Hello and welcome to more or less on the BBC World Service, where you're weekly

guides to the numbers in the news and in life. I'm Daniel Gordon and as a new

member of the team, the challenge I've been set for my first program is to try

and answer this question sent in by a listener in the southeast of England.

Dear more or less, I ask my mum, how many butterflies are there in the world?

We looked for this information online, but we can only get the details of how many different

species there were. Are you able to answer my question? Many thanks from Bethan, age 9.

So, I got to work, emailing and bringing experts, museum curators, nature enthusiasts, conservationists,

le pedoptorists, which is the official name for a scientist who specialises in

moths and butterflies. Le pedoptorists who are willing to come on more or less and answer Bethan's

question are definitely a rare species, but I did eventually find one.

Hello, I'm Professor Jane Hill. I work at the University of York in Northern

England and I'm really interested in butterflies. I've been researching them for the

best part of 20 years, so I'm really proud to be the president of the Royal

Entomological Society as well. So, first of all, in terms of how many

individual butterflies are there, well, I'm afraid the very quick answer to that is

well, we don't really know, but we could start breaking it down, and the first thing

to be thinking about is how many species of butterflies there are, and we think

there's probably somewhere around 18,000 butterflies species on Earth.

But if you know how many species there are, can you use that number to calculate

the global total number of butterflies? Well, scientists certainly have done that

kind of thing in the past. Professor Hill gave me a quick history lesson.

...