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CrowdScience: How many flies have ever existed?

Discussion & Talk

How many flies have ever existed?

28/06/2024 GMT

BBC World Service - CrowdScience, How many flies have ever existed?

Flies are everywhere. But just how many have ever lived?

You can find flies everywhere. But listeners Jenny and Kai want to know just how many have ever lived. Caroline Steel prepares herself to calculate a very, very large number.

The CrowdScience team like a challenge. And listeners Jenny and Kai in the UK have come to us with a big one. They want to know how many flies have ever existed.  

Flies first appeared around 270 million years ago, so presenter Caroline Steel prepares herself to calculate a very, very large number indeed. She enlists the help of Dr Erica McAlister, Curator of Flies at the Natural History Museum in London. As Erica introduces her to specimens from the Museum’s collection of over 30 million insects, they start with the basics. Like... how do you define a fly in the first place?

Caroline also explores the incredible diversity of flies… from fast-moving predators like robber flies which catch other insects on the wing to midges which are a vital part of chocolate-production; and from blood-sucking mosquitoes which transmit fatal diseases to the housefly buzzing lazily around a room. 

And that leads to another fly-related question. Listener Brendan in Colombia wonders why they always fly in circles around a particular area of his apartment. For an explanation we turn to Prof. Jochen Zeil from the Australian National University who reveals that this apparently aimless behaviour is, in fact, a battle for sex.  

And Collin in Barbados has e-mailed to ask how flies and mosquitoes benefit us. He’s had first-hand experience of their negative effects through contracting the disease chikungunya from a mosquito bite so he’s wondering if these insects are anything other than a nuisance. However, passionate fly advocate Erica McAlister is ready with plenty of reasons that we should be extremely grateful for them!

Contributors: 
Dr Erica McAlister, Natural History Museum, London 
Dr David Yeates, Director, Australian National Insect Collection 
Prof. Jochen Zeil, Australian National University 
Prof. Jo Lines, London School of Hygiene and Tropical Medicine 

Presenter: Caroline Steel 
Producer: Jeremy Grange 
Editor: Cathy Edwards 
Production Co-ordinator: Ishmael Soriano 
Studio Manager: Sarah Hockley

(Image: Close-up of insect on leaf, Kageshwori Manohara,Bagmati Province,Nepal. Credit: Aashish Shrestha)

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