The mask has been found in a planter in central Malmö and at several nurseries in southern Sweden.
It is described by the Skåne County Administrative Board as "potentially very harmful", since it eats other worms. It can be a threat to food production, since earthworms are so important for the ecosystem as they break down plant parts and create new soil, emphasizes Nils Carlsson, the County Administrative Board's expert on invasive species.
There is a lot of talk about strengthening our preparedness. Then we cannot allow species that risk reducing our food production, he says to Sydsvenskan.
In Skåne, specially trained dogs are training to sniff out the mask.
If the dogs become sufficiently secure, one can scan a large material without having to lift every plant and every pot, says Nils Carlsson to the newspaper.
The Environmental Protection Agency expects to receive a decision from the government next week on emergency measures. This would, among other things, make it punishable not to take action if one discovers the flatworm on nurseries or on one's own plot.