Spiny Leaf Stick Insect Fact File
Credit: Public Domain
Wild 1 year
Captive 2 years
Spiny leaf stick insects are native to Australia and may be known by a range of other names including the Australian walking stick or Macleay's spectre.
These animals are strict herbivores which will only feed on leaves such as those of the eucalyptus tree, rose or bramble.
Females are capable of parthenogenic reproduction. This means that they can lay eggs which will hatch young without having mated with a male. Each female may produce up to 1,000 eggs.
The spiny leaf stick insect is a popular pet in Australia and is present in zoos around the globe. Despite this they face threats in the wild from wildfires and the introduction of ants.
Read on to learn more about these incredibly invertebrates.
What does the spiny leaf stick insect look like?
The spiny leaf stick insect is generally a tan colour across their whole body. Diet and environmental factors can lead to them appearing green, red, brown, white or yellow.
A form known as the lichen morph is recorded which resembles a patch of lichen.
They exhibit pronounced sexual dimorphism. The females have a thick body which is longer than the male who is quite slender. Females have small wings while those of males are quite large.
Covering most of their body are a series of spikes. On the male the abdomen is smooth while that of the female is spiky.
There is so much variation between the male and female that they were originally listed as two separate species.
Females average a weight of 25g (0.9oz) with one specimen reaching 32g (1.12oz). Males may be just half this weight. Females may grow to 20cm (8in) long while an average male is 10cm (3.93in) long.
What does the spiny leaf stick insect eat?
Spiny leaf stick insects are herbivores. Their preferred browse item is eucalyptus. They also feed upon guava, tree Lucerne, wattle, oak, rose, raspberry, hawthorn, salmon berry and bramble.
The different leaves they consume can impact upon their color and how large they will grow.
Credit: Cale Russell for The Animal Facts
Where can you find the spiny leaf stick insect?
Australia is the native home of the spiny leaf stick insect. Here they are found in the states of Queensland and New South Wales along the coast.
Introduced populations are occasionally reported in other states primarily from escapes from the captive population.
What kind of environment does the spiny leaf stick insect live in?
They live amongst the vegetation in tropical rainforest, temperate forests and grasslands. Most populations live in lowland areas while a lichen form is recognized primarily from higher elevations.
Populations have been recorded from urban gardens.
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How does the spiny leaf stick insect produce its young?
Spiny leaf stick insects can breed through sexual reproduction and by parthenogenesis, a process where the females fertilize their own eggs. Eggs which are sexually produced will hatch quicker than those birthed through parthenogenesis. Eggs hatched parthenogenically will also produce only females.
It is possible for between 500 and 1000 eggs to be laid by one female.
On the end of the eggs is a small knob known as the capitulum. This is considered edible by redheaded black ants. They will carry the eggs back to their burrow where they eat the capitulum and then they leave the eggs in the burrow. This protects them from predators. Eggs are colored brown and cream.
Upon hatching the spiny leaf stick insect resembles a redheaded black ant (as seen in the image below) more than a stick insect. It allows them to leave their burrow with the ants in safety until they find a nice tree in which to take up residence.
As they grow they moult their skin to allow their body to expand in size. It will take 6 months for them to reach full size. During this time, they will moult 6 times. They often eat their shed skin.
Should they lose a leg this is regrown during the moulting process.
What does the spiny leaf stick insect do with its day?
To avoid detection by predators the spiny leaf stick insect will blend in with their environment and sway like a leaf. If detected they will curl their tail back over their body so they look like a scorpion.
They will sway from side to side with the wind to help maintain their camouflage.
As young insects, they are quite active. As they grow they begin to spend more of their time being still.
Credit: Cale Russell for The Animal Facts
Predators and Threats
What is impacting the survival of the spiny leaf stick insect?
Natural predators of the spiny leaf stick insect include birds.
An estimate of their population in the wild has not been made. The species is a popular pet across Australia and has a large captive population.
Worldwide populations of this species are large but most of these are the result of captive breeding with little need to remove them from the wild to support this trade.
Some small threats to the species are recognized including wildfires which are increasing in frequency across their range and the introduction of invasive ants which prey on them.
When disturbed the spiny leaf stick insect emits an odor which smells like peanut butter, vinegar and toffee. This is used to deter predators.
They are a commonly kept species around the world.
This species is also known as the prickly stick insect, Australian walking stick or Macleay's spectre.
Credit: Pavel Kirillov from St.Petersburg, Russia, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons
Rudolf, E. & Brock, P. 2017. Extatosoma tiaratum. The IUCN Red List of Threatened Species 2017: e.T80201037A104413678. https://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T80201037A104413678.en. Downloaded on 24 October 2021.
Oregon Zoo. 2021. Australian walking stick. [online] Available at: <https://www.oregonzoo.org/discover/animals/australian-walking-stick-0> [Accessed 24 October 2021].