As globalisation and free trade continue and the effects of climate change become more pronounced new species are expected to move to more northerly latitudes. Although this may mean certain crops can be cultivated in regions further north and some growing seasons may be extended in the shorter term, diseases and pests will also spread into new areas.

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Reporting this week, a joint team from the Jean-Lou Justine Institute in France said that the New Guinea flatworm, the only flatworm in the list of 'worst offenders' amongst invasive species compiled by the IUCN, has been discovered in Caen, Lower Normandy.

The discovery is the first time the species has been found in Europe, though 'invasive' flatworms have been discovered in 13 European countries. The New Zealand flatworm, a different species, has been causing damage on the continent for several decades.

Estimated to have arrived in the UK in the 1960s, the New Zealand flatworm feeds on earthworms, which results in reductions in soil quality. It has few known predators, making it more damaging still.  

According to researchers from the Jean-Lou Justine Institute, "This species [New Zealand flatworm] has invaded the whole north of the British Isles, including Scotland and Northern Ireland, and is responsible for significant reductions in populations of earthworms."

The flatworm's presence has resulted in the implementation of measures to prevent its spread in some EU states, and it has never been found in France. However, the discovery of the – potentially more damaging – New Guinea flatworm, in a greenhouse of Caen's Jardin des Plantes, is "clearly very concerning," the researchers said.

Although it was found in a greenhouse, the French researchers said their discovery has worrying implications for the rest of Europe. The flatworm consumes land snails, but in the absence of these will feed on numerous soil-dwelling species, including earthworms.

It is described as being very flat, measuring around 50 mm long and 5 mm wide, with a "black olive colour" back which has a clear central stripe, and a pale white belly. The head is elongate, with two prominent black eyes. The mouth is in the middle of the belly. Although it is a tropical species, the flatworm inhabits mountainous regions of New Guinea, so researchers believe it can survive in relatively cool temperatures – as low as 10 ° C.

Commenting on the find, researchers from the Institute and the French National Natural History Museum said, "[The New Guinea flatworm] represents a new and significant threat to biodiversity in France and Europe, which hosts hundreds of species of snails, some of which are endangered and protected. It is therefore important to consider the implementation of eradication and control of this flatworm."