Bugs Matter - a citizen science approach tracking insect numbers

Butterflies flying over wildflowers. — Marbled Whites © Jon Hawkins Surrey Hills Photography

By Rosie Bleet, Ecological Evidence & Citizen Science Lead, Kent Wildlife Trust

The downward trend in insect abundance has been hitting the news in recent years with headlines of “insectageddon” and “collapse of nature”. These may seem a bit over dramatic, but with figures to back them up like over 75% decline in flying insect biomass over 27 years in Germany, and the abundance of larger moths declining by 33% over 50 years in Britain, you can understand the reason for this attention grabbing.

In response to some of these headlines, colleagues at Kent Wildlife Trust were pondering what we could do to monitor insect abundance in Kent in a simple way that non-experts could get involved in. The RSPB ran the “Big Bug Hunt” survey in June 2004, where the public counted the number of insect splats on their vehicle number plates. This method was based on the “windscreen phenomenon” where people tend to observe fewer insects on their vehicle windscreens now than some decades ago. Trialing this survey in Kent in summer 2019 was the start of what was to be a much bigger survey called “Bugs Matter”.

A soldier beetle holds onto the tip of a leaf. — Soldier beetle © Jon Hawkins Surrey Hills Photography

The concept was a simple one and quick to carry out:

clean your front vehicle number plate
record the journey start time
record the journey end time, mileage and count the number of insect splats within a cardboard grid called a “splatometer”, submitting a photo of the number plate with the record

The survey evolved in 2021 with the launch of a simple, freely available mobile app to track the journey route and enable splat count and a photo to be submitted. Buglife joined as partners on the project, helping the survey to have a wider reach than just Kent. In 2023, we made the survey even easier to participate in with the removal of the “splatometer”, and now we count all splats on the number plate. The survey period is also extended to run from May through to the end of September each year.

An image of a phone showing the Bugs Matter app. — Bugs Matter app homepage (Kent Wildlife Trust)

After each survey season the data is cleaned and analysed using statistical models. A range of variables are included in the models to account for their effects on insect splat rates, to obtain more accurate estimates of change over time. These include the time of day, length, and average speed of the journey, the vehicle type, the local temperature, the habitats surrounding the journey route, and the proportions of the journey conducted on different road types. The analysis is also conducted for different regions.

A zoomed in photo of two flower bees hovering above a small mound of earth. — Flower bees © Jon Hawkins Surrey Hills Photography

From a total of 667 journeys in 2019, annual participation has grown to over 10,000 journeys logged in 2025. We have also expanded the survey from Kent to the UK and, as of 2025, the Republic of Ireland. The latest figures indicate an average annual decline in flying insect abundance of 19% per year, which equates to a 59% decrease between 2021 and 2025. For further results and statistics, explore our Bugs Matter dashboard (beta version): https://webapps.kwtg.uk/public/app/bugs-matter-dashboard

These initial results are very alarming and mirror the various other studies and monitoring programmes both within the UK and globally, which show a general downward trend in insect populations. Climatic factors could be partly at play here, for example the wetter, milder winters we have been experiencing in the UK in recent years, which are in stark contrast to the driest spring in over 50 years we had in 2025. While the data collected so far are really valuable and over 10,000 people have registered for the survey, we need even more participation to enable us to better understand the trend in flying insect abundance. This will help to identify the most important factors at play when it comes to the drivers of insect decline.

Bugs Matter is a simple, standardised survey that has the potential to be a mechanism through which we can accurately monitor flying insect populations across the globe. Help us by taking part in 2026 and beyond: www.kentwildlifetrust.org.uk/get-involved/our-projects/bugs-matter You can even continue on your holidays as we plan to launch the survey in France in 2026 and other countries in the years to come.