A swarm of locusts has invaded the Mauritanian capital, Nouakchott, after devouring crops in rural areas.
Thousands might need food aid after their crops were devoured
The insects - which can eat their own body weight in 24 hours - descended on the city, also stripping bare what little greenery the desert capital has.
"Within minutes, the sky was brown. Whole trees were bending over with their weight," a resident told the BBC.
Nations across north-west Africa have appealed for aid to fight what could be the worst locust plague in 15 years.
The swarms turned green trees to brown skeletons in a matter of hours and even ate the grass from the pitch of the main football stadium.
Residents lit fires and rattled tin boxes filled with stones to try to chase away the insects, reports Reuters news agency.
"Nouakchott snowed with leaves," said Karen Homer of aid agency World Vision in Nouakchott.
"It's literally a crisis of biblical proportions," she said.
But she added that the real devastation is in the rural areas where crops are being destroyed and thousands could again need food aid.
"It's sad because this year we've had very good rains after years of drought," she told the BBC's Network Africa programme.
The UN Food and Agriculture Organisation has warned that as a result of the heavy rains, locusts are breeding at alarming levels in southern Mauritania and Senegal.
Further south, The Gambia has declared a national emergency.
There are fears that the locusts can spread as far as Sudan, as they can move up to 100km a day.
A ton of locusts - a tiny part of the average swarm - can eat as much food in a day as 2,500 people.
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They swarmed into our yard and within a matter of hours the ground was scatterd with leaves; the tress and plants turned into skeletons. They came in such masses that I was even afraid to go outside. I hope and pray that they don't last long. We did our bit by killing as many as we could.
Joanna, Nouakchott, Mauritania
Not only did they eat my little vegetable garden I was also frightened to dead;. a big brown swarm surrounding everything and that horrible buzzing sound, horrible. I don't understand why we cannot use planes to spray chemicals.
Sobia Manotio, Nouakchott Mauritanian
It is an absolute disaster. The locusts flew into my farm on the outskirts of Nouakchott, and within two hours literally consumed everything apart from myself. We do not know how we will survive the year, the international community has to send aid urgently, for Mauritania and other countries that will soon suffer too.
mukenio, Nouakchott, Mauritania
The big worry, besides crops, is what is going to happen to the pastures : the Sahel is mainly a grazing land for millions of cattle, camels and goats/sheep, providing the mainstay of people's food and livelihood. Locusts swarming just when grass starts growing is very very worrying. Oddly enough, locals are not really worried : they say locusts only come on very good years, and also that plants grow again afterwards and there is always enough left. I wonder whether that will hold this year, as grass will not grow after the end of the rains. We already experienced the swarms in 1988 and once after that - one gets used to them but it is an overwhelming experience, like bush fire or flood.
Nancy Abeiderrahmane, Nouakchott, Mauritania