The azure hawker (''Aeshna caerulea'') is one of the smaller species of hawker

dragonflies A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of dragonflies are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threate ...

, (family

Aeshnidae Aeshnidae, also called aeshnids, hawkers, or darners, is a family of dragonflies, found nearly worldwide, with more than 50 genera and over 450 species. The family includes some of the largest dragonflies. Description Common worldwide or nearl ...

). The flight period is from late May to August It is about 62 mm long. Both sexes have azure blue spots on each abdominal segment and the thorax also has azure markings. The markings on the male are brighter and more conspicuous than in the female. The female also has a brown colour form. This species flies in sunshine, but will also frequently bask on stones or tree trunks. By lowering their wings during basking, they are able to increase the temperature of their bodies by as much as 7C compared to air temperature and continue searching for mates. It shelters in heather or similar low vegetation in dull weather. Possibly similar to '' Austrolestes annulosus'' and '' Diphlebia nymphoides,'' the abdominal and eye spots of males reversibly change from purple-gray pales as temperatures decrease to more bluish as they increase. The species is widespread in the

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

polar region The polar regions, also called the frigid zones or polar zones, of Earth are Earth's polar ice caps, the regions of the planet that surround its geographical poles (the North and South Poles), lying within the polar circles. These high latitu ...

and the

Alps The Alps () are some of the highest and most extensive mountain ranges in Europe, stretching approximately across eight Alpine countries (from west to east): Monaco, France, Switzerland, Italy, Liechtenstein, Germany, Austria and Slovenia. ...

in Central Europe, leading to the conclusion that the species is a

glacial relict A glacial relict is a population of a species that was common in the Northern Hemisphere prior to the onset of glaciation in the late Tertiary that was forced by climate change to retreat into refugia when continental ice sheets advanced. They ar ...

. However, larvae are restricted to micro-climates with very consistent, warm water with

peaty Adam George Peaty (born 28 December 1994) is an English competitive swimmer who specialises in the sprint breaststroke events. He won the gold medal in the 100 metre breaststroke at the 2016 Summer Olympics, the first by a male British swimmer i ...

bottoms. Adults frequently feed upon '' Boloria aquilonaris'', ''Inachis io'', ''

Erebia ''Erebia'' is a Holarctic genus of brush-footed butterflies, family (biology), family Nymphalidae. Most of the about 90–100 species (see also #Taxonomy and systematics, below) are dark brown or black in color, with reddish-brown to orang ...

'', and '' Phytometra gamma'' which are more common in the bogs of the Alps than surrounding habitats..

References

External links

British Insects: Odonata
Aeshnidae Dragonflies of Europe Insects described in 1783 Taxa named by Hans Strøm {{Aeshnidae-stub