Armyworms invade southern Africa

Govts take action as rapidly spreading caterpillars threaten crops

HARARE • Southern Africa has been struck by a pestilence so severe that farmers have invoked plagues of biblical proportions.

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

"Little is known on how this particular pest entered southern Africa," the report stated. "Since this pest is very new in Africa, very little is known on its long-term effects." It was identified as the fall armyworm a few days later.

"It has come in like one of the 10 plagues of the Bible," said Mr 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 for the Conversation website, Professor Kenneth 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 events: a surge in the population of the native African armyworm, plus the arrival of the fall armyworm, an invader from the Americas.

African armyworms eat in hordes as dense as 1,000 caterpillars per sq m, Prof Wilson noted, stripping maize plants bare. The newcomers may be no less destructive.


It has come in like one of the 10 plagues of the Bible.

MR BEN FREETH, who runs a commercial farm in Zimbabwe, on the fall armyworm.

"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," he 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 per cent.

"The situation remains fluid," said Dr David Phiri, the United Nations Food and Agriculture Organisation's (FAO) southern Africa regional coordinator.

"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."

The FAO has set an upcoming emergency meeting to discuss plans to combat the pests.

The Zambian government has acquired insecticides and begun stockpiling seeds to help farmers replenish consumed crops, according to news organisation NPR. Meanwhile, South Africa has planned to import pheromone traps to catch and identify the extent of the pests' spread.

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

Moreover, as moths, armyworms are known to fly great distances.

In 2012, US Agriculture Department entomologists tracked fall armyworm populations travelling from southern Texas to Minnesota.

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


A version of this article appeared in the print edition of The Straits Times on February 16, 2017, with the headline 'Armyworms invade southern Africa'. Print Edition | Subscribe