Radio, locusts and snails

I was driving to an away-day yesterday and I got to listen to some radio in the car.

The Material World this week was about locusts and snails. It seems that it's not really known why plagues of locusts occur. Normally they're solitary creatures that are fairly low-key but they also have a gregarious state where they seek out other locusts and start to swarm - eating their own bodyweight everyday and changing their appearance and behaviour. It's recently been discovered how they start to swarm - if you rub the back legs of a solitary locust it goes into "swarm" mode - so a number of locusts together will tend to turn into a swarm. But it's not really understood why they have evolved to do this, though in times of drought or when there are food shortages they tend to be forced together, which triggers the behaviour. It's thought the behaviour might have evolved from times when their diet was short of certain proteins or salts.

The second item was on snails. It turns out that they are a great way of tracking human movements and migrations. If you find a colony of snails that is related to snails from another geographical area, it's probably because some humans knowingly or unknowingly transported them there. And snails are particularly good for tracking movements like this because they themselves hardly move! Other animals and insects are less good for this because they could have moved there under their own steam. A study has found that a number of snails on the Irish coast seem to have some from Spain, possibly dropped off by the defeated Spanish Armada while making it's way round Great Britain.

Great Radio 4. And in the morning I also caught a fascinating In Our Time on Flaubert and Madame Bovary. Which leads me to point you to speechification, a new blog about the best bits of Radio 4.