This post was written by Tom Price and originally appeared on the Catholic Relief Services website.

On a continent where growing enough to eat is a constant battle for millions of families, there is a new threat: the fall armyworm. In a little less than two years, this pest has eaten its way from West Africa, where it arrived, to South Africa and is now damaging crops in virtually every country in sub-Saharan Africa.

“This pest is expected to be a major shock to an already fragile economic situation for many millions of households across mainland sub-Saharan Africa,” said Shaun Ferris, Catholic Relief Services’ (CRS) Director of Agriculture and Livelihoods.

The worm, or caterpillar to be precise, can destroy as much as 70 percent of a famer’s crop, especially maize. CRS agriculture experts around the continent are already reporting 20-30 percent crop losses.

“This is very worrying, as this is only the first year of the fall armyworm invasion,” Ferris says. A report by the Centre for Agriculture and Biosciences International (CABI) in October estimated maize losses due to the fall armyworm will cost 12 African countries up to $6.1 billion per year.

Native to the American tropics, the fall armyworm first appeared in West Africa in January 2016. The problem here, Ferris says, “is that the fall armyworm arrived in Africa with no natural enemies to stop its spread.” The worm is no slouch. In its adult stage, as a moth, it can fly over 60 miles in a single night. This speed has enabled it to cover virtually the entire continent in two years.

As they arrive, the moths lay huge amounts of eggs, and when these hatch, caterpillars emerge with a voracious appetite. Fall armyworm breaks another rule at this point. Most caterpillars are fussy eaters, meaning that they only feed on certain crops. But this hungry caterpillar feasts on a broad range of vegetation. They prefer cereals like maize and sorghum but will eat almost any vegetation. Once fed, they reproduce quickly, living up to their name by gathering in large numbers to eat through the next crop.

Mark Green, Administrator of USAID, describes the fall armyworm as “truly a great challenge to the survival of agriculture in Africa.”

In Africa, the worm has caught farmers off guard, as they are unfamiliar with this new invader. “Reports are all too common of farmers not knowing what to do as this is new for them,” explains Ferris. “Agriculture experts and governments are very concerned.”

Desperate smallholder farmers who do not usually use pesticides often begin spraying to try to save their crops. Not only is this usually an ineffective use of scarce resources — worms over a quarter-inch long tend to survive spraying — incorrect use or over-use of chemicals can be dangerous. Farmers who rarely spray may not know how to use chemicals safely. They often lack protective clothing. Over-spraying and spraying pesticides near to harvested crops can mean poisonous residues enter the food chain.

 “Without knowledge, spraying is likely to be a dangerous and costly waste,” says Ferris. “Education will be the frontline of our response. Unless farmers know what they are dealing with, nothing is likely to go right from there.”

The next step to countering the worm is scouting: searching and calculating how many fall armyworms are in a given area and then alerting farmers. “Following scouting we can recommend safe and effective treatments,” continues Ferris.

If the presence of fall armyworm is detected early, low-toxic chemical sprays can be very effective. “The key is to spot the problem early and then apply the correct treatment at the right time,” says Ferris.

“We are also looking at different ways to get the word out to farmers and to start a dialogue on potential treatment,” he says, noting that the pest has been effectively controlled in the United States.

“With the world changing in the way it communicates, there are new avenues for disseminating vital messages about identifying and controlling this new pest, like through social media,” Ferris says. “The pest is moving fast, but our response is gathering pace too.”