The majority of locusts will breed in six counties in two months, the Food and Agriculture Organization has said.
They are Turkana, Marsabit, Samburu, Isiolo, Wajir and Mandera counties.
FAO said control efforts should concentrate in those counties on the eggs and the newly hatched wingless hoppers.
The Agriculture ministry has increased the number of sprayer aircraft from eight to 20.
If the young nymphs are not sprayed, they will stay around these counties as they develop wings, then spread to the rest of the country.
"Hopper bands will continue to form during March and April, giving rise to an increasing number of first-generation swarms that will mature and could be ready for a second generation of breeding from early April onwards," FAO says in its latest advisory.
The government is relying on donors to buy pesticides and spraying equipment.
Last Friday, the USAID provided an additional Sh1 billion to Kenya, Ethiopia, and Somalia for locust control.
"By helping to reduce the size of the swarms, this aid is expected to have a positive impact on affected communities throughout the Horn of Africa," USAID said in a statement.
FAO said in February widespread laying and hatching occurred primarily in the north and some central counties.
Ground and aerial control operations treated at least 15,000 hectares across the country.
Experts say the long rains might slow down the locust infestation, especially in regions receiving above-average rainfall.
However, pesticides remain the most effective way to control the infestation.
Entomological Society of Kenya chairman Muo Kasina told the Star heavy rain can kill eggs by submerging them, causing them to rot or washing them out of the ground.
The floods can also drown large numbers of young hoppers, he said.
"In some areas, they prefer to lay their eggs in moist river beds, which will be submerged if the rivers are swollen," Kasina said.
However, he said, rains can work to the advantage of the pests by increasing foliage that will shelter young hoppers from pesticides.
The IGAD (Intergovernmental Authority on Development) Climate Prediction and Applications Centre said the rains might also bring create conditions for the locust to thrive in, especially in Western Kenya.
"The current wind directions favour locust movement from East to West, from infested to non-infested areas," ICPAC said.
Kasina said rains are unlikely to slow down spraying. "We only need proper forecasting because it is advised that you spray two to three hours before it rains.
"The only challenge is if the pesticide is not available," said the scientist — a member of the Africa Association of Insect Science.
Agriculture CS Peter Munya had said that the government plans to clear locusts by June.
The government has used more than 20,000 litres of chemicals to control the pests.
(Edited by V. Graham)
