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You might be forgiven for wondering why someone parked their boat in a field when you look at the above image, but this is in fact what Hartbeespoort Dam looks like after an ‘explosion’ of invasive water hyacinth.

These aquatic plants usually cover only about 5% of the dam’s surface, but in the last two months there has been a resurgence and Hartbeespoort Dam is now nearly 50% covered.

Water-hyacinth blocks waterways and limits boat traffic, recreation, flood control and wildlife use. By producing a dense canopy at the water’s surface, the plant shades out native submersed plant species that are important to wildlife.

Luckily for all the speedboat owner in Harties, the Centre for Biological Control (CBC) at Rhodes University have come up with an effective, and natural solution. The team has been rearing and collecting hyacinth hoppers (Megamelus scutellaris), small sap-sucking insects, about 3 mm long. And these bad boys are hungry.

Last year, the release of 350 000 of these biocontrol agents whittled down the cover of the fast-growing floating plant to less than 5%.

This past Saturday, 82 people were rescued after their pleasure cruise ran into engine trouble after their propellers were entangled in old fishing nets and plant debris. Before the rescuers could arrive, the water hyacinth had surrounded their boat and caused problems with repairs.

“They are little soldiers doing their work with no need for thanks.”

With these little guys doing their work, Hartbeespoort Dam is expected to achieve more sustainable levels of hyacinth cover, for both the wildlife who call it home and the people who come for a day on the dam.

[source:mg/twitter/wiki]