Kenyan authorities are battling swarms of locusts, which are reported to have damaged crops.
A swarm of locusts can devour as much food as 2,500 people
A BBC correspondent says it is the first time such large numbers have been seen in Kenya for 45 years.
The ravenous creatures - which are capable of stripping vegetation in minutes - are laying eggs in remote areas in the north-east of the country.
The Ministry of Agriculture says it is spraying affected areas from the ground and from aircraft.
The BBC's Adam Mynott in the Kenyan capital, Nairobi, says if the locusts are successful in laying eggs, then the threat lies in them hatching as hoppers in about two weeks.
They would then turn into adult insects - which if uncontrolled are capable of devastating any vegetation they alight on.
The insects can eat their own weight in food every day, which means a single swarm can consume as much food as several thousand people.
Locust swarms have been spotted in many areas in the Horn of Africa, but it is the first time since the early 1960s that large concentrations have moved into Kenya, our reporter says.
Africa experienced devastating swarms in 2004 when they swept across northern and western Africa, leaving 60% of Mauritania's population - 400,000 people - needing food aid.