely carnivorous; they are not selective eaters – they will eat virtually any insect small enough to be caught by their powerful and speedy lunge (Ramsay, 1990). While nymphs will stalk smaller insects, adults will eat flies, wasps, cockroaches, butterflies, cicadas, crickets, moths and even the occasional spider. One adult mantis can eat up to 25 flies per day (Miller, 1984, Crowe, 2002).

Behaviour

Because of the strategy used by the mantis for catching prey, they are usually found alone on the outer foliage of shrubs, waiting for another insect to pass within range of its leap. Although the O. novaezealandiae does possess two pairs of wings, it rarely flies more than a short distance. On the other hand a praying mantis is capable of running very quickly when provoked (Parkinson, 2001; Grant, 1999; Walker, 2002). Among the majority of mantis species a defensive position is commonly adopted whereby the forelegs are raised and sustained above the body. The same posture is uncommon in the New Zealand praying mantis. It is however argued by some that the spots on the femur only gain a blue colour for this defensive stance (Sharell, 1982).

One of the more interesting parts of praying mantis behavioural patterns is the method by which they catch and eat their prey. The mantis uses green camouflage to blend into the foliage. Here it sits allowing its body to be swayed back and forth by the wind. Raptorial forelegs (adapted for seizing prey) are held tightly against its chest, in the characteristic ‘praying’ stance, as the mantis waits for an insect to walk or fly by (Miller, 1984, Parkinson, 2001, Walker, 2002). When the moment comes, the mantis lunges out, throwing its long powerful forelegs out at the prey. The complete movement can take as little as one twentieth of a second and result is the prey item being held in the mantis’ vice-like grip, ready to be devoured (Walker, 2002, Crowe, 2002, Miller, 1984). Typically the insect will be eaten piece by piece with the legs, wings and some other parts often being discarded. Once the mantis has finished the meal it will use its jaws to methodically clean its forelegs. The praying manits then moves on to concentrate on trapping its next victim, forelegs held against its thorax (Sharell, 1982, Grant, 1999, Miller, 1984).

Predators

Predation of the adult mantis is mainly by insectivorous birds and lizards, with cats (Felis catus) and long-tailed bats (Chalinolobus tuberculatus) possibly also playing a predatory role (Ramsay, 1990). The mantis will rarely adopt a defensive position usually attempting to run or fly away. Damage to the oothecae suggests that insects including butterflies, moths and beetles may attack the egg cases (Ramsay, 1990).

Competitors

The greatest competitor of the is the Spring bok mantis. This naturalised species has begun to incrementally colonise further into the territory of the O. novaezealandiae. The Spring bok mantis displays many similar characteristics and is becoming the more prevalent species in northern areas of the country. Successful establishment is a result of the nymphs having a greater rate of survival. As a result the period of hatching does not have to adhere to such strict seasonality as the NZ praying mantis. Another reason for the increasing dominance of the M. caffra is the greater number of hatchlings per ootheca (Ramsay, 1990).

Parasites

The oothecae of the O. novaezealandiae are commonly parasitized by several species of wasp (including Eupelmus antipoda). The wasp eggs are laid into the mantis egg case, the resultant wasp larvae will eat the mantis larvae before emerging in the place of mantis nymphs in spring (Sharell, 1982).

How to find the Praying mantis

Adult praying mantis are usually found in the sunniest parts of the garden, perched in the outer foliage of low bushes. They also inhabit shrubbery in the fields (Sharell, 1982). Egg cases can be found on branches, posts and fences from late autumn to spring. The nymphs can be observed as they energetically move around bushes (Walker, 2002).

Abundance and Conservation Status

• New Zealand: abundant
• Canterbury: abundant

Although the New Zealand praying mantis is abundant throughout most of the country, it faces a major threat from the Spring bok mantis. The South African species was accidentally brought into the country and was first seen in Auckland gardens in the 1970s. Since then it has replaced the New Zealand species with its gradually spread north as far as Kaitaia and south as far as Paeroa (Ramsay, 1990). Because of the ability of the Spring bok mantis to withstand harsher weather conditions as a nymph, it appears that M. caffra will continue to extend its territory as time goes by. The New Zealand mantis is not under threat from human alteration of the landscape. Having adapted well to the changes made the NZ mantis has in fact probably benefited from the clearing of native bush.

Significance for people

Traditional Maori significance and uses

According to Maori legend if a whē (stick insect or mantis) sat on a woman it was an indication of conception. According to the species of whē, it could be said if the child would be male or female (Ramsay, 1990).

Modern Uses

The praying mantis is a popular species among insect watchers because of its interesting behaviour. It is easily found on the leaves of plants in the garden and remains relatively motionless while hunting prey (Sharell, 1982).

Summary

The endemic New Zealand praying mantis is an interesting creature; one which has fascinating behaviours that intrigue many people. Its alien-like body and gruesome habits make it extremely appealing to study. It is currently wide spread through out most of the country, but faces the threat of at least local extinction in many areas because of the competition from the Spring bok praying mantis. If nothing is done to protect our native praying mantis, within a few decades we may no longer be able to observe its intriguing way of life in our gardens.

References

Bowie, M.K. & Bowie, M.H. (2003). Where does the New Zealand praying mantis, Orthodera novaezealandiae deposit its ootheca? The New Zealand Entomologist, 26, 3-5.

Castle, J.F. (1988). Behaviour of the mantid Orthodera ministralis. The Weta, 11(2), 25-29.

Child, J. (1974). New Zealand insects. Universities Press, Hong Kong.

Crowe, A. (2002). Which New Zealand insect? Auckland, New Zealand: Penguin Books Ltd.

Grant, E.A. (1999). An illustrated guide to some New Zealand insect families. Manaaki Whenua Press, Lincoln, New Zealand.

Miller, D. (1970). Nature in New Zealand: Native insects. Dai Nippon Printing Co., Hong Kong.

Miller, D. (1984). Common insects in New Zealand. Dai Nippon Printing Co., Hong Kong.

Lessiter, M. (1990). Interesting insects. The Bush Press, Auckland, New Zealand.

Parkinson, B. (2001). Common insects of New Zealand. Reed Publishing (NZ) Ltd., Auckland, New Zealand.

Ramsay, G.W. (1990). Mantodea (Insecta), with a review of aspects of functional morphology and biology. Fauna of New Zealand 19, Landcare Research, New Zealand.

Sharell, R. (1982). New Zealand insects and their story. Dai Nippon Printing Co., Hong Kong.

Walker, A. (2000). The Reed handbook of common New Zealand Insects. Reed Publishing (NZ) Ltd., Auckland, New Zealand.

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