As part of the LIFE IP IRIS Project, measures to improve flood protection and ecological quality are being carried out on various rivers throughout Austria. To evaluate the effects of these measures, different indicators are selected. These indicators are then analyzed before and after the implementation of the measures, and subsequently compared with each other.

Bioindicators are organisms, such as fish, crayfish, and insects (larvae), that inhabit specific ecological niches. Field observations of these organisms provide insights into the ecological condition of the water. Biological monitoring is a bit like detective work!

In the LIFE IP IRIS Project, dragonflies are also considered as bioindicators. Dragonflies start their lives as larvae in the water before emerging as adults (mature insects) taking flight. They inhabit specific ecological niches and respond sensitively and precisely to localized changes. Together with other indicators, they provide informative data during pre- and post-monitoring stages, offering insights into the changes resulting from the LIFE IRIS measures.

We would like to introduce you to these fascinating creatures and have compiled 10 fascinating dragonfly facts for you.

Dragonflies are umbrella species. By protecting dragonflies and their diverse habitats, many other aquatic species benefit!

Each species has its ecological niche – both larvae and adults have preferences:

Some species are almost always in the air. Others can often be observed basking in the shore area, often aligning their abdomen precisely towards the sun (obelisk posture) to protect themselves from overheating.

There are dragonfly larvae that require sandy substrate underwater, where they bury themselves as skilled ambush predators, with only their heads exposed.

While some dragonfly species shimmer in the sun, others have mastered the art of camouflage.

Did you know that males and females of the same dragonfly species can have completely different colors?
For instance, the females of the dazzling jewel dragonflies are quite inconspicuously brownish-green.

Their adaptations, however, make them excellent hunters for their prey: smaller insects like mosquitoes or flies.

Dragonflies possess a capturing mask, both as larvae and as adults, which they can unfold rapidly to capture their food.

Later, these skillful flyers even capture their prey using their legs directly in mid-air.

Because dragonflies occupy such specific ecological niches, they can serve as bioindicators, providing insights into their habitat. Some dragonfly species exclusively inhabit stagnant waters, while others specialize in flowing water. Factors such as river morphology, flow rate, shoreline vegetation, and water quality, for example, influence the occurrence of individual species. Through a dragonfly-related study, one can learn a lot about the inhabited bodies of water in reverse. It’s detective work in action.

Dragonflies form a tandem during mating.
Mating is successful only within the same species, following a key-lock principle. The male attempts to ensure his own paternity through a variety of strategies.

Throughout the year, you can find different dragonfly species at bodies of water. Some appear in the spring and early summer, while others can still be seen flying into the autumn.

And then there’s the winter dragonfly: it’s the only species that overwinters as an adult. It has a kind of antifreeze in its ‘blood’ (hemolymph) to survive the cold.

Approximately 300 million years ago, at the end of the Carboniferous period, there were dragonfly-like insects that had wingspans of up to 70 cm. These giant dragonflies were already in existence BEFORE land-dwelling dinosaurs roamed the Earth.

Currently, there are 78 dragonfly species in Austria, showcasing an extraordinary range of colors and shapes. Worldwide, there are approximately ~6,500 different dragonfly species!

Dragonflies also exhibit various colorations throughout their life cycle.

The yellow-black damselflies spend about 5 years as larvae underwater before taking flight as adults for a summer. Unlike butterflies and similar insects, they do not pupate: the final larval stage leaves the water for the last molt.

Willow emeralds lay their eggs in tree bark. From there, the hatched larval stages sometimes have to travel a dry distance back to the water – not so easy without legs.

While in Europe, dragonflies were sometimes associated with misfortune as ‘devil’s darning needles’ and ‘eye-pokers,’ they have been a symbol of luck in Japan. One historical name in Japan was ‘Akitsu shima,’ which means ‘Island of Dragonflies.’

In English as well, dragonflies have a fairy-tale quality: ‘dragonfly.’