Invasive Species Are Once Again Controlled With a Mobile Game In Rauma – Spanish Slugs Included
News
The City of Rauma will continue combating harmful invasive species using the Crowdsorsa mobile game in summer 2026. The campaign offers residents of Rauma an easy and concrete way to take part in protecting local nature while also earning money for the control work they carry out. Over the summer, a total of €5,750 in rewards will be distributed in Rauma.
Participation is open to everyone and only required downloading the Crowdsorsa mobile game to a smartphone from the app store. After downloading the game, participants can remove invasive species already marked on the map or ones they have identified themselves, as well as follow the progress of the control work and the rewards they accumulate. Instructions for identifying and controlling invasive species are also available in the app.
This summer, the species being controlled are Himalayan balsam and lupine, which can be tackled starting 8 June. Both plants spread efficiently and displace native vegetation, weakening biodiversity. Each lupine or Himalayan balsam site is recorded on video before and after removal. The videos are uploaded to Crowdsorsa for review, and approved control actions are rewarded.
Slug task complements the control work
This year, in addition to plants, the campaign also targets Spanish slugs, a particularly harmful invasive species. They cause significant damage in nature and gardens and can even spread diseases. Participants in the slug task collect and euthanise Spanish slugs they find in the field.
–Instructions for identifying and euthanising Spanish slugs are available in the Crowdsorsa mobile game. The City of Rauma provides waste bins for the slug task, and thei emptying is handled by the waste management company, says Office Horticulturist Pirita Sorsakivi.
Collected Spanish slugs are delivered in a sealed one-litre container to slug waste bins marked in the app and documented on video. There are a total of six slug bins and their locations can also be found in the Crowdsorsa app.
The slug task starts on Monday, 1 June. For each litre of collected slugs, participants earn €8 per litre in early summer and €4 per litre in late summer, encouraging effective control before the slugs begin to reproduce.
Teenagers and people aged 30–39 were the largest user groups in the Crowdsorsa game in summer 2025. Among users who submitted a payment request, the age range was 13–48 years. Last year, a total area of 32,950 square metres of lupine and Himalayan balsam was controlled.
