Lack of effective pesticides is hampering efforts to contain desert locusts that have invaded several counties and caused worry about food security.
The insects were first sighted in Wajir, Mandera and Marsabit counties and have so far spread to Garissa, Isiolo, Meru, Laikipia and Samburu, where they have left a trail of destruction.
On Thursday morning, three swarms of locusts were spotted at Kipsing, Shaba and Serolipi in Isiolo and Samburu counties.
On Thursday, Agriculture Cabinet Secretary Peter Munya admitted that pesticides used for aerial spraying in the latter counties were ineffective and that the government had been struggling to the find most effective ones.
"The biggest challenge has been getting effective chemicals to kill the locusts. The first pesticides were not effective but we have procured 6,000 litres of chemicals that will be delivered today," he said, noting the batch was better.
"It is true that we have taken some time to contain them but I assure Kenyans that we have put enough mechanisms in place and are now well prepared to deal with the situation," he added.
The chemicals will be used in Isiolo, Meru, Laikipia, Samburu and Marsabit starting Friday.
Speaking at Ngaremara market in Isiolo County, the CS said the government's plan was to kill the pests before hatching, expected to take place in two weeks.
He said the plan also entailed countering the insects at their entry points in Mandera and Marsabit counties to stop their spread.
Mr Munya further noted that the government provided more aircraft for surveillance and spraying.
The Desert Locust Control Organization for Eastern Africa gave three.
The minister dismissed reports that the pesticides had harmful effects, saying they were safe for both people and livestock.
CS Munya said, "They are safe and tested. They are safe for food, vegetation and livestock. People have no need to worry."
While adding that the damage will be assessed after the invasion is contained, he said it was minimal in Meru.
The CS also toured Ndumuru and Kachiuru in Meru.
Meanwhile, leaders including Isiolo North MP Hassan Odha have blamed the government for the spread of the invasion, saying it did not heed the warning of the Food and Agriculture Organization of the United Nations.
Had the government taken the matter seriously, Mr Odha said, the pests would have been contained before invading Wajir, Mandera and Marsabit.
"I am not satisfied ... the government's response in dealing with the locusts has been slow," he said.
The government is racing to contain the invasion that began around December 28, 2019 but has been mum on the components of the chemicals used, amid worries about their effects since farms are also being sprayed.
According to a source at the Agriculture ministry, who is not allowed to speak to the press, the government is training national and county government officials, as well as agricultural officers in affected areas, on safety.
"We have trained 10 officers from every affected county and will conduct sensitisation campaigns for residents before we begin spraying," said the source, who would not reveal the identity of the chemicals.
Among the chemicals the FAO recommended are Diazinon, Bendiocarb, Chlorpryrifos, Deltamethrin, Fenittrothion, a combination of Fenitrothion and Esfenvalerate, Lambdacyhalothrin, Malathon, and a combination of Phoxim and Propoxur.
Diazinon is an insecticide used on fruits, vegetables, nutsand field crops. It is also used to make ear tags for cattle.
Diazinon has been used in the United States since 1956 but was banned from residential use in 2004.
It is readily available in local agro vets and is used at a dosage of half a litre of formula per hectare for locust control.
According to the US National Pesticide Information Centre (NPIC) website, Diazinon works by affecting the nervous system.
"Exposure to diazinon affects the nervous system, this can eventually lead to the death of the insect," says the NPIC.
Diazinon exposure through eating or ingestion, skin contact, or inhalation can result in nervous system health effects.
These may include watery eyes, runny nose, drooling, loss of appetite, coughing, urination, diarrhoea, stomach pain, and vomiting.
Longer exposure can cause more severe reactions including muscle weakness or paralysis, rapid heart rate, difficulty breathing, seizures, convulsions or coma.
A 2002 article published by the US Pesticide Action Network (Panna) raised the red flag over the safety of children exposed to the Diazinon and Fenitrothion sprays during locust control exercises in the US.
The Panna report says that among the banned insecticides, Diazinon is particularly hazardous to children.
"Air monitoring of these two pesticides demonstrates that people living near application sites are exposed to levels that exceed acute Reference Exposure Levels for both adults and children.
"For Diazinon, children who live or attend school near farmlands are particularly vulnerable," the article further says.
Among the side effects attributed to repeated exposure to the chemical are muscle twitching or shakes, depression and irritability.
The report further warns that the chemical can cause birth defects for unborn babies.
"Diazinon is a mutagen. Long-term exposure may damage the developing foetus or cause birth defects, nerve damage and/or liver damage," says the document.
Reporting by Waweru Wairimu, Aggrey Omboki and Angela Oketch