Parakontikia ventrolineata

Parakontikia ventrolineata are an invasive species originally from Australia that have been invasive in the UK since 1840. Although they are well-known from Guernsey, they were only recorded in Alderney for the first time in 2024.

The flatworms can be identified by their dark colouration with two light grey lines near the mid-line and are 20 – 40 mm long and 2 – 4 mm wide. They are active year-round, and found on the soil surface in damp places, such as under plastic or other sheeting, rocks, flat stones and plant containers. For ID sheets see the resources linked at the bottom of this page.

What risks do these flatworms pose?

These flatworms are less immediately concerning than Australian flatworms, and there are few known ecological impacts from other areas. They are generalist detritivores (scavenging on dead animal or plant matter), and are also known to eat small snails. There may therefore be a small ecological impact, but we do not anticipate the same kind of impact on soil health seen with the Australian flatworms.

There is some evidence for these flatworms burying into dead fruit, particularly strawberries and apples, meaning there are potential impacts on recreational and commercial growers on island.

What you can do

We currently don't know how widespread the flatworms are across the island. You can help by reporting any sightings using this form or by using the iRecord smartphone app (available for Apple and Android).

Additionally, it's important to maintain good biosecurity processes to check for flatworms, minimise their spread, report any found and kill them.

Checking for new invasions
- Inspect incoming consignments of plants, especially around the root ball
Checking for existing flatworms
- Check regularly under matting or pots standing directly on the ground for flatworms or their egg capsules
- Lift plants from their pots frequently to check for the presence of flatworms or their egg capsules
- Set traps
  - Place a weighted down sheet of black plastic or plank of wood. Check the underside of these traps frequently for the presence of flatworms or their egg capsules.
  - A reporting form is available for sightings at https://www.alderneywildlife.org/report-invasive-flatworms
- ID flatworms using GB Non-native Species Secretariat ID guides, available at https://www.nonnativespecies.org/non-native-species/id-sheets/
Disposing of existing flatworms
- Drop flatworms into boiling or salted water and leave in a sealed container for several hours before disposing of the water (no further precaution required).
Minimising spread:
- Maintain good plant hygiene
  - Always use fresh, sterile compost or other sterile growing medium when potting up plants, not material taken from places where flatworms might be hiding.
- Inspect all outgoing consignments of plants carefully whether or not they are for export

For further advice on the invasive flatworms, please contact us, visit our Wildlife Information Centre on Victoria Street, or see the resources below.

Resources

Please note that the Alderney Wildlife Trust is not responsible for the content of external sites. Resources from Dr. Hugh Jones are shared with permission.