Southern Africa has been struck by a pestilence so severe farmers have likened it to plagues of biblical proportions.

Hungry caterpillars called fall armyworms are on the move across the continent from Zambia southward. In early February, South Africa’s agricultural department issued a report, noting that for the first time that this unfamiliar pest had been spotted in the country’s Limpopo province.

“Little is known on how this particular pest entered Southern Africa,” according to the report. “Since this pest is very new in Africa, very little is known on its long term effects. ” It was positively identified as the fall armyworm a few days later.

“It has come in like one of the 10 plagues of the Bible,” said Ben Freeth, who operates a commercial farm in Zimbabwe, to South Africa’s Sunday Times. “It’s widespread and seems to be spreading rapidly. It can lay up to 2,000 eggs and its life cycle is very quick.”

Armyworms — which will grow into moths and are not, technically speaking, worms — are so named for their ability to destroy massive amounts of crops, in the manner of troops trampling over a countryside. Writing at the ConversationKenneth Wilson, who is studying the use of biological parasites to battle crop pests at England’s Lancaster University, described the recent havoc as the combination of two species: a surge in the population of the native African armyworm, plus the fall armyworm, an invader from the Americas.

African armyworms eat in hordes as dense as 1,000 caterpillars per square meter, Wilson noted, stripping maize plants bare. The newcomers may be no less destructive. “The impact of the fall armyworm is likely to be devastating because it eats the leaves of the plant as well as its reproductive parts,” Wilson wrote. “This damages or destroys the maize cob itself.” He cited an estimate that put Zambia’s possible losses of maize, an important grain staple, as high as 40 percent.

“The situation remains fluid. Preliminary reports indicate possible presence (of the pest) in Malawi, Mozambique, Namibia, South Africa, Zambia and Zimbabwe. Zimbabwe has positively identified the presence of the pest while the rest are expected to release test results soon,” said David Phiri, the United Nations Food and Agriculture Organization’s southern Africa regional coordinator, in a news release.

The Food and Agriculture Organization has set an upcoming emergency meeting to discuss plans to combat the pests. The Zambian government acquired insecticides and has begun stockpiling seeds to help farmers replenish consumed crops, according to NPR. Meanwhile, South Africa planned to import pheromone traps to catch and identify the extent of the pests’ spread.

Pesticides have shown to be effective against armyworms in the past, Wilson noted at the Conversation. But it was not yet known if the current caterpillar outbreak had developed a resistance to the usual chemicals that kill them.

What’s more, as moths, armyworms are known to fly great distances. In 2012, U.S. Agriculture Department entomologists tracked fall armyworm populations traveling from southern Texas to Minnesota.

“Only time will tell,” Wilson wrote, “what the full impact of this armyworm invasion will have.”

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