Sunday, June 9, 2013

Let Us Prey: Looking a Mantid in the Eye

It is devout, a diviner, a caring mother. It is abominable, a killing machine, a cannibal. From ancient times until today, the praying mantis has carried much human baggage, both praise and prejudice.

The ‘praying’ description comes from the raised and folded position of its two front legs at leisure, though some people have suggested that ‘preying’ is a more appropriate word. The other part of the name is from a Greek word meaning ‘prophet’: the ancient Greeks are among various groups who have attributed supernatural abilities to the mantis.

I have my doubts that it has super-powers. They
re a lot to expect of something you could kill by stepping on it accidentally. But “mantids tend to attract more than their fair share of public interest and enthusiasm”, New Zealand entomologist Graeme Ramsay observed. Perhaps his 1990 study bears this out: it comes to about 100 pages, the length of nearly 500 adult mantids placed end to end. 

My own interest was piqued by an article in the Forest and Bird magazine. It prompted me to look closely at praying mantises in my own garden, and to go further afield to learn more.

The mantis and the migrant

The world has up to 2000 species of mantises, I discovered, and these insects make themselves at home in many countries. Not the UK, however. On returning here in 1947 as a young teenager, Fleur Adcock was intrigued to see her first praying mantis. More than 60 years later, she’s given it life again in a poem about the unfamiliar new world facing a migrant:

The new collection in which this features, Glass Wings, has a dragonfly on the cover, and also includes poems on bees, beetles, stick insects... Adcock is keen on all of them. One of her most anthologised works, ‘For a Five-Year-Old’ (a favourite of mine, too), has a wise and wily conclusion about kindness to snails.

Not all New Zealand settlers have been as kindly disposed as Adcock is to the praying mantis. The Otago Witness columnist
Entomologist claimed in 1890, “There is no insect more rapacious and more quarrelsome and bloodthirsty than the mantis.” 

The writer labelled it “abominable”, presumably on account of its tendency to eat its prey alive, a process he (?) described twice and in detail. He grudgingly admitted, however, that its predation of some pests meant it was likely to do more good than harm to crops.

What the best-dressed insect is wearing

Another commentator, Eleanor Brown, enthused about mantids in the manner of an early 1900s society columnist describing what the best-dressed people are wearing. “When mature, their outer wings are so like a stiff green leaf, that one can hardly help mistaking them for one; but hidden beneath those stiff ones are a daintier pair (only unfurled for flying) in diaphonous folds of tender green, and radiating tints of pearly grey, set off by the stronger contrast of bright orange and peacock-blue of the spots on the fore-legs.” 

Eleanor Brown illustration, New
Zealand Illustrated Magazine
, 1904.
Such glorious raiment was not Miss Brown’s only focus. She noted that “The maternal solicitude of the mantis guides her to choose and fix upon some well-favoured leaf or branch to attach her frothy egg-cabin to; she so effectually renders it a dwelling of safety for her brood, that I’m sure a bird would scorn to touch such an unsavoury-looking structure.”

Living larders
A bird might not be tempted, but for some tiny parasites, the oothecae (egg cases) and their contents are “weatherproofed living larders”, according to biologist John Walsby. In New Zealand, these parasites are “mostly the larvae of very small wasps, such as Eupelmus antipoda”. The NatureWatch website shows one of the latter on a New Zealand mantis ootheca, ready to lay its own eggs there.

Nor are wasps the only threat to the New Zealand mantis, Orthodera novaezealandiae. Other mantids have sometimes been intercepted entering New Zealand as stowaways, but the South African mantis Miomantis caffra made it through, undetected until 1978 when a schoolboy in New Lynn, Auckland, found some of its nymphs (juveniles). By then the exotic species was already established here, and now it may be overtaking ‘our’ mantis. Of the four mantids I’ve found in my garden since March, three were M. caffra.

Young South African mantis 
(also featured in top photo).

The recent arrival’s winning ways
In a passionate piece of advocacy for the local mantis, conservationist Graeme Hill reported that the New Zealand male can’t tell the females of the two mantis species apart: “He will attempt to mate with the South African but in doing so either wastes his issue... [or] his romantic forays will stop right there due to an infamous habit of the female Miomantis caffra – cannibalism. He gets eaten in flagrante delicto for his mistake. The New Zealand female does not cannibalise her suitor.” Well, never say never... but others contend that it’s rare.

Miomantus caffra female,
very pregnant.
The South African lays many more eggs per ootheca (perhaps that’s why she tucks into a massive post-coital meal). Another advantage for her species is its tendency to shelter under leaves or in long grass, while the local mantis sits on the top of leaves and becomes easy prey for larger predators.

It was Hill’s article in Forest and Bird that alerted me to the competing species. I soon followed his lead, trying to increase the chances of the native mantis in my own garden by eliminating the competition. It may seem mean – the more so given their comical and cute appearance – but I give them to my hens, who love to snack on insects. Death by chicken is usually very quick.

Spotting the difference
Unlike the New Zealand mantis male, I now know enough to distinguish between the two species:
- compared with the New Zealanders, the South Africans have much narrower bodies between the first two sets of legs;
- the New Zealanders are always green; the South Africans are sometimes beige or other shades;
- most distinctively, only the New Zealand mantis has a beautiful purply-blue spot on the inside of each front leg. (It’s not an ear, as some people think, though the mantis has an ‘auditory receptor’ on the underside of its thorax.)

New Zealand mantis in a hurry,
traces of cobweb still on its wings.
The one ‘local’ I’ve found this year was caught in a spider’s web in my front porch. When I came to the rescue, it was in such a hurry to leave that I couldn’t snap an ‘in focus’ photo. 

Still, I was able to spot the difference, and to release it under the broccoli plants, rather than deliver it to the killing machines in the chicken run. 

* * * * *

O. novaezealandiae its past and future
Mantids tend to inhabit tropical or subtropical countries, and New Zealand is the southern limit of their worldwide distribution.

Some theories date the arrival of our first mantis back only as far as early European settlement, suggesting it stowed away on materials imported by ship. What we now call the New Zealand praying mantis was once thought to belong to a species in Australia (which has more than 100 types of mantis), but is regarded
these days as distinct.

In 1990, leading authority George Ramsay concluded that the New Zealand mantis was established here “probably long before human settlement”. A century earlier, ‘Entomologist’ had described it as having “always been very abundant in the most northern portions of New Zealand, and [it] seems of later years to have become very prevalent in the Middle [South] Island.” John Walsby has summarised its present range as “from North Cape to Bluff, but [it] is absent from the high country and rare on the South Island’s wet West Coast”.

That sounds fine, until you read about the spread of the South African mantis. Ramsay wrote that it is gradually extending and consolidating its distribution in Auckland and the north. Miomantis caffra is adaptable, apparently, and better able to survive the Auckland winter than the long-time local mantis. 

“It may well eventually colonise a greater area of New Zealand than the latter species. Indeed, it may even be able to displace it, as in some areas it is now more frequently seen than O. novaezealandiae, which formerly was the more common.”

Mantid hygiene is a priority.
Bits of cobweb on this New
Zealand mantis give it even
more reason to wash.
 Related Reading
Fleur Adcock; Glass Wings; Victoria University Press; 2013; the poem ‘Praying Mantis’ is reproduced on this blog with the kind permission of VUP

Eleanor Brown; ‘A Study of Insect Life’; New Zealand Illustrated Magazine; Feb 1904; c/- 

Adam Dudding; 

Entomologist; ‘Entomology; Otago Witness; 18 Sept 1890; c/-

Graeme Hill; ‘Springbok Invasion’; Forest and Bird; Feb 2012 

Mantids’ in The New Encyclopedia of Insects and Their Allies; ed. Christopher O’Toole; OUP; 2002; c/- Oxford Reference Online
Ramsay, Graeme; Mantodea (Insecta), with a review of aspects of functional morphology and biology’; Fauna of New Zealand 19;

John Walsby; ‘On a Wing and a Prayer’; New Zealand Geographic; Issue 029, Jan–Mar 1996.