"We are spraying between 10 and 20 swarms daily on the farm," Nicola van der Merwe, chairwoman of the Britstown farmers association in Northern Cape Province, was quoted as saying.

Van der Merwe said the swarms are about ten square meters in extent, or even bigger." We had one of about one kilometer long by 200 meters wide," she said.

The swarms of wingless locusts (hoppers) were also plaguing other districts in the province where hundreds of swarms had already been "terminated," most of them young wingless locusts just before they start flying.

Locusts, limited to a few species within the grasshopper family, when going into a swarming phase will form massive swarms that can cause immense destruction to crops and pastures.

The authorities in several west and north African countries were on the alert for locust infestations after a huge swarm was reported in northwest Mauritania last month.

The Locust Group of the United Nations' Food and Agriculture Organization warned the national locust centers in Algeria, Mali, Morocco, Senegal and other countries after the swarm of locusts measuring eight square kilometers was reported in Mauritania.