New Zealand flatworm

Arthurdendyus triangulatus


Habitat: Undisturbed soils near the surface. Under cover such as rocks and stones.

Description: Unlike the well known native earthworm, the invasive New Zealand flatworm does not have the segmented body that is easily recognised. The flatworm does, as the name suggests, have a flattened body that is pointed at both ends and covered in sticky mucus. Colour can vary making it difficult for members of the public to identify but in general specimens are grey, or brown, with a pale yellow margin and underside covered by specks.

Origin and Distribution: A. triangulatus originates from New Zealand however other species of predatory flatworms originate from Australia and elsewhere.

Impacts: Earthworms form a pivotal function in terrestrial ecosystems in Ireland. They are responsible for aerating the soil and decomposing plant material while also regulating drainage to some extent by creating burrows. The New Zealand flatworm has been shown to significantly reduce earthworm numbers from both agricultural lands and gardens in Ireland.

How did it get here? It is believed that this species arrived in Ireland by contamination of plant potting soil from New Zealand.

Where is it found in Ireland? The New Zealand Flatworm was introduced to Northern Ireland in the early 60’s. It is currently known from all 6 counties in Northern Ireland where it is generally concentrated around built up urban areas such as Belfast. The species is present in the Republic of Ireland but may be under recorded.

Prevent Spread


• Inspect incoming consignments of plants

• Maintain good hygiene

• Inspect your site for flatworms

• Check plant products for flatworms

• Report sightings


Further guidance and ID downloads;

Invasive Species Ireland

Invasive Species Ireland