The U.N. Food and Agriculture Organization said it seeks $22 million to curb the crisis, noting it expects two-thirds of the island country, off the coast of Africa, will be infested by locusts by September.
At stake is the food security and livelihoods of 13 million people, or nearly 60 percent of the population, the organization said in a statement.
"If we don't act now the plague could last years and cost hundreds of millions of dollars. This could very well be a last window of opportunity," said Food and Agriculture Organization Director-General Jose Graziano da Silva.
The funding would be used to mount a full-scale anti-locust campaign, the statement said.