While the Estonian Open Air Museum typically showcases Estonian folk culture, in recent years it has also become home to a foreign exhibit – the Spanish slug. However, this presence is entirely self-initiated, as reported by "Aktuaalne kaamera."

After rains and at dusk, these slugs emerge en masse from ditches and compost heaps, resembling zombies rising from a cemetery in a horror film.

"About eight years ago, we saw just a few isolated slugs. But three to four years ago, there was an explosion. One spring, it seemed the entire museum was full of them," said Anneli Banner, head of the Estonian Open Air Museum's exhibition department.

The museum's farmsteads and even the kolkhoz house's garden plots have been significantly affected.

"They do quite a bit of damage to the gardens. They particularly enjoy pumpkins and zucchinis. They might eat cucumbers when the plants are still small. They are also fond of carrots, eating both the leaves and the roots. When a carrot is already grown, they can start gnawing from the tip, burrowing into the carrot root," Banner explained.

The Environmental Board, which maintains a map of the Spanish slug's spread to which anyone can contribute information about their area, acknowledges that the problem has become more extensive this year.

"The situation has worsened. They have spread to many more places. The greatest spread is clearly in the Tallinn area, especially in new developments where many ornamental plants have been planted, and mulch has been brought in. This is primarily how they spread. One factor that has promoted their spread in recent years is mild winters, which have significantly increased their survival rate," said Eike Tammekänd, head of the nature conservation work bureau at the Environmental Board.

This is also confirmed by the experience of Viimsi Municipality. According to Alar Mik, deputy municipality mayor of Viimsi, Spanish slugs have become very prevalent this year. "The first reports came about ten years ago, mostly from places with nurseries or plant sales. From there, people took them home with the plants, and they started multiplying," Mik said.

Neither the Estonian Open Air Museum nor Viimsi sees a good solution for getting rid of the invasive species. Manually covering tens or hundreds of hectares is not feasible.

"We have about 50 hectares of forest here, and some parts of the forest floor are so full of them that it's impossible to remove them all. We can collect them from yards and gardens, but that helps very little," said Banner.

"The local government hasn't done anything specific because how do you fight them on public land? We need to mow or maintain around 200 hectares of public areas. It's practically impossible to collect them manually," added Mik.

In recent years, the Environmental Board has recommended less frequent mowing to promote species diversity and natural biodiversity. However, they now acknowledge that this has facilitated the spread of Spanish slugs.

"There's a bit of a contradiction here, and we need to think that if there's a problem with these slugs, the green area needs to be maintained, possibly using some control measures. And if there is no spread of these slugs, nature will take care of itself, and the first isolated specimens can be managed by nature," said Tammekänd.

Viimsi Municipality has recently created more flower meadows and hasn't changed its mowing regime, but it is ready to review its current practices.

"Maybe in some places, we need to mow a bit more, check the ditches, review the mowing regimes and frequencies. And where possible, maybe do some manual collection, which could be a solution," said the deputy mayor.

The Environmental Board advises accepting the new situation, as the spread of the invasive species is already too extensive.

"It's probably no longer possible to get rid of them in Estonia, as their population and spread are so wide, and it's impossible for anyone to find all their eggs everywhere," Tammekänd said.

Staff continually collect slugs, and volunteers have also helped, but the fight seems hopeless.

"If you want fewer of them, you should have a golf course lawn, no compost heaps, or any large tufts of grass," Banner concluded.

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