PRESS RELEASE
Menacing invasive wasps expanding their range
Two highly invasive wasp species are expanding their range throughout Cape Town and the Western
Cape and officials are calling upon the public to help identify and report new colonies. Having
originated from Europe, these unwanted invaders have found the Cape Metro and Boland to be
ideal habitat suited for their expansion. If left uncontrolled they may spread to the majority of
Western Cape towns and other provinces with climate even more suited to their ideal requirements
The European paper wasp (Polistes dominula) and German wasp or yellow-jacket (Vespula
germanica) is superficially similar to one another. The European paper wasp is a medium sized wasp
(20-35mm) with wavy yellow and black markings on abdomen and orange antennae. This wasp
species flies with its legs hanging, lazy zigzag pattern while searching for prey, carrying chewed prey
items in their mouths. The nests are always above ground and can easily distinguished from those of
German wasps in that the nest cells are visible on the underside of nests. Where present, these
wasps are common on lawns where they forage for caterpillars and other prey. Depending on
density, walking barefoot on lawns could result in accidental stings.
The German wasp is also a medium sized wasp (15-40mm) with yellow and black markings on
abdomen but have and black antennae. On the wing this wasp species is distinctive from the paper
wasp in that the legs are pulled in during flight, and prey items are carried under the body. This
species nests are papery and are normally built underground, however in urban settings they do
sometimes produce the paper ball-like nests above ground under ceilings or inside wall cavities.
Nests can range in size from 200 to 5000 individuals, with a record of 750,000 being recorded for a
farm in Somerset West in 2002! This wasp is aggressive, especially if the nest or surrounding areas
are disturbed.
Both species are listed as NEMBA Category 1b invasives, meaning the species that require control by
means of an invasive species management programme.
Negative impact
According to international cases of invasion involving both species, these insects have the potential
to create problems ranging from nuisance to catastrophic economic impacts in the wine, deciduous
fruit and beekeeping industries.
The German wasp in particular, is aggressive and there are several reported cases of them stinging
workers harvesting grapes and other fruits. They can present a hazard to people and homeowners
enjoying the outdoors who may unintentionally disturb a colony. These wasps also feed on mature
grapes in the late summer months and cause extensive damage to vineyards.
They are also known to attack and kill honeybees and infiltrate bee hives, which is detrimental to the
honey industry. Haupt is currently busy with a survey on the distribution of the German wasp with
the aim of eradicating and control of this species.
Range expansion
V. germanica: first recorded from near Table Mountain around 1974, they have dispersed to areas as
far afield as Stellenbosch, Somerset-West, Grabouw, Franschhoek, Paarl and Wellington.
P. dominula: first recorded from in SA from Brackenfell in 2008, they have quickly dispersed to
Kraaifontein, Kuilsrivier, Stellenbosch, Somerset-West, Gordansbay, Paarl, as well as areas as far
afield as, Grabouw, Franschhoek, and Wellington. For both species localities not listed here should
immediately be reported as potential new distribution records.
Research programme
Research being implemented by SANBI’s Invasive Species Programme, funded by the Department of
Environmental Affairs is trying to determine the rate of expansion and document new colonies and
find solutions to control the spread of both invasive insect species. The project is managed by a
consortium of researchers from the following institutions: Stellenbosch University, SANBI, the
University of Cape Town, the Agricultural Research Council, CapeNature, Iziko Museums, and City of
Cape Town - Invasive species. The Invasive Wasp Research Consortium consists of an
eradication/infestation control as well as communications components. The research programme is
now in its second phase and will move to experimental trials on effectiveness of local eradication of
both species.
Help needed
Authorities are calling on the public to assist them in documenting new colonies so that the
appropriate measures can be taken to control these invaders. For more information, visit
http://www.capetowninvasives.org.za/edrr/target-list where you can find more information and
how to report sightings. Or send an email to [email protected].
Specific enquiries about the research component of the project should please be addressed to Dr
Ruan Veldtman (SANBI) – [email protected] or (w tel.) 021 808 9441