Since 1998, dragonflies have been counted bi-weekly on fixed routes as part of the National Dragonfly Monitoring Network. This allows for an annual average population index to be calculated based on 47 species. This enables tracking changes over time. The Netherlands has about 64 species of dragonflies; for the remaining seventeen species, there is insufficient reliable data available to use for the population index.

Cold-loving species, such as the green hawker and the northern winter damsel, have decreased by about 75% since the start of the measurements, averaging 5% per year. Some species, such as the lunar water damsel and the northern white-faced darter, have declined by more than 95% in the last twelve years.

Heat-loving species, such as the fire dragonfly and the southern emperor dragonfly, are increasing as a group by an average of 5% per year, although the growth has slightly leveled off in recent years.

Also, common species are declining: the 15 most common dragonflies of the Netherlands, including the damselfly and the horse-biter, have decreased by an average of 15% since 1999. This decline is probably not explained by the temperature preference of these species, as these common species are generally more heat-loving than cold-loving.

Besides dragonflies that occur in almost all types of water (such as the damselfly), some dragonflies are specialists of certain habitats. Dragonflies from fens and raised bogs, such as the spear water damsel and the fen hawker, have been declining since 2010. Climate warming and drying play an important role here: in warm summers, the water in fens and raised bogs can warm up significantly, leading to heat stress among the dragonflies in this group (including more cold-loving than heat-loving species).

Fens also dry out more often under such conditions, making it impossible for dragonflies to reproduce and causing populations to disappear locally. The dragonfly population of fens and raised bogs decreased sharply after the dry summers of 2018 and 2019, with no recovery following.

Dragonflies from lowland peat and marshes, such as the spotted white-faced darter, initially increased but have decreased by over 20% since 2018. However, the numbers of dragonflies in this habitat are still slightly above those of 1999. Dragonflies from flowing water, such as the beautiful demoiselle, have increased by 43% over the entire period.

Sources

• Compendium for the Environment – Trend of Dragonflies, 1850-2023
• Website - National Dragonfly Monitoring Network