Obama flatworms

Obama flatworms (Obama nungara) are an invasive species originally from southern Brazil and Argentina. They were first identified in Guernsey in 2008, but had not been recorded on Alderney until 2025.

The flatworms can be identified by their dark colouration with a white underside and are up to 10 cm long and 1 cm wide, forming a very broad shape sometimes compared to a leaf. They are typically found in wet areas, with sandy soils, but can also be found in garden environments, especially in leaf litter or piles of vegetation. For tips on identifying the species see the resources linked below.

Why we are concerned

Similar to the Australian flatworm, Obama flatworms' diet consists of earthworms, and the presence of both of these invasive flatworms on Alderney is concerning both for the status of our native earthworms, the species dependent on them (including small mammals and birds), and the ecosystem functions that earthworms provide.

Earthworms are often referred to as 'ecosystem engineers' because their presence modifies our soil's physical, chemical and biological properties. They are decomposers, helping release nutrients in dead organic material, and their burrowing increases the availability of these nutrients to plants, along with better water infiltration and improved soil aeration.

Increased earthworm predation by the invasive flatworms is therefore concerning for the future fertility and health of Alderney's soils, and could have negative impacts on growers across the 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).

The flatworms have been found near to gardens across the island, transitioning across roads in wet weather. Normally they are normally found above the soil, and it is worthwhile looking in the leaf litter and under non-porous material like paving slabs, plant pots or tarpaulins for them.

You can also help prevent the spread of the flatworms by:

• Checking soil around new plants before planting, especially around the root ball and inside pots.
• Checking any gardening or farmyard equipment for flatworms before using it or moving it between sites.
• Not giving or receiving plants or reusing topsoil from areas known to be infested, including between infested plots or beds in allotments and gardens.
• Killing any flatworms found by immersing them in salted or hot water and leaving them in a sealed container like a jam jar. You can leave this container for a few hours and then dispose of the liquid without further precaution.
• Treating any infected plant pots by immersing the whole pot (above the root ball) in water >30 °C for 40 minutes.

For further advice on any invasive flatworm, 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.

Factsheets

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• Invasive species Northern Ireland factsheet on Obama flatworms
• Buglife guide to non-native UK land flatworms

More on flatworms:

• Dr Hugh Jones's extension for additional flatworms found between 2005 and 2023 in the UK