Hundreds of billions of desert locusts swarm some parts of East Africa and South Asia in the worst infestation for a quarter of a century, threatening crops and livelihoods.
The insects which eat their body weight every day, are breeding so fast that numbers could grow four hundredfold by June.
In January, the UN appealed for $76m to tackle the crisis. The figure has now risen to $138m
But so far, only $52m has been received, $10m of which has come this week from the Bill and Melinda Gates Foundation.
The main threats are in East Africa and Yemen as well as the Gulf states, Iran, Pakistan and India.
Most recently, the locusts were found in the Democratic Republic of Congo and swarms have arrived in Kuwait, Bahrain and Qatar and along the coast of Iran.
Hundreds of billions of desert locusts are crowding in parts of East Africa and South Asia in the worst infestation in a quarter of a century threatening crops and livelihoods.
Aerial and ground spraying combined with constant tracking of the swarms are viewed as the most effective strategies.
But Desert Locust Control Organization for Eastern Africa head Stephen Njoka told BBC News aircraft were in short supply.
Currently, Ethiopia was using five and Kenya six for spraying and four for surveying, he said.
But the Kenyan government says it needs 20 planes for spraying – and a continuous supply of the pesticide Fenitrothion.Kenya has trained more than 240 personnel from affected counties in monitoring of locust swarms.
The Chinese government announced in February it was sending a team of experts to neighbouring Pakistan to develop “targeted programmes” against the locusts.
According to reports,they could deploy 100,000 ducks.
Lu Lizhi, a senior researcher with the Zhejiang Academy of Agricultural Sciences, told Bloomberg the ducks were “biological weapons”.
And while chickens could eat about 70 locusts in one day, a duck could devour more than three times that number.
“Ducks like to stay in a group, so they are easier to manage than chickens,” he told Chinese media.