Four countries in northwest Africa are being urged to prepare for the likely arrival of swarms of Desert Locusts, the most devastating of the species.

The Food and Agriculture Organization (FAO) has alerted Algeria, Libya, Mauritania and Morocco about the insects which appear to be headed their way from the Sahel region of West Africa in the coming weeks.

Locusts threaten crops and pastures, and FAO says a small swarm consisting of billions of insects can consume the same amount of food in one day as roughly 35,000 people.

To find out more about the alert, Patrick Maigua in Geneva spoke on the line to Rome, Italy, with Keith Cressman, a Senior Locust Forecasting officer at FAO.

Duration: 3'55"