Cold weather, rains and resilient genetically-modified crops (GMO) have limited the damage caused by an armyworm outbreak in South Africa, the head of Grain SA Jannie de Villiers said on Monday.

Neighbouring countries, such as Zambia and Zimbabwe, who do not grow GMO crops, are suffering larger losses.

“The worm is a tropical worm, so the cooler weather is not conducive for it to multiply quicker and the wetness is having an effect on its ability of fly,” De Villiers told Reuters at an agriculture commodities conference.

The provinces of Limpopo and North West in the north of South Africa were most affected by the caterpillars, which spread southward from neighbouring countries after first being detected in Nigeria last year.

Harder to detect and eradicate than its African counterpart, the Central African fall armyworm prefers maize, the staple crop in the region.

Its invasion follows an El Nino-induced drought that scorched the region last year, leaving millions in need of food aid.

“Currently as we look at the crop we can’t call it a disaster, mainly because of the GMOs and our ability to protect our crops through commercial agriculture,” said De Villiers.

(Reporting by Wendell Roelf; Editing by James Macharia)