A locust swarm can devour as much food as 1,000 people

Vast swarms of locusts have already arrived in neighbouring countries and a BBC reporter in the Gambian capital, Banjul, says anxiety is growing.

More than 70% of the population in Gambia are dependent on farming for their survival.

The insects can devour within a day food that would feed thousands of people and hundreds of livestock.

One farmer in Gambia told the BBC's Ebrimah Sillah they were already struggling and the last thing they needed was something that would aggravate the problem.

"This is scary. We are just into the middle of the rainy season therefore if the locusts attack today it will be devastating."

The government has established a $1.5m emergency plan and has urged people to be on the alert for locusts.

Appeal

Last week the United Nations Food and Agriculture Organisation (FAO) appealed for $83m (68m euros) to help tackle what they describe as the worst occurrence for 15 years in north and west Africa.

"In the next couple of weeks, the situation will probably return pretty much to normal in north-west Africa, but it will get worse in west Africa," FAO spokesman Keith Cressman told AP news agency.

This year's swarms are especially big due to prolonged periods of heavy rain last year.

The insect swarms have already affected over 6.5m hectares (16m acres) of farmland in north-western Africa and the Sahel region.

Measures to control the spread of locusts appear to have had some success there but, the UN says, heavy seasonal rains in the Sahel region have increased the danger that locust numbers will continue to rise in west Africa.

Locusts can eat their own weight in food every day, which means a single swarm can consume as much food as several thousand people.