The bizarre world of the North American dance fly... | Exclusive extract from Nature Table book... And watch host Sue Perkins enter a duck's vagina

The bizarre world of the North American dance fly...

Exclusive extract from Nature Table book... And watch host Sue Perkins enter a duck's vagina

Hosted by Sue Perkins, Radio 4’s ‘show and tell’ comedy series Nature Table, celebrating the natural world, is currently airing its fourth series, featuring a roster of guest comedians including Bridget Christie, Dave Gorman, Jessica Fostekew, Desiree Burch, Zoe Lyons and Lucy Porter.

The first episode – currently BBC Radio 4’s Comedy of the Week podcast – covered a meteorite that offers a key to how life on Earth started and mallard ducks’ anti-corkscrew vaginas. And here’s an exclusive clip of expert Jules Howard offering Perkins a trip inside a duck’s vagina via a VR headset, recorded at the Natural History Museum:

The series is also accompanied by a book of amazing and funny facts from the natural world entitled A Housefly Buzzes In The Key Of F, written and compiled by the show’s co-creator and producer Simon Nicholls. Here’s an exclusive extract from the book, about the curious dating techniques of North American dance flies...

North American dance flies are very tiny flies – only about 1cm long. When it comes to attracting a mate, these females are properly magnificent wonder women.  Dance flies are so-called because of their bobbing flight movements, which they do to grab the attention of potential mates in the swarm. Not to be confused with Dancing On Ice flies™, who wear sequinned jumpsuits, ice skates and love nothing more than moving to Maurice Ravel’s Boléro. 

Dance flies are also sometimes known as ‘balloon flies’. This is because of their ‘nuptial gifts’ (a present that encourages a potential partner to become a definite partner). As leading entomologist Dr Karim Vahed informed us, the genius of female dance flies begins with these nuptial gifts... 

Dance Fly
Photo:James Lindsey Ecology of Commanster, CC BY-SA 3.0

Female dance flies never hunt for food 

Female dance flies have no need to hunt for food, they’re too clever for that! Instead, females force the males to bring them nuptial food gifts before they mate. Until the male offers the female a food gift, sex is off the table. Them’s the breaks. 

So, males are in the habit of catching an insect and feeding it to the female during copulation. All very romantic and recognisable to many couples across the species. 

But a female dance fly’s wonder woman skills go way beyond getting a free meal...

It turns out male dance flies prefer bigger, better-fed females to mate with. This is because larger females have more eggs and a greater scope for more offspring. As a result, smaller female dance flies have a wily ingenious trick for securing both a partner and free meal... 

During courtship, smaller female dance flies trick males into thinking they’re bigger than they really are to secure sex and a  free food gift. The smaller females do this by having inflatable abdominal sacks, which they pump up before entering the mating swarm. By pumping up these sacks, a female fools the male into thinking she’s bigger than she actually is. The old inflatable costume ploy. 

Not only does the female wear her abdominal inflatable pants (available in all good chemists), but she also uses her extra-hairy legs to trick the male. 
The wonder woman dance fly holds her super-hairy legs down the sides of her body to make her look even bigger. The male dance fly, duped by the inflatable pants and sizeable hairy legs, offers a food gift and mates with a female that appears to be large and fecund, but isn’t. After copulation, the female deflates herself and the scam is complete! 
Two can play that game 

There’s no denying that female dance flies are bona fide wonder women. However, when it comes to fooling the opposite sex, it’s not all one-way traffic. As Karim went on to explain, male dance flies are cads... 

Male dance flies always wrap the female’s ‘nuptial food gift’ (often a dead fly). They wrap the gift by secreting silk from glands in their front legs. Silk wrapping paper, you say? Fancy! 

But not everything is as it seems. Sometimes, a rascal male dance fly gift-wraps a flower petal or small piece of wood instead of a juicy dead fly.

By the time the female has realised she’s been tricked, they’ve already mated! Two words for you: Absolute. Scoundrel.

And even when a male dance fly is honourable and offers a dead fly to the female as a nuptial gift, males will often break off after sex and use the remains of the half-eaten gift to attract a second female. It’s like going on a date and offering a half-eaten box of chocolates to a second date! Two more words for you: Unbelievable. Cheapskate. 

So, now you know about the outrageous deception that goes on in dance fly courtship, how about we play a game exploring the extreme lengths different animals go to, to secure a mate. That’s right, it’s time for a quick round of Fool For You.

Fool for You is a role-play game. We’re going to try to woo you, animal-kingdom style. You have to decide if these moves are genuine courting ​rituals that help animals score in the natural world, or if we’ve just made them up... 
Scenario 1: We’re walking through the park. It’s a beautiful day. I turn to you, raise my impressive crest, suddenly whip my tail against my body and waft chemical signals right at you. Is that a real courtship ​ritual or are we making it up? 
ANSWER: That’s a real one. That ​ritual belongs to the ‘smooth newt’. Presumably named by someone who witnessed that smooth, smooth move.
Scenario 2: I spot a love rival approaching us. Quick as a flash, I raise my wings out to their full span and start frantically regurgitating lunch on the love rival, whilst beating them with my feathers. Is that a real courtship move or baloney? 
ANSWER: That one is made up. Well, I think it is.  Who honestly remembers every night out they’ve ever had?
Scenario 3: Bending down – bear with me – I start to build you a tower of sticks, decorated exclusively with blue objects. When the tower is finished,  you inspect it and decide whether you’re going to let me dance for you. My romantic chances now hinge entirely on this dance. Real or not? 
ANSWER:  This one is real. Male bowerbirds build elaborate towers of sticks to impress females. And, I imagine, they get extra points if they can skilfully remove the sticks, one by one, without the tower collapsing. Hours of romantic fun. 
Scenario 4: I look warmly into your eyes as I lovingly offer you a wrapped-up piece of wood. Real or not?  
ANSWER: That’s a real one. It’s actually humans who do that. Fifth anniversary: wood. Though by year five, I’m not sure how often it leads to mating. 
And finally: the sun begins to set gorgeously over the horizon. We’ll both remember this moment for ever. I hand you a rodent impaled on a stick. Real courtship move or not? 
ANSWER: That’s absolutely real! The male great grey shrike will use thorns, sharp branches or bits of wire to impale their prey for mates. Though, to be fair, show me anyone who isn’t wooed by the gift of a kebab and I’ll show you a damned liar. 

And that’s the end of Fool For You. It’s also the end of our look at wonder women dance flies. As both female and male dance flies demonstrate, nothing’s fair in love and war. Now, I must go online and find myself a splendid pair of inflatable abdominal pants. Maybe in navy blue. 

• All previous episodes of Nature Table are available via BBC Sounds and the book is available here:


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Published: 17 Jun 2024

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