The calculator (https://insektentaschenrechner.de/en) predicts the number and diversity of insects and spiders – and brings this knowledge to life. The web tool impressively demonstrates the dramatic impact of mowing: a single mowing operation can reduce the number of insects and spiders in a meadow by up to 73 per cent. Since last year, users have been able to find out for themselves what impact different mowing techniques have. The corresponding scientific study has now also been published in the journal ‘Ecological Solutions and Evidence’. This publication derives the formula – which incorporates twelve influencing factors – for calculating the number of insects per square metre. It is based on the data available to date from various regions of Germany and Switzerland, which also feed into the calculator.
“Our understanding of the biodiversity crisis is growing, but there is still a lack of effective measures and action,” explains lead author Johanna Berger, who carried out the extensive analyses and visualisations for the web tool as part of her PhD at the Technical University of Darmstadt. "A key solution for us in the scientific community is to link our findings to practical applications and communicate them more effectively, for example through digital and data-driven tools such as our Insect Calculator." This is intended to contribute to local biodiversity, as meadows are among the most species-rich habitats in Europe.
The Insect Calculator was developed as part of the BioDivKultur project, which comprises an interdisciplinary research team from TU Darmstadt working with project partners from the field. The project is part of the Research Initiative for the Conservation of Biodiversity (FEdA), which is funded by the Federal Ministry of Research, Technology and Space (BMBFTR, formerly BMBF). The study was carried out in collaboration with other researchers from Germany and Switzerland. In Darmstadt and the surrounding area, signs developed by BioDivKultur featuring ‘Points of Insects’ highlight the importance of various green spaces for insects in many locations – and are linked to the Insect Calculator via a QR code.
Senior author Nico Blüthgen, project spokesperson for BioDivKultur, explains: “For the Insect Calculator, we have compiled a comprehensive dataset from standardised one-square-metre samples of insects and spiders from Germany and Switzerland. On this basis, it is possible to clearly demonstrate how various mowing parameters and the sealed area surrounding green spaces affect the number and diversity of insects and spiders.”
The Insect Calculator offers a ‘Walking Mode’ for the general public and an ‘Expert Mode’ for experts in grassland management. The study found, for example, that unmown meadows are home to 73 per cent more arthropods than mown areas, and this effect is clearly reflected in the calculator. This applies similarly to spiders, cicadas, bugs, grasshoppers and other groups – though to varying degrees.
In less isolated rural areas, the density of insects and spiders is higher than in more heavily sealed urban areas; mulchers lead to a greater decline in insect populations compared to bar mowers, and the varying effects of mowing frequency, cutting height and other parameters become apparent. Co-author Margarita Hartlieb, who was also involved in the implementation of the online tool, adds: "Our web tool provides additional information, such as links to observations from the iNaturalist citizen science project for the specified location, FAQs and insights into the research processes."
Lead author Berger explains: “One key finding is that whilst changes to mowing practices can have an effect – such as using mowers that are less harmful for insects or reducing the frequency of mowing – mowing itself has the greatest impact. This highlights the importance of areas left unmown – so-called refuges. They are an effective measure for protecting insects and spiders, as they preserve resources and provide places for them to take refuge during or after mowing.”
Refuges can also be effectively created using approaches such as rotational mowing, whereby only part of the area is mown at one time, whilst the other part is mown at a later date. On this topic, the ‘Insect Calculator’ web tool also provides a sample calculation at https://insektentaschenrechner.de/en/refuge . After mowing an area of 100 square metres, around 13,000 insects and spiders are found. However, if ten per cent of the area is left unmown, the number rises to 14,350; if 20 per cent is left unmown, it rises to 15,700; and if 30 per cent is left unmown, it rises to 17,050. A completely unmown meadow is home to as many as 26,500 insects and spiders.
Unmown refuges provide habitat diversity, protection from mowing, and areas for larvae to develop and overwintering habitats. The Insect Calculator therefore makes it possible to back up arguments with reliable data, thus supporting objective, evidence-based discussion about the use of green spaces.
Ecological Solutions and Evidence
Observational study
Animals
The Insect Calculator: A web tool to predict meadow arthropods based on mowing impacts
28-Jun-2026