Residents of Embu County are worried as desert locusts have been sighted at Kiambere and Mutuavale villages of the arid Mbeere South Constituency.
Reports indicated that the swarms were first seen on Friday evening, damaging shrubs, green pastures and millet.
Mbeere South Deputy County Commissioner Charles Igiha said the voracious feeders entered Embu from Kitui County, through Isako.
Mr Igiha said the Agriculture ministry was informed of the invasion, whose seriousness he noted in his appeal for urgent action.
"Locusts are a menace. They should be eliminated before they wreak havoc on farms," he said.
Mbeere South member of Parliament Geoffrey King'ang'i asked residents to monitor the insects' movements.
Some villagers said they were afraid that without urgent measures, the insects would ravage their crops.
"The locusts are spreading very fast and are many. We are worried because they are feeding on trees and the grass for our animals," one said.
Another said they expected a bumper harvest following heavy rains but may end up with much less.
Kiambere Ward Representative Lenny Mwaniki described the situation as serious and called for quick intervention by the government.
"The locusts are destroying all plants. They should be controlled before they clear everything," Mr Mwaniki said, and warned of a famine if measures such as spraying are not taken.
The appeal has remained the same in at least 10 other counties affected by the invasion so far - Isiolo, Samburu, Wajir, Garissa, Marsabit, Laikipia, Mandera, Kitui, Baringo and Turkana.
Residents want the government to act quickly to ensure food security and cushion farmers from losses, but officials have admitted challenges in aerial spraying, including lack of enough personnel, aircraft and pesticides, as well as training.
Agriculture Principal Secretary Hamadi Boga, who on Thursday supervised aerial and ground spraying in Lengusaka in Samburu East, admitted that the government was struggling with inadequate resources.
The PS said only five aircraft used for spraying and four helicopters for surveillance were at their disposal.
The Food and Agriculture Organization of the United Nations has warned that the situation could worsen if authorities do not act fast to contain the marauding swarms.
The FAO says the weather has fuelled the insects' movement, meaning the spread may not end soon. The agency added that the pests could multiply 500-fold by June if unchecked.
The UN has released $10 million (Sh1 billion) for aerial spraying in response to the worst locust outbreak in decades to hit East Africa.