SA farmers battle to control locust swarms of biblical proportions

A swarm of locust take over a farm in the Northern Cape, South Africa. (Photo: Supplied)

By Tembile Sgqolana

15 Mar 2022

According to Agri SA, this is one of the biggest locust swarms in years and, with the assistance of donors and the Department of Agriculture, farmers are trying everything to save their land and food.

Farmers in the Northern Cape, Western Cape and Eastern Cape Karoo are struggling to control the locust swarms that have damaged and consumed thousands of hectares of grazing land.

According to Agri SA, this is one of the biggest locust swarms in years and, with the assistance of donors and the Department of Agriculture, farmers are trying everything to save their land and food.

Northern Cape farmer Barry Naude said the locusts had caused a huge amount of damage to his farm.

“Considering that we just came out of four years of drought and we received our first rains in November last year. In the farms that they have rested on, they have caused absolute mayhem,” he said.

Naude said he had lost the grazing land for his sheep.

“In a couple of weeks, we will go to minus degrees as it is winter, and the veld that has been damaged and now going to winter is a lot. They have eaten tonnes of food and have done a lot of damage to us,” he said.

The locusts arrived at his farm in Richmond in the Northern Cape on Wednesday afternoon and settled there, only flying away on Thursday afternoon.

“They left behind a trail of devastation. This must count as one of the biggest swarms in recent times… it covered an area of about 5,000 hectares… about 10,000 rugby fields,” he said.

Naude said that on Friday the locusts flew to Middelburg in the Eastern Cape.

“The chopper has been spraying them for the past three to four days,” he said.

Andrea Campher, Agri SA’s risk and disaster manager, said it was one of the biggest locust outbreaks that they had seen in many years.

“The outbreaks are occurring in the Northern Cape, Western Cape and Eastern Cape, basically in the Karoo belt. With the high or above normal rainfall we have seen now, locusts or pest disease outbreaks normally occur. It’s a normal phenomenon that locusts break out during high rainfall seasons, especially in dry and semi-arid areas such as the Karoo,” she said.

Campher said there had been massive locust outbreaks in the Northern Cape and Western Cape.

“They are estimating that some of these swarms are reaching 5km by 20km in diameter. Some say there are swarms that are bigger than 4,000 hectares in diameter. We have also seen outbreaks in the Eastern Cape in Graaff-Reinet and Aberdeen,” Campher said.

A swarm of locust take over a farm in the Northern Cape, South Africa. (Photo: Supplied)

She said the outbreak had exceeded the capacity of control teams on ground level, and aerial support had been mobilised through the government as well as organised agriculture.

“Agri SA has donated more than R500,000 to support aerial spraying across Western Cape and Northern Cape. We received word on Friday afternoon that the Eastern Cape will also need immediate aerial support because the swarms have started flying from the Northern Cape and Western Cape towards the Eastern Cape.”

She said it was critical to control the outbreak before it reached irrigation areas as it would damage crops, including maize and sunflowers.

“It’s now at a critical stage where the swarms have started flying and the ground teams, as well as aerial support, are working nonstop to control these outbreaks. We are calling on the private sector to make donations so that we get aerial support. The department supports us with poison,” she said.

One of the people who have been doing aerial spraying, Christof Vermeulen, said their biggest challenge was getting supplies of poison.

“We do have poison for Tuesday, but there is no poison for tomorrow, Wednesday,” he said.

Vermeulen said the ground crew had been working since November without getting paid.

“The ground crew is now reluctant to continue as they have not been receiving any income. The lack of payment will lead to every farmer having to spray their own farms themselves. It’s going to be every farmer for himself. Farmers don’t have the equipment to control the locusts effectively.”

He said their helicopter was spraying 100 hectares every 20 minutes.

“The locusts have done huge damage to the Eastern Cape. Now we are trying to stop the locusts in Middelburg before they go to Cradock where there is an irrigation zone. We are trying our best to control them, but with the government not having enough poison we are in trouble,” he said.

Professor Frances Duncan, the head of the School of Animal, Plant and Environmental Sciences at the University of Witwatersrand, said the swarms are of the brown locust, Locustana pardalina, which is well adapted for living in dry areas.

“They mainly exist in the semi-arid Nama Karoo,” she said.

“The females will lay eggs in dry soils and the eggs can cope with lack of water. Eggs can remain in the soil for at least one to two years in a dormant state, and maybe longer. The female locusts tend to lay their eggs in the same area year after year, creating a build-up of eggs in one area over the non-outbreak years.”

She said there are always solitary (non-swarming) locusts present in the Karoo and some eggs hatch with very little rainfall, ensuring that the population of locusts continues.

“These solitary females continue adding eggs to the egg-bed areas. With early summer rain after a drought period, the eggs hatch and hoppers emerge. Due to the build-up of eggs, hundreds of hoppers emerge at the same time. These then interact with each other and start developing into the gregarious phase which will form the locust swarms,” said Duncan.

She said after experiencing an eight to 10-year drought, the Nama Karoo had above-average rainfall, which resulted in the locust swarms.

“The gregarious locust females lay their eggs together as they mate in the swarm and continue in the swarm to lay eggs. This also creates an egg bed and so with further rains these eggs hatch and large numbers of hoppers emerge. Thus the swarms continue in the region.”

Duncan said previous studies had shown a strong correlation of brown locust swarms with La Niña and El Niño events.

“Currently, South Africa is experiencing above-average summer rainfall as a result of a weak La Niña event, which is one phase of a three-phase climate cycle called the El Niño-Southern Oscillation. As locust swarming is linked to climatic events one would expect that climate change will change the swarm cycles.

“During years of prolonged drought there are no locust swarms but the egg build-up continues. These eggs will hatch with the onset of early and good summer rains. Thus, climate change may affect the frequency of locust swarms and the periods between locust outbreaks. It does depend on how the Nama Karoo is affected by climate change. If the area becomes drier and hotter, then the brown locust will probably survive but there will be a longer period between locust swarms.”

Duncan said surveillance of the locust outbreak area to find the hopper swarms would be the most effective way of stopping locust outbreaks.

“Hopper swarms can be more easily controlled by chemical spraying than the adult locust swarms.”

Hopper bands can walk between one and two kilometres a day, and roost in bushes at night. The application of chemicals on these bushes in the early morning, before the hoppers warm up and are able to move, would kill most of the hoppers.

She said there was limited surveillance of the Karoo due to the sparse population and large size of the farms.

“Once the hoppers reach the adult stage they can fly and move over greater distances. The brown locust is unique in that it will fly at night as well as during the day. Aerial insecticide spraying of adult swarms has a detrimental effect on the other insect fauna and on birds and other predators which consume poisoned locusts.”

She said targeted spraying of the roosting hopper bands probably has a less detrimental effect on the ecology of the region.

“Other methods of control have been investigated, but currently chemical spraying is being used. If the farmers manage to identify egg beds then these could be closely monitored. Due to the importance of grazing in the Karoo region, it is not feasible to plough the area containing the eggs. If the adult swarm settles in crops then ploughing would destroy the eggs.”

Duncan said locusts can be used as animal feed, but are difficult to catch in large numbers.

“The birdlife increases with the onset of locust swarms, and locusts are eaten by other predators.

“There have been reports of lanner falcons following swarms to eat the locusts. But due to the large numbers of locusts, these predators do not control the population. There are no good ways for a farmer to protect their farms,” she said.

Duncan said the Department of Agriculture had investigated chemical control of locusts, but some years ago the locust research unit was closed.

“We need to get a better understanding of the locust behaviour so that a better control strategy can be developed,” she said. DM/OBP

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