Crowdsorsa's away game starts again in Riihimäki

Crowded alien species control will begin again in Riihimäki on Monday, June 1. This summer, Riihimäki residents can earn rewards by eradicating harmful giant balsam and Canada whip using the Crowdsorsa mobile game.

A total of 3,230 euros in rewards are up for grabs for those who participate in the game. The reward is a maximum of 25 cents per square meter, depending on the density of the vegetation.

Everyone can participate in the control work by downloading the application to their own smartphone. The application has a separate task for each plant species. The control of the Canadian whip will begin on July 27, 2026.

"We hope to see even more participants in the Crowdsorsa mobile game this year, and with it, increased awareness of invasive species. The Canadian whiptail, which is one of the newest invasive species, was added to the game as a new addition for the end of the summer. More observations of the Canadian whiptail are needed in the Riihimäki area," says invasive species coordinator Anne Kulhoranta.

Invasive species are plants and animals that spread to new areas through human intervention and displace native species. Harmful alien species reduce biodiversity and can cause significant costs in environmental management.

In Riihimäki, crowd-sourced alien species control is already an established part of nature conservation work. This is the second time the city has participated.

This year, the eradication of giant balsam in particular will be encouraged with higher rewards than usual. The tasks will begin well in advance of the seeding stage of the plants, so that the control is as effective as possible.

“We have only positive experiences with the game from last year. We hope that the game will inspire us to play and fight giant balsam and Canadian whip this year as well. Last year, the players were 17–22 years old, and 20 people or teams were playing. The area controlled was almost 6,500 square meters,” says Saila Nummela, park manager.

This is how prevention works

The player searches for alien plants in the game area of ​​the app's map. Especially in early summer, when the growing season begins, identifying the leaves of plants is important, as the colorful flowers do not appear until later in the summer.

When the player finds a suitable site, they walk around it and record a video. After eliminating all the invasive plants in the site, they walk around the same area again and record a video of their work. A red plant icon appears on the map to mark the area they have just cleared.

A target that has already been eradicated can be re-controlled as soon as the plant icon marking the occurrence on the game map has changed from red to green. This happens approximately two weeks after the first control. Re-controlling ensures that the alien species are eradicated from the areas as accurately as possible.

A total of over 3,000 euros in prizes will be awarded.

This summer, a total of 3230 euros in rewards are up for grabs for those participating in the game in Riihimäki. Players can earn up to 20 euros per hour. The amount of the reward is automatically determined based on the area and density of the deposit.

There is game time until at least the end of September or as long as the reward budget lasts.