Silver carp

Hypophthalmichthys molitrix

The silver carp is a deep-bodied fish that is laterally compressed. They are a very silvery in colour when young and when they get older they fade from a greenish colour on the back to silver on the belly. These fish were introduced from Germany in 1975 to the Marble Hall experimental fish farm on the Olifants River. Silver carp compete with indigenous species such as yellowfish for habitat and resources.

White garden snail

Theba pisana

A relatively small snail with a shell diameter of 20mm. It is similar looking in shape to the common garden snail (also an invasive species from Europe), but much paler in colour with some specimens being chalky white. They often have broken brown lines along the spirals. Agricultural and garden pest - it is known to damage numerous plants as well as economically important crops.

Red-eared slider

Trachemys scripta

Red-eared sliders are freshwater terrapins or turtles from North America (found in the Mississippi Valley from Illinois via parts of eastern New Mexico). It is listed by the IUCN's Invasive Species Specialist Group as one of the 'Top 100' Worst Invasive Species.

German wasp

Vespula germanica

A medium-sized wasp with a body length of 12-17mm. It has a black and yellow body pattern and looks very similar to the European paper wasp (Polistes dominulus). The antennae are black. These are social wasps and they construct paper-like nests in trees, roof eaves, under rock overhangs and sometimes in underground burrows.

Quilted malania

Tarebia granifera

This aquatic snail has a strongly spiralled and grooved shell up to 30mm long. It is pale yellow to brown in colour. Found in flowing and still water, including rivers, dams, ponds and reservoirs. May compete against indigenous snails and disrupt natural processes in aquatic systems.

European paper wasp

Polistes dominula

A medium-sized wasp with a body length of 12-16mm. It is boldly patterned with black and yellow and almost identical to the German wasp - also invasive in the Western Cape. It has yellow and black bars on the abdomen and constructs communal paper nests in trees, shrubs and under roof eaves.

Reticulate pond snail

Lymnaea columella

An air-breathing snail with an operculum (horny plat on the foot used to close the shell). The shell is up to 16mm long and coiled to the right. It is dark brown in colour, with a reticulate sculpture pattern. This aquatic snail carries various pathogens and may be detrimental to indigenous aquatic species.

Harlequin lady beetle

Harmonia axyridis

A medium-sized shiny orange to red beetle of 5-8mm. The pattern of black spots is very variable and on the pronotum (neck) there is a black 'M' or 'W' pattern which distinguishes this pest from our indigenous lady beetles. Negatively impacts pristine grassland and agricultural crops, as it is a voracious generalist. It can occur in large densities and compete against other indigenous insects.

Redclaw crayfish

Cherax quadricarinatus

This crayfish may attain a length of almost 40cm and weight of 2,5kg. It has a fan-like tail and large pincers. The colour is brown to dark grey and the pincers are steel blue with bright red patches, especially on the outer two sides. These crayfish are not indigenous to South Africa and may negatively impact indigenous freshwater species. It also carries parasites which have further impacts on indigenous species.


Cherax destructor

This crayfish can grow 10-20cm but some individuals attain a length of 30cm. Colour is variable and depends on water quality, but most take on a greyish-blue to vivid metallic blue colour. This is not an indigenous species and may have negative impacts on our wetland systems by competing against indigenous species. The burrowing activity may cause damage to dams and riverbanks.