Four cities in Finland are offering residents a financial reward for eliminating invasive Spanish slugs, paying six euros for every litre of slugs collected.
The cities of Lappeenranta, Turku, Kerava and Jämsä have each allocated 1,750 euros to the scheme. Residents use the Crowdsorsa app, which records the eradication of invasive species at local level. The app has previously been used to control harmful (invasive) plants such as lupins and Himalayan balsam.
Spanish slugs are known for spreading rapidly and damaging gardens and crops, and they breed readily in damp conditions. Each slug can lay hundreds of eggs. In Lappeenranta, where the slug invasion is particularly widespread, the city's grounds managers have begun handing out slug poison to residents free of charge.
Maisa Hautala, the Lappeenranta city gardener, says: “The situation was already out of control last summer. We received a huge number of reports about slugs.”
Despite the financial incentives, the public response has been fairly modest. Toni Paju, Crowdsorsa chief executive: “I think killing slugs is more unpleasant and takes more effort than, say, tackling lupins.” He pointed to ethical concerns raised by some residents.
A slug “hunt” takes preparation. Participants must collect them wearing gloves or using tools such as scissors, pliers or tweezers to avoid contact, because slugs can carry harmful bacteria such as listeria or E. coli. Effective methods of killing them include cutting the slugs in half with scissors, crushing them with a stone, or boiling water. For many people, Eeva Koponen among them, boiling water is the preferred method of disposal: “Cutting them up sounds rather off-putting.”
To claim the reward, participants must film a video showing the slugs being placed in sealed one-litre containers and disposed of, as instructed, in special waste bins. The video then has to be uploaded to the Crowdsorsa app. If the video is accepted, the money is paid into their account.
The campaign is part of Finland's broader strategy for combating invasive species, which aims to reduce the environmental and economic damage caused by organisms that are not native to the local environment. The campaign does not apply to the grey field slug, which is a native species and is often confused with the Spanish slug.