•FAO says the only way to stop this increased aerial spraying. This is the worst invasion in Kenya since 1970.
•FAO is now seeking Sh7 billion to fight the locusts and provide food to people already affected in Kenya, Somalia and Ethiopia.
Locust population in Kenya could multiply 500 times in the next five months if control efforts are not intensified, the Food and Agriculture Organisation has warned.
FAO said the current warm and wet weather is favourable for the crop-devouring pests to reproduce.
The last time Kenya faced a locust invasion of this magnitude was before 1950.
FAO director-general Qu Dongyu said something must be done quickly to prevent one of the worst food crises in the country.
The organisation is seeking Sh7 billion to fight the locusts and provide food to people already affected in Kenya, Somalia and Ethiopia.
Both Ethiopia and Somalia are experiencing their worst locust invasion in 25 years.
In a statement on Tuesday, Dongyu said the swarms could invade Uganda, South Sudan and Tanzania, “if efforts to deal with the voracious pest are not scaled up across the region”.
"Authorities in the region have already jump-started control activities, but in view of the scale and urgency of the threat, additional financial backing from the international donor community is needed so they can access the tools and resources required to get the job done," Dongyu said.
In Kenya, swarms of locusts are moving throughout northern counties of Mandera, Wajir and Marsabit and have reached Isiolo, Meru and parts of Laikipia, according to the Ministry of Agriculture.
On Tuesday, the Meteorological department said the favourable weather conditions will persist for the next five days.
The department's deputy director Bernard Chanzu said western Kenya and the southern part of the country will receive rains this weekend.
"Mainly sunny intervals are expected to prevail from Tuesday to Thursday over several parts of the country," Chanzu said.
"Light to moderate rainfall is expected over several parts of the country on Friday and Saturday."
The rest of the country will remain generally dry, the Met said.
Desert locusts are considered the most dangerous locust species. Swarms potentially containing hundreds of millions of individual desert locusts can move 150 kilometres a day with devastating effects on rural livelihoods.
According to the FAO, “given the scale of the current swarms, aerial control is the only effective means to reduce the locust numbers”.
The UN agency said it is assisting with forecasts, early warning and alerts on the timing, scale and location of invasions and breeding.
Dongyu warned the response must include efforts to restore people’s livelihoods.
"Communities in Eastern Africa have already been impacted by extended droughts, which have eroded their capacities to grow food and make a living. We need to help them get back on their feet, once the locusts are gone," he said.
Locusts are the oldest migratory pests in the world. They differ from ordinary grasshoppers in their ability to gregarize, or change behaviour, and form swarms that can migrate over large distances.
During plagues, desert locusts can easily affect 20 per cent of the earth's land, FAO says.