Bug of the month - Rainforest Mantid

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by Caitlin
Publish date
1 March 2012
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One of the largest insect species we keep here at Melbourne Museum is the Rainforest Mantid (Hierodula majuscula). At around 70mm in length, the adult Rainforest Mantid is not the longest mantid species in Australia, but it is certainly the most buff.

An adult female Rainforest Mantid on the hunt for prey An adult female Rainforest Mantid on the hunt for prey
Image: Alan Henderson
Source: Minibeast Wildlife
 

Its powerful raptorial forelegs are equipped with razor-sharp spines that allow the mantid to pin and immobilise live prey. A resident of north Queensland rainforests, the adult's solid green colour enables it to all but disappear amongst the foliage. A mantid on the hunt may remain perfectly still for hours, waiting for the right prey to present itself. Looming over its meal and appearing to "pray", the mantid finally strikes with lightning-fast accuracy and shows its true colours as another of nature's perfect predators.

The life of the Rainforest Mantid begins as one of up to 400 hatchlings from the ootheca – an egg case laid by the female 40-60 days prior. Often attached to the underside of a branch or leaf, the hatchlings emerge downwards and crawl over one another to clear the way. The nymphs must disperse from their brothers and sisters, as once they start eating, any prey small enough is fair game - including each other! At this stage, H. majuscula nymphs are less than 10mm long. As the nymph moults and grows, it may vary from greens to browns and reds, but is invariably green by its final moult.

Mantid nymphs hatching and moulting Mantid nymphs hatching and moulting for the first time after emerging from the ootheca.
Image: Alan Henderson
Source: Minibeast Wildlife
 

A superb hunter, the Rainforest Mantid's best weapon is its vision. Its large, compound eyes boast a wide field of vision, enhanced by its head's extraordinary range of movement. As a result, the Rainforest Mantid hunts primarily during daylight hours.

Mantid with large eyes Large eyes dominate the Rainforest Mantid's triangular, highly mobile head.
Image: Alan Henderson
Source: Minibeast Wildlife

An adult mantid is able to prey on not only a large selection of insects, but may also attack small lizards and frogs. After securing the prey with its raptorial forelegs, the mantid devours it alive. These mantids often eat the nuisance parts first, such as an insect's powerful kicking legs.

Mantid eating a cockroach Insect prey is usually consumed head-first to reduce the chances of it getting away.
Image: Alan Henderson
Source: Minibeast Wildlife

The Rainforest Mantid lives a solitary life and may never come into contact with another of its species after hatching until it is time to breed. Only the mature male of this species is capable of flight, so it is left to him to navigate the precarious expanse of tropical rainforest to find the perfect a female who is ready to mate. In contrast to hunting, night seems to be the preferred time for mating (though it may begin during or continue into daylight hours). As a flying male is quite vulnerable, it is thought that breeding takes place in the dark to reduce the risk of aerial predators.

However, there is still one major group of insect predators active at this time – the microbats. To combat this, many mantid species including H. majuscula have evolved a single ear on the lower side of the thorax, capable of picking up the ultrasonic sound frequencies of the microbats' echolocation signals. If the male mantid in flight detects such a signal, he immediately dives and weaves in such a display of evasive manoeuvres that he has been compared to a fighter jet.

In the dark, mantid eyes are much less effective. To counter this, a female of the breeding inclination sends out pheromones to attract suitable males. Once the male locates a female, he tempers his approach until the correct moment. He may wait hours within thirty centimetres of her, before rushing her in a mad frenzy and attaching himself to her back with his forelegs. If he is lucky, he will have attached himself a way that prevents her turning around to eat him. If he is unlucky, he may immediately become a meal. Either way, the Rainforest Mantid male can continue to mate even with his head completely missing. It's not all bad news for the male's genes: by becoming an extra meal, he may give his offspring a greater chance of survival by nourishing the female through the month of egg incubation.

Mantids mating This male is one of the unlucky individuals that has not survived the mating process.
Image: Alan Henderson
Source: Minibeast Wildlife
 

Rainforest Mantid females may live for up to a year. Though males may be capable of living just as long, their risky lifestyle results in a lower average life span. However, if a male survives mating, he may go on to mate with many more females and live to a ripe old age.

Comments (3)

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Deanna 4 March, 2012 10:57
Fantastic blog - I love praying mantids! They are one of the coolest bugs. They're always watching you!
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Luke 6 March, 2012 09:07
Remarkable animals. Love the bungee-jumping nymphs emerging from the egg case. Nice images.
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Simon 1 February, 2013 11:57
I love those mantids, they have very bright colours! :)
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