Welcome to Insectcount.dk

This web site presents a project, in which persons interested in nature can make a difference. We will determine the causes of the dramatic fall in the abundance of insects since 1990 and relate this decline to the abundance of insectivorous birds.

About the project

The number of insects has decreased by more than 70% i large nature reserves in Germany, but also in farmland in Denmark during just 27 years. These declines in the number of insects can be measured from the number of insects on the windscreen of cars. The objective of this study is to use citizen science to (1) determine whether the number of insectivorous birds decreases with a decreasing number of insects on the windscreen of cars, and (2) determine the main factors that explain variation in the abundance of insects.


Data collection

Insect counts will be based on the number of insects killed against the windscreen, and the number of house martins, barn swallows and swifts on the same route. This simple measure of the number of insects and the number of insectivorous barn swallows, house martins and swifts should be entered in an excel calcsheet file (download calcsheet).

Please return the completed data sheet to mail@insectcount.dk

The speed of the car should be the approximate speed on the route. If the distance is 5 km, and if the speed is 60 km/h most of the route, then you should enter 60 km/h.

If coordinates are unavailable, leave the space empty

Wind should be scored as Beaufort from 0 to 12

Cloud cover should be in units of 1/8 from 0/8, which is a clear sky to overcast, which is 8/8

When having driven a certain distance and after having stopped the car, count the number of insects on the window. Clean the window thoroughly before starting a new insect census.  Only data for March-August will be relevant.

Assessing insect abundance with a car

The objectives of this study are to (1) determine whether the abundance of aerial insectivorous birds increases with the abundance of insects on car windows, and (2) determine the main factors that explain variation in insect abundance.

Many insects killed on the windscreen of a car on a warm summer day.

Insects are killed after collision with windscreens (car windows) leaving a spot on the window. The abundance of insects killed on windows varies from none or few on cold days and in intensively cultivated farmland to many on warm and sunny days in natural habitats. This measure of insect abundance is highly repeatable on different days and at different times of the day. Insect abundance estimated with a car is also strongly positively associated with insect captures with a sweep-net, sticky insect plates and feeding rates of barn swallows at their nests. Previous use of this method on two transects has revealed reductions in the abundance of flying insects by more than 70% in Northern Denmark during 1996-2017. A German study in nature reserves since the 1970’s also showed a reduction in abundance by 70%. Such large reductions in insect abundance suggest that insectivorous birds will suffer from food deficit, but also that reduction in the abundance of pollinating insects like bees, bumblebees and butterflies will reduce seed and fruit production. Many insects also kill other insects and hence play an important role in controlling the abundance of pests and for ecosystem functioning.


The following publications describing this method and some of the results can be downloaded from this web site:

Hallmann, C.A., Sorg, M., Jongejans, E., Siepel, H., Hofland, N., Schwan, H., Stenmans, W., Müller, A., Sumser, H., Hörren, T., Goulson, D. and de Kroon, H. (2017). More than 75 percent decline over 27 years in total flying insect biomass in protected areasPLoS One, 12 (10), e0185809.

Møller, A. P. 2013. Long-term trends in wind speed, insect abundance and ecology of an insectivorous bird. Ecosphere 4(1), article 6.

Møller, A. P. 2018. Long-term reductions in abundance of insects in Danish farmland and effects on insectivorous birds. Scientific Reports (submitted manuscript).