Australian Flatworm

Fast Facts

Latin name: Australoplana sanguinea

Notable feature: Invasive Non-Native Species (INNS) in the UK

Conservation Status: Not Evaluated

Where in the UK: This Invasive Non-Native Species (INNS) is widespread in South West England, with some populations in Wales and North West England

Australian Flatworm (Australoplana sanguinea) © D.Smith


The Australian Flatworm (Australoplana sanguinea) is a non-native species, originating from Australia; it is considered invasive as it is spreading rapidly and its presence is impacting our native wildlife here in the UK.

The Australian Flatworm has a flattened ordinarily orange body, with a pink head (particularly after feeding).  Colour can vary from orange to a peachy colour.  This flatworm can measure up to 8cm in length.  On close examination a row of brownish or blackish dots can be seen along the pale margin, being dense and close together near the head but sparser and well separated towards the tail. These are light sensitive organs or ‘eyes’ which help the Australian Flatworm to navigate.

This flatworm was first recorded in the Isles of Scilly in the 1980’s, where it was found on Tresco.  Since this time it has been recorded in greater numbers across Mainland UK.

    • Size: Up to 8cm in length
    • Life span: Undetermined
    • Diet: The Australian Flatworm feeds on earthworms (such as the Lob Worm aka Common Earthworm).
    • Reproduction: Suspected to mainly reproduce via fission, the rear half breaking off and regenerating. Egg capsules are seldom found, but is another method of reproduction.
    • When to see:  Mostly active during cooler months, although can be found year-round in cool, dark, damp places. Active at night but can be found in soil, leaf litter, at the bases of plants, or under logs, stones, plant pots and other objects.
    • Population Trend:  Increasing numbers of reports across the UK
    • Threats: There are no recorded natural enemies and no biological or pesticide control methods for non-native flatworms, the key control measure is to prevent their introduction to new areas.
    • Fun Fact:  After feeding Australian Flatworms turn pinkish from their usual orange colouring.

As with other flatworm species the Australian Flatworm is likely to be distributed via the movement of plants and growing media in the horticultural trade.

How you can help: 

Buglife is working to increase awareness of Invasive Non-Native Species (INNS) and their, often detrimental, impacts on our native wildlife and habits.  Working with other organisations to highlight how biosecurity is everyone’s responsibility and that we can all play our part.

Join a recording scheme and log your flatworm finds – send any records/sightings to our flatworm recording scheme – Potwatch!

Follow our biosecurity guidance (at the bottom of the linked page) on flatworms to help prevent their spread and destroy any non-native flatworms that you find.

Do remember that we rely on donations to continue our work.  If you have searched, found and learnt about our incredible invertebrates on our website, please do consider Making a Donation, Becoming a Member or maybe even making a purchase in our shop.  For more ideas on how to support our work find out how to Get Involved.  Thank you 🕷