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Alien species
Alien species are species that have spread from their natural range to new areas with humans. Among the invasive alien species, especially Spanish sirenians and giant balsam occur in Riihimäki. The city of Riihimäki repels from its own lands, among other things, giant pipes, giant balsams, handsome lupines and Spanish sirens. Non-native species are taken into account in the daily operation of maintenance.
Control of alien species in Riihimäki
You can prevent the spread of Spanish snails in your yard by collecting snails, removing piles of leaves and branches, and keeping the lawn and other yard vegetation short. Check newly planted plants for Spanish snail eggs. Water plants sparingly and preferably during the day. Do not make open compost. And collect dog waste - it attracts Spanish snails to eat! Simultaneous control of Spanish snails over a wide area is important for successful control. In the 2025 season, pesticides have been distributed to residents as part of participatory budgeting.
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The city's park services are looking for partners from associations in Riihimäki to help combat invasive alien species. Unlike previous years, in the 2026 season, the plan is to also involve associations to help combat the Spanish hornet. We are looking for two associations that both commit to organizing three volunteer activities, with a compensation of 500 euros, paid after the third volunteer activity. The volunteer activities should last at least one hour. The associations should organize Spanish hornet control volunteer activities in the parks and green areas of the city of Riihimäki from 1 May to 30 September 2026.
"In the experiment, we are asking local associations for help with the control work and we want to increase awareness of harmful alien species. If the experiment proves successful, we will aim to continue the volunteer cooperation in the coming years. In addition, the park services will continue to organize volunteer activities for residents," says Anne Kulhoranta, the invasive species coordinator.
The extermination teams must commit to organizing the activities in weather conditions favorable for the movement of Spanish snails (humid, rainy weather) or at a suitable time of day (morning/evening dew). The activity and the snail waste must be documented, for example by taking photos or videos. The organizing association must deliver the snail waste to the nearest snail waste bin.
The park services will define the volunteer areas together with the partner and will deliver the necessary equipment to the organizing association. If possible, the park services should be notified of the volunteer day 2–3 days in advance so that we can advertise the volunteer activities with information signs and on social media. If due to circumstances, the Spanish hornbill is not visible, the association can control, for example, the common lupine at the same time. The details of such exceptional cases will be agreed separately with the organizing association.
Registration instructions for organizing chip snail campaigns
Send your association information and a brief description of your association's activities and your ability to organize volunteer work to vieraslajit@riihimaki.fi by April 13, 2026. The selection will be announced during week 16.
Recommendation for property owners
With the start of spring, the city's park services recommend that all property owners in Riihimäki survey their areas for possible occurrences of invasive alien species. Up-to-date information on necessary control measures can be found on the national website vieraslajit.fi, and local advice is available by contacting vieraslajit@riihimaki.fi or by calling 040 624 8431.
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For several years now, Park Services has been bringing 240-liter trash cans intended only for snails to locations selected based on the observations of the department's employees and residents. The snail dumps are placed in places that are also supported by the findings of the map surveys. Garbage can be found in the city from the map service.
First, kill the Spanish rutanas by cutting them in half lengthwise, or by crushing or dropping them into boiling water. The water should be removed before putting the snails in a closed container, for example an empty milk can.
One snail collected in the spring is hundreds of snails less in the fall. A huge thank you to all the hard-working municipal residents for this valuable work to combat alien species!
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We are about to start the Snail Control campaign. Could you be the Etanakummi of your neighborhood? For example, we would like Etanakummi to organize 1-2 snail talks in its own area so that the city's park services would deliver the necessary equipment. In addition, we hope for an active flow of information about the presence of snails and the effects of control work, and we welcome development ideas. Sign up for the activity, contact information can be found below under Contact information.
If you would like to join the active Spanish Snail Control WhatsApp group that was already established last summer, please let us know your contact information.
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Riihimäki was involved in the VieKas LIFE project (Finvasive LIFE+ project) in 2018-2023. The collaborative project focused on combating invasive alien species and increasing awareness of invasive alien species.
The giant balsam control group, which started in 2017 as part of the VieKas project, will control giant balsam annually until 2023. You can learn about the group's activities by watching the response team's video on YouTube.
Learn more about controlling giant balsam and Spanish hornworms by watching the video on Youtube.
The city's park services continue their work to combat giant balsam.
Park services have been fighting and keeping records of giant pipes since the 1990s. Due to the long germination of the seeds, monitoring has also been done in old places where the giant pipe has not been found for years.
