For the large dragonfly (Cordulegaster heros) and other representatives of the dragonfly family (Cordulegastridae), it is characteristic that their large eyes touch each other only at a single point. The large dragonfly is certainly one of our largest dragonflies, as it is usually about 77 to 84 mm long, and its wingspan is around 9.5 cm.
The male and female are similarly colored. Black is the dominant color of the body, interrupted by a pattern of vivid yellow spots. The yellow spots, like rings, surround the abdomen and meet on the dorsal side. On each abdominal segment there is one such ring. If we view the large dragonfly from above, we notice that at the terminal part of each of the first four abdominal segments there are two narrow yellow stripes. For this species, the shape of the paired yellow stripe on the dorsum of the thorax (antehumeral stripe) is also characteristic; the upper outer edge of this stripe is angular in the large dragonfly.
The large dragonfly is visually extremely similar to and only slightly smaller is the torrent dragonfly (Cordulegaster bidentata), therefore we must be careful when identifying our two specimens from the genus Cordulegaster.
The large dragonfly inhabits forest streams, especially at the transition between lowlands and mid-mountains. The large larvae of this species also spend several years in parts of the stream, where the bottom is covered with sand or gravel, on which a thin layer of fine organic debris has settled.
This is a summer species that in the adult stage does not appear before June, after which we can admire these magnificent dragonflies all the way to August.
The large dragonfly is listed in the Slovenian Red List in the category Vulnerable species (V). In addition, it is on the Natura 2000 list of species, which actually means that it has been recognized in Europe as a 'guardian' of biodiversity. Its presence, indeed, indicates the good conservation of forest ecosystems and their natural functioning.
