Although it may say Jessie is the author, today Tim Blackburn is writing the story, another keeper at Melbourne Museum's Live Exhibits Department.

Every year as spring sets in, the department finds itself nurturing hatchlings of various species through the early and especially fragile stages of their lives. A notable influx of Giant Green Mantids, Hierodula majuscula, has just occurred, with hundreds of nymphs now devouring the Live Exhibits “mantid nymph” diet of fruit flies and pinhead crickets. Praying mantids are voracious predators that generally feed on invertebrates smaller than themselves.

The Giant Green Mantis can be found along coastal areas and in rainforests of far north Queensland. It is one of the largest mantis species found in Australia, with females being so obstructively robust that, despite having wings, they are unable to fly.

The robust body form of the female giant rainforest mantid prevents it from flying. Photo: Tim Blackburn. Source: Museum Victoria.

The Giant Green Mantis has a number of peculiarities, common to all mantids, which serve to spark the fascination of many observers. Its triangular head which bears two large compound eyes in its upper corners somewhat uncannily resembles that of the culturally accepted depiction of an alien. Furthermore, many readers would be able to relate their experience of being convinced that a praying mantis has watched them for an extended period of eye contact. These critters possess in each eye what scientists call a “pseudo-pupil”, which is in fact not a pupil but an artefact of the convergence of numerous ommatidia (tiny eyes) in their compound eyes. This structure has the effect of facilitating the illusion that the mantis is looking directly at an observer, irrespective of sudden changes in position. The pseudo-pupil may serve as a deterrent to predators, which are given the impression that they are being watched.

The triangular head of the giant rainforest mantid contributes to its alien-like appearance. Note also the pseudo-pupils in each compound eye. Photo: Tim Blackburn. Source: Museum Victoria.

The pseudo-pupil of the left eye of the giant rainforest mantid is visible in this photograph which illustrates the illusion of the mantid ‘keeping watch’ on an observer. Photo: Tim Blackburn. Source: Museum Victoria.

Despite being formidable predators, praying mantids would serve as a nutritious meal for predators larger than themselves, such as some birds and reptiles, and have therefore adopted strategies to minimise the risk. Mantids are able to camouflage in their habitat by resembling the colouration and sometimes the texture of their host plant or surface. Mantids are also able to move in a breeze as though they are rustling leaves. Strategies such as camouflage and being responsive to air movements may also assist mantids in reducing the chances of their prey detecting them and thereby escaping.

The Giant Green Mantis nymphs that have recently begun their lives in Live Exhibits will soon have their sexes identified (will be “sexed”) so that they can potentially be organised, on maturation, into appropriate breeding pairs. Males of any mantis species have what appears to be an extra abdominal segment than do females of that species, so sexing is easily accomplished. Male Giant Green Manitids have what appears eight abdominal segments while females have only seven. Like all mantis species, the sexually immature individuals appear identical to their parents in every respect other than their smaller size and wingless bodies. They shed their exoskeletons periodically as they grow, and it is not until their final moult that they adopt their winged, fully grown form.