Cereals growers in North Rift region, the country's grain basket, are staring at heavy losses due to the re-emergence of the Fall armyworm.
The worm invasion has increased production costs and also threatens farm yields.
Several counties in the region are racing against time to contain the spread of the deadly pest, with agricultural experts warning of a looming national food disaster unless the outbreak is contained.
The worm has been reported in Trans Nzoia, Nandi, Uasin Gishu, Kericho, Nyamira, Bungoma, and Busia counties.
It is blamed for the loss of nearly 20 per cent of the two million bags of maize, which was to be last season's harvest.
The pest found its way into the country from Uganda after an earlier outbreak in Ghana and South Africa. It was first reported in North and South America.
Kenya Agricultural and Livestock Research Organisation director general Eliud Kireger said the worm's larvae - caterpillars - cause severe damage to more than 80 plant species, including maize, sorghum, rice, millet, wheat and barley.
It also attacks fodder crops such as Bermuda and Napier grasses, sugarcane and cotton.
Other susceptible crops, include kales, cabbages, legumes, bananas, tomatoes, capsicum, ginger, spinach, onions, sugar beet, citrus, cucumber and sunflower.
"The infestation in maize plantations signals a tough season for farmers since they did not factor the cost of fighting the pests into their budgets," said Mr William Kimosong, the Trans Nzoia branch chairman of the Kenya National Farmers Federation (Kenaff).
Mr Kimosong said a broad spectrum of pesticides recommended by the Ministry of Agriculture was very expensive, with the cheapest selling at Sh20,000 a litre but only sprays one acre.
"This spells doom for us, coupled with the high cost of farm inputs, the drought in some parts of the region and the unstable maize market," said Mr Andrew Rotich, a farmer from Cherangany, Trans Nzoia County.
Kenya Seed Company managing director Azariah Soi said the vicious pest was tolerant to most pesticides.
"Unlike the African armyworm, the Fall armyworm, which is dispersed by wind, burrows inside maize stems and cobs, making it difficult to detect. It can lay up to six generations of up to 50 eggs in one location, leading to rapid destruction," said Mr Soi in a previous interview.
Mr Johnston Irungu, the director of crops in the Ministry of Agriculture, said a technical team had been sent to the affected 42 counties to combat the spread of the destructive pest.
He also revealed that some local experts had been sent to Brazil to learn how the country has managed to deal with the menace.