Dozens of tiny black weevils cling onto a fern plant as it is tossed onto a leafy green mat coating the surface of South Africa's Crocodile River.

Dozens of tiny black weevils cling onto a fern plant as it is tossed onto a leafy green mat coating the surface of South Africa's Crocodile River. The plant is steadily taking over freshwater bodies in the northern region of South Africa, suffocating aquatic life, including on the Crocodile River and the Hartbeespoort Dam it flows into.

South Africa is unleashing weevils imported from the United States in a bid to fight off the sprouting growth of Salvinia minima, an alien species of aquatic plant native to South America that is choking up dams and rivers.