By Pascale Harter
BBC correspondent in Mauritania
West Africa is in the grip of its worst plague of locusts for generations, with massive swarms infesting thousands of kilometres of land from the Atlantic coast to Chad, eating everything in sight.
When you see locusts up close with their yellow antennae twitching they seem possessed of an alarming intelligence.
Mauritanian officials warn of famine
Ten centimetres long and pale pink, they look like giant shrimps with wings.
Sometimes they score a direct hit, flying into your head and settling in your hair or they crawl up your trousers, holding on with hook-like claws.
And when they fill the air for hours at a time, flying in their millions in one determined direction, it feels like an alien invasion has begun.
It is hard to believe these invaders don't have a master plan.
After all, they are doing so well in the battle against the superior species.
The humans are hopelessly outnumbered.
Mauritania is a vast empty country of less than three million people roaming around a landscape eaten up by desert.
Newly hatched bands of locusts are detected daily
Engulfed as it is in yellow sand, even the capital is easily overlooked, as the aeroplane makes its descent into Nouakchott.
It is hard to believe anything can survive with so little water and so much sand, but 80% of the population makes a living off the land, just about.
Their harvest is their currency. The rice or sorghum they grow will be traded for cooking oil and blankets and used to buy seeds for the next planting season.
Only some will be eaten. Most of the young men have already left the countryside in the south and headed to the overcrowded slums of the capital in search of badly paid work.
They leave behind grandmothers to labour the land who explained to me that as heads of families of eight or sometimes even 10 they have to struggle to survive in a good year.
Sometimes the family eats only every other day, they told me.
Plagued first by years of drought, the Mauritanians welcomed this year's rains as a godsend. But this year God sent something else too.
"They can spray pesticides as much as they like," said one goat herder. "Allah brought the locusts and only Allah can take them away."
"Just be grateful they don't eat people."
But they might as well do if they eat all of their crops.
Local officials in the south of Mauritania have already warned of famine.
They estimate 40% of crops have been eaten so far.
Mahmoud appeared over a sand dune with his son on a donkey cart.
They were herding their thin cows from their village to the nearby town to sell their milk.
Mahmoud told me that the locusts had arrived just three weeks ahead of harvest time, and eaten all of his crops.
Without the milk from their cows, Mahmoud and his family will go hungry, but it is his only chance to buy seeds for the next planting season.
For Mahmoud, the fruits of years of working the land were tied up in this year's harvest.
For him and the other Mauritanians whose crops are wiped out in a single day, this locust plague is biblical in proportion.
"I haven't seen anything like it since before my children were born," one woman told me.
Her children are now in their thirties.
Around Kiffa in the south-east of Mauritania, the worst hit area so far, the sky buzzes, not only with locusts but with low-flying crop duster plains.
For Mauritanians trying to eke out a living in this desert-like scrubland, it is the noise of the resistance movement.
At first light the locust-control pilots set off from their desert camps to spray, but they are up against a moving target and have to use pesticides that will biodegrade, not affecting crops and cattle.
Even when they destroy one swarm, another often arrives the next day, feeding off the corpses of its dead and finishing off the crops too.
In a country so poor the ministry of the environment did not have the money to put petrol in its cars to go out and investigate the first sightings of swarms, vigilant villagers are the locust control centre's early warning system and they are detecting newly hatched bands of locusts daily.
The whole country has put aside its fierce national pride and appealed for urgent international help.
"We Mauritanians can take care of ourselves," a motorist told me, as he tried to run over as many locusts resting on the roadside as he could.
"When we ask for help you know it is serious," he said.
But that help is slow in coming and if more planes and pesticide do not arrive soon, food will have to be brought instead, as the locusts spread famine across half the continent.
From Our Own Correspondent was broadcast on Saturday, 25 September, 2004 at 1100 BST on BBC Radio 4. Please check the programme schedules for World Service transmission times.