Cape Town - Cape Town is battling invasive alien species carrying potentially deadly weapons. Polistes dominula and Vespula germanica arrived in the Cape area in 2008 and have turned into a force to be reckoned with.
The two species are wasps, not a reference to White Anglo Saxon Protestants, but to the insects with the formidable sting in the tail.
Polistes dominula is better known as the European paper wasp, and Vespula germanica as the German wasp.
Although the German wasp is the most aggressive, it has stuck mainly to less developed areas in the Boland, such as Pniel and Franschhoek, and the mountain areas there.
The European paper wasp however, has become a problem in urban areas, mostly in the Tygerberg, Stellenbosch and Eerste River areas, said Dr Ruan Veldtman of the South African National Biodiversity Institute (Sanbi).
“The European paper wasp can be found in urban gardens and around homes and they have been spreading like wildfire,” he said.
“They are also to be found in the farmlands of the Boland, where they even nest in the vineyards. They are probably the biggest problem, because their numbers have grown so fast.
“They do actually do good work by targeting insect pests as prey and studies show they do not have any real negative environmental impact. They do not compete with the smaller indigenous red wasp and there is no indication that the red wasp is being damaged at all,” Veldtman said.
“The biggest problem is they come into contact with people, and they sting. Statistics show that about one in 1 000 people may be allergic to the sting and this could be fatal. The sting is also very painful.
“The nests in the vineyards are a problem too. In February, when it is nice and hot and they are at their most active, they attack the farm workers who harvest the grapes. People have been stung on their hands, arms and faces.”
Veldtman said the wasps could be controlled in the home by using domestic pyrethroid sprays.
“Pyrethroids are not harmful to vertebrates, but people must make sure that they get the types that say ‘fast’, or ‘instant’, on the container.”
The City of Cape Town and Stellenbosch Municipality were working with Sanbi on an eradication programme, Veldtman said. The programme involves clearing by area.