Dragonflies:

Fantastic creatures and true aerial acrobats

The blue-winged damselfly is aptly named.

(Bild: ServusTV)

For many people, dragonflies are insects that are seen in passing. But these animals are a true marvel of nature. Unfortunately, their habitats are increasingly disappearing in Vorarlberg too.

Anyone who enjoys spending time by the water in summer will almost certainly have seen dragonflies performing their artistic flight maneuvers. They are true aerial acrobats, because thanks to their ability to move their pairs of wings independently of each other, they can change direction abruptly, stand still in the air and fly backwards. Some species can even reach top speeds of up to 50 km/h. Dragonflies are creatures of the air: everything that makes up their short life as adults, which only lasts a few weeks - hunting, feeding and mating - takes place in this element.

There are over 6000 different species worldwide, most of which are found in the tropics. Austria is home to 78 dragonfly species, 61 of which are native to Vorarlberg. "Our database contains a total of 7000 entries from Vorarlberg. The most frequently documented dragonfly species is the horseshoe damselfly, followed by the damselfly and the large damselfly," says biologist Werner Holzinger from ÖkoTeam Graz, who is considered one of the best dragonfly experts in the country.

The two pairs of wings enable spectacular maneuvers

(Bild: ServusTV)

In appearance and body structure, the animals living today resemble the species that lived during the heyday of the dinosaurs. Dragonflies are therefore very primitive insects and are quite spectacular to look at due to their usually striking coloration and huge eyes. The latter also achieve amazing things: with their compound eyes, dragonflies can detect almost the entire environment. As they can perceive ultraviolet radiation, the reflective water surface does not hinder the insects and they can even recognize underwater vegetation. Hundreds of impressions are processed within a few seconds, which enables the animals to react quickly during flight. This is because dragonflies are predators and feed on other insects that they catch in the air.

Dragonflies are children of the water
However, they begin their lives in the water. After the dragonfly larvae hatch from their eggs, they spend between a few months and up to five years there - depending on the species and the prevailing environmental conditions - as so-called lurking hunters. They feed mainly on insects, worms and tadpoles.

The miraculous dragonfly

How the dragonfly got its name: A French researcher in the 16th century discovered that the larvae of the small dragonfly look like a hammerhead shark. At the time, scientists gave it the Latin name "libella" (= spirit level) because of the shape of its head.

No danger to humans: Despite their considerable size, sometimes signal-like coloration and sting-like structures at the end of their abdomen, dragonflies are completely harmless to humans. They do not sting either. Only the females have "stingers", but these are used for laying eggs in plants and are not used for attacking.

How old is the insect order of dragonflies? The oldest dragonfly fossils to date come from Upper Carboniferous shale deposits and are around 325 million years old. Dragonflies are therefore among the oldest known flying insects.

The larvae have a clawed capture mask with which they can grab their prey at lightning speed. When at rest, the capture mask is folded under the head. A growing animal goes through between eleven and 15 larval stages. At the end, the larva crawls out of the water, anchors itself on a leaf, its shell breaks open and a dragonfly hatches out.

Dragonflies also suffer from habitat loss
After this, the insects have an average of between four and seven weeks left to reproduce. Dragonflies can be found in a wide variety of bodies of water. The richest in species are still waters such as ponds, pools and lakes, where the larvae live in the shallow shore zones and between aquatic plants. According to the state's environmental protection department, 28 different species have been identified on the shores of Lake Constance alone. However, this cannot hide the fact that the insects are increasingly losing their habitats, as Werner Holzinger reports: "Species such as the common damselfly and the southern damselfly used to be common on the Rhine, but are now unable to find a habitat as a result of the regulation of dead water."

Contrary to some preconceptions, dragonflies do not sting.

(Bild: Bergauer Rubina)

According to the expert, those dragonflies that have specialized in raised bogs are actually highly endangered. These include the large moss dragonfly and the helmeted damselfly, a particularly rare species that can no longer be found in other federal states. Renaturation of bodies of water and moors therefore not only has a positive impact on the climate, but also helps to preserve the dragonfly population, among other things. As the insects react quickly to environmental influences, dragonflies can also be used as bioindicators for assessing water quality. The worse the condition of a body of water is, the fewer dragonflies will circle above it.