Bob Gosford’s Bug of the Week: the Garden Praying Mantis

I’m just back from a few days in a hot & humid Darwin and came across this delightful little killer sitting on the top of my car one morning. She (and I’m assuming that it is a gravid female because of her swollen abdomen) hung around long enough for me to bang off a few snaps. After I’d finished I picked her up and placed her on a local tree branch, where she soon melted into the bright green foliage, waiting patiently for a passing fly or caterpillar to wander into her grasp.

The Garden Praying Mantis (more properly called a Mantid) share our gardens around Australia, usually hunting with its cryptic colouring and shapes in foliage for its diet of other insects. Away from our gardens it is found in open forests and rainforests.

Praying Mantids are members of the Order Mantodea, which has 8 families and more than 1,800 species worldwide. In Australia we have 3 families (Mantidae, 116 species, Amorphoscelidae, 45 species and the single-species family the Hymenopodidae) for a total of 162 species.

Females lay upwards of several hundred eggs into a readily-identifiable egg-case known as an ootheca, which in the wild can be found on plants or on the ground under stones and other debris.

In the course of digging around for information on the Garden Praying Mantis I came across some very interesting references to the very similar False Garden Mantid Pseudomantis albofimbriata, which has a very interesting female breeding behaviour, characterised as an extreme form of sexual cannibalism.

As this article in the Sydney Morning Herald a couple of years ago on research by Katherine Barry of  Macquarie University into the breeding behaviour of Pseudomantis albofimbriata reports:

There is no stopping the male praying mantids of Sydney. Even after their heads have been chewed off by their female partners, these hardy insects continue to have sex for up to eight hours.

…

By observing hand-reared mantids closely, Miss Barry has found that females benefit substantially from consuming their male partners, a job they complete after the lengthy mating has finished.

In one of the first studies able to demonstrate this effect, she found the cannibalistic females put on weight and produced more eggs using the extra energy they got from a single meal of male meat.

“Sexual cannibalism can boost the reproductive output of the females by up to 40 per cent,” Miss Barry said.

…

And while about 40 per cent of trysts are fatal, in about half of these cases the males manage to copulate while being cannibalised.