Arion ater, the European Black Slug. Photo by Peter Ardill
A single sample of this invasive European slug was recently found at the South Lawson Park Bushcare site, and the suspected identity was confirmed by Michael Shea at the Australian Museum. Unfortunately, it would seem that this slug is widespread in some, but not all parts of the upper Blue Mountains (and at selected sites in Victoria and SA) and may be spreading into the middle mountains area.
The adult form of this slug is deep black, with some minor individual variations (white, dark brown). It has no shell, and numerous tubercles, similar to raised mini spines, are clearly visible on its back. The slug is 10-15 cms long. According to the Australian Museum, there are no confusing native species. The black colour makes it quite distinctive. They have no known natural predators in Australia.
Collection and disposal by bushcare volunteers may be effective in slowing and perhaps stopping their spread into unaffected areas, and doing this can slow down their overall acclimatisation process. The impact of this slug on native fauna is unknown, so limiting their numbers and spread may minimise any adverse impacts whilst research into this aspect of the problem is being conducted and can be applied.
The mucus of this slug is particularly thick and unpleasant so the use of gloves is recommended. Please try to dispatch them in a humane manner, such as in a lidded container with a small amount of beer, or by freezing. Snail bait placed in the open can harm native wildlife.
Record your sightings at https://www.ala.org.au, the Atlas of Living Australia or via the on-line reporting tool on the Local Land Services Wildlife Sighting Portal at: http://greatersydney.lls.nsw.gov.au/resource-hub/web-tools. You can also enter the portal directly which will bring up a map of the records to date.
Peter Ridgeway at Greater Sydney Local Land Services is aware of their presence in the Blue Mountains and hopes to engage in an education program with local nurseries. Museum Victoria at https://www.museumvictoria.com.au can also help with further information.
Thanks for considering this issue. Peter Ardill, South Lawson Park Bushcare.
Arion ater: the European Black Slug found at South Lawson Park. Photo by Peter Ardill