“Things are quietening down but these locusts have laid eggs,” he said in an interview. “EarthRanger has allowed ueas to understand where this has taken place. When conditions are right and these eggs hatch, we will have the resources in place.”

Swarms that spread across the Eastern Cape and neighboring provinces in the summer growing season were as big as 10,000 hectares (24,711 acres) in some cases and the infestation rivaled those seen in 1935 and 1983.

The locusts razed pastures used to feed livestock across large parts of the region, including in areas that were recovering from eight-year droughts. The heaviest rains since records began in 1921 in many districts allowed the insects to multiply rapidly. While citrus-growing areas were infested, the locusts didn’t cause significant damage to fruit trees.

The area is also home to dairy farms and sheep and angora goats, whose hair is used in mohair garments.

“This is one of the biggest we have experienced in history,” said Gunther Pretorius, manager for economics and natural resources at Agri Eastern Cape.

EarthRanger allows farmers to call in reports of swarms, and whether the locusts are at a juvenile hopping stage or already airborne. Those are then logged and tracked on the system, allowing for more efficient allocation of pesticides and resources. They can also decide whether ground teams or aircraft are needed to tackle the insects.

Offered as a free service, the tracking system was developed in 2015 as part of the Great Elephant Census, a program to measure the size of Africa’s savanna elephant population by assessing data from aerial surveys. It was first used primarily to help protect elephant populations.

Waves of locusts often plague the Horn of Africa and Kenya, razing crops and pastures as recently as last year.