Extatosoma tiaratum

The Extatosoma tiaratum is a species of stick insect native to the gum forests of Australia; they are herbivorous with Eucalyptus making up most if not all of their diet in the wild. In captivity this species has been known to eat bramble, raspberry, rose, hawthorn and oak leaves.

Terra, adult female Extatosoma tiaratum

Video: http://s759.photobucket.com/user/Ruyina/media/Stick%20insects/P1011...

Typically this species will be beige or mottled brown in appearance with an incredible array of leafy foliage adorning the creature like armour. These leaves have an impeccable level of detail to them including creases and holes to make them look as close to the genuine article (that is, dead, damaged and decaying leaves) as possible. From a distance the Extatosoma tiaratum should look like a dead and dry leaf that is beginning to curl. In terms of camouflage, God has also given all phasmids the fantastic ability to mimic a leaf swaying in the breeze; when confronted with a change in light or a breeze, a phasmid will start to sway from side to side; this swaying can become very dramatic and very, very comical. While it is indeed very funny it does serve a purpose: if these creatures can look like a dead leaf being blown about by a breeze they can better avoid predation.

Even though Extatosoma tiaratum have extensive and very effective camouflage, God has not left these stunning creatures defenceless in case a predator sees through the fake foliage. When threatened this species, regardless of gender, will stand on their front and middle legs with their back legs stuck up in the air, displaying sharp barbs; these barbs can be clamped together in a pincer movement and will easily draw blood on a human. Adults can also exude a substance from their mouth that smells like toffee, peanut butter or vinegar; while not entirely unpleasant for a human, for a predator with a keen sense of smell it can be very overpowering. Females will regularly curl their tail over their back in a scorpion pose to ward off predators, as well.

Unlike most phasmid species however, where the males are often brightly coloured and more noticeable, it is actually the female Extatosoma tiaratum that shows an elevated exuberance and uniqueness – in fact, if you did not know what you were looking for, you could quite easily mistake a male E. tiaratum for an entirely different species when compared to the females.

Female, Terra (right); Male, Firma (left)

The females can grow to a maximum length of around 20cm in the wild (15cm in captivity) and are big, bulky and covered in “armour” plating and spines; these spines protect the creature and give this species one of its two common names, the giant spiny leaf insect (although this species is not a true leaf insect). Once they reach adulthood the females sport a pair of adorable wing buds; in most cases an adult female will grow with her wing buds pressed tightly against her back but in some cases the buds will be raised ever-so-slightly and the undeveloped wings beneath can be clearly seen. Once they reach egg-laying age the female Extatosoma tiaratum can exceed 60 grams in weight and so she would simply be too heavy to fly if she had functional wings.

Female Extatosoma tiaratum usually live between 9 – 16 months in total, with over half of that time spent as an adult. Once they reach adulthood, females of this species will start to lay eggs after 2 to 4 weeks; she does not need a male to reproduce but any offspring produced without a male, through a process known as parthenogenesis (literally translating to “virgin birth”) will be genetically weaker and all-female (males cannot be produced this way as parthenogenesis is the cloning of the mother’s DNA).

Gaia, adult female 

The males on the other hand usually grow to an absolute maximum of 15cm long and are very slender and delicate in appearance; they need to be slender and light in weight as, once adults, they will need to fly to reach potential mates. Adult males have a pair of stunning fully-functional wings and the wingspan of these can easily exceed his maximum length. The males are more active than females due to their need to find a mate but once they have found that bride-to-be, the male will usually grip onto her and seldom let go except to feed.

Males live for a shorter period of time than females, usually between 6 – 12 months. Thankfully, once a male has mated a female, she will be able to store his sperm for several months so if her mate perishes due to old age she will continue to produce fertile eggs without needing to resort to parthenogenesis.

Creeper, sub-adult male

When it comes to laying eggs (or “ova”) the adult females are somewhat reckless in their approach; they lay an egg, holding it in a small cup at the end of their abdomen and then begin to sway from side to side quite dramatically, they then flick the egg as far away from their perch as they can; these eggs are extremely hardy and can easily survive a fall of dozens of feet. Despite how reckless this may seem it helps keep the females safe from predation as the eggs usually land far away from their mother.

The actual eggs look very similar to seeds and are usually less than a centimetre in diameter upon first laying, they are round with a sugar-cap on the end; this sugar cap is irresistible to the local ant colonies who pick the egg up, probably thinking it’s a seed, take it back to the nest, eat the cap and dump the egg somewhere dark, warm, humid and safe from predators. The eggs then incubate in peace taking 4 – 24 months for eggs laid by a mated pair and 9 – 24 months for eggs laid via parthenogenesis.

Terra's first egg 

After incubation, the newly hatched nymphs (baby insects) emerge as ant-mimics; they feature a red head, white collar and black body and this camouflage enables them to freely leave the ant colony without any issues. Extatosoma tiaratum nymphs are notoriously fast and are often said to “run around like headless chickens”, indeed they do, they scoot out of the ant nest and up the nearest gum tree where they head butt around looking for a leaf to chew.

A week old nymph 

After the first week or so of life the Extatosoma tiaratum nymph will undergo its first moult. Moulting is the shedding of the creature’s exoskeleton and is a dramatic, exhausting process; the nymph perches upside-down and waits for a split to appear along its back, it then – while its old skin is still attached to the perch – pulls itself out of the old carapace surprisingly larger than it was before. The change in growth is usually between 20 and 50%; the nymph will then eat its old skin as it is full of valuable proteins which can be difficult to acquire on a diet of leaves. Female Extatosoma tiaratum will moult approximately 6 times in their lifetime whereas males will moult only 5; the length of time between moults depends upon temperature. If the creatures are kept cooler they tend to live a little longer whereas if kept warmer their lifespan is shortened. 

Mother and daughter; adult female Extatosoma tiaratum compared to one approximately a month old

On one final note... when you have an adult female whose wing buds don't settle correctly, they look a little similar to the tooth fairies from the second Hellboy movie...

Maybe that's just me... but it's cute either way.

Can you spot the three nymphs in this photograph? The oldest (centre, I believe) is now this:

Isn't God amazing?!