Uninformed Comment

Fig wasps

Posted in Food, Nature by uninformedcomment on May 23, 2009

One of the most curious stories in nature is about figs and wasps.  Others have written at greater length (and much better) than I intend to – this is simply a basic (and necessarily incomplete) introduction to one of the most bizarre natural phenomena I’ve ever heard of, and a testament to the wonders of evolution.

Firstly, what is a fig?  It is a small fruit, something not unlike a date in flavour, and noted for its laxative properties.  As a foodstuff, figs are not too popular in modern Western society, but at one time they were considered a luxury and a delicacy.  Like dates, they’re nearly always sold dried, since they don’t last very long in their fresh state.  The biggest producer of figs is Turkey, with other producers mainly in the Middle East, North Africa and southern Europe; the archaeological record suggests that figs are one of the first cultivated crops, before even wheat and other cereals.

Asking that same question again – what is a fig? – but this time answering from a horticultural perspective, they’re flowers.  Inside-out flowers, in fact, which can only be pollinated from the inside.  There’s nothing here for a passing bee to browse on, for example, since bees are simply too big to get inside through the tiny hole provided.  So how are these flowers pollinated?

The answer is: tiny wasps, called fig wasps.

Fig wasp

A fig wasp

In fact, figs are probably the only place you’ll find fig wasps.  For most male wasps, it’s the only place they can live – in fact, they spend their entire lives inside a single fig, having sex and trying to escape.  Once they escape, they die – they usually don’t even have wings.  The females, however, do have wings, which enable them to take one journey in their lives, from one fig to another (often on the same fig tree) carrying pollen.  Both males and females are entirely dependent on figs, and figs are entirely dependent on the wasps.

The problem with explaining any life cycle is: where do you start?  There’s no neat beginning nor end, so let’s pick up the story with one of those females during her brief and rare journey from fig to fig.  She’s in the prime of her life, flying adeptly despite the weight of fig pollen she’s carrying, and especially despite the weight of her unborn children – she’s pregnant.  The father of her children might well be one of her brothers – but we’ll come to that drama shortly.

Hers is no aimless wandering – she’s looking for a fig of the same species to have her children in.  It’s pretty unlikely she’ll manage it – for every female that finds another fig, thousands perish in the attempt – but ours is lucky, and after several hours finds the scent of a suitable fig and alights upon it.  Wearily, she seeks and finds the only entrance to the fig – a tiny hole whose only purpose is to let in fig wasps.  Even then, she must cut her way in using the sharp protusions on her head expressly provided by nature for the purpose.

It’s another difficult job, getting inside, and in the process she loses several legs and her wings, before at last crawling into the inner cavity of the fig and laying her eggs.  Once her eggs are deposited, she dies, too weak to escape even if she had the body parts.  Steadily, the fig eats her corpse, digesting the nutrients remaining in her body and turning them into, well, more fig.

After some time, the eggs hatch, and the tiny larvae start to feed and grow.  There’s only one thing here for them to feed upon: fig.  In fact, that’s all they can eat, and all they ever will.  And, with passing weeks, they develop distinctly male and female characteristics, the females with wings, and the males with tunnelling equipment.  The males start painstakingly drilling holes out of the fig.  And, inevitably, the males and females mate, impregnating the females.

Eventually, the males have created holes through which they, and the females, can crawl to freedom, the females picking up pollen on the way.  Outide the fig, the females take to the wing; the males simply die.  And once on the wing, the females spread out, still carrying pollen, and still pregnant, and search for another fig.  The life-cycle repeats itself.

So, if you ever eat figs, remember that you’re eating flowers that are pollinated by wasps.  Or rather, you probably are if they came from Europe; nearly all varieties of figs grown in the Americas are infertile, propagated by man and untouched by wasps.    Personally, given the choice, I’d opt for Turkish or Egyptian figs, quietly hoping that I can detect the delicate crunch of protein-filled baby wasps in each bite.

Fig rolls - made by wasps?

Fig rolls - made by wasps?

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