Boyeria irene
Boyeria irene (Fonscolombe, 1838)
Local names: Western spectre, Westliche Geisterlibelle, Schemerlibel
Species Information
Description
Boyeria irene is unmistakeable for its large size and the camouflage colouration; grey green with brown patterns. The males and rarely the females have darkened wing tips. The eyes in immature individuals are green. The frons is yellow with an indistinct black pattern.
Size
Habitat
Boyeria irene is found on larger streams and rivers where the banks are at least partly shaded. In north-western Spain and northern Portugal it is also common at small streams, even those experiencing interrupted flow, due to summer drought. In Switzerland and French alps it reproduces in large lakes between 400 and 800 m in altitude, where wave commotions produces similar effects to those of running waters. These lakes are deep and sometimes have rocky or steep man-made banks with little vegetation. The species is mainly found in lowlands and hilly countries but has been found breeding up to 1 300 m in the southern Alps of France.
Distribution
Endemic to western Europe, Morocco and along the northern fringe of Algeria and Tunisia. The species is widespread and common across most of the Iberian peninsula and southern France, becoming progressively scarcer in the north where its range goes up to Brittany, Normandy, Champagne-Ardenne and north-east France. In Italy, it is largely confined to the western parts of the country, where it is generally uncommon. The species is reasonably common in Corsica and Sardinia. It is absent from the Balearic islands. In Switzerland it is found in the south and centre. Vagrants have been recorded in south Germany.
Flight Period
June to September
Behavior
It is a powerful and untiring flier, capable of flying for long periods without perching. It prefers shady areas and often flies late in the afternoon, so much it is considered a dusk species. It has twilight habits and can be found attracted to artificial lights.
Conservation Status
Similar Species
Boyerina cretensis
External Links
Genus: Boyeria
Boyeria is a genus of dragonfly in the family Aeshnidae, commonly called spotted darners. The name Boyeria commemorates the French entymologist Etienne Laurent Joseph Hippolyte Boyer de Fonscolombe.
Identification
Boyeria is not a colourfull genus, rather they are somewhat dull and blotchy, like military camouflage. Most males and some females have wings with darker tips (especially the hindwing). Pterostigma are moderately long, covering 4-7 cells below it.
Separation from other genera
In the field it is important to observe habitat, behaviour and colour. In the hand hand wing venation can rule out any confusion. Caliaeschna has similar habits, but their ranges does not overlap. Caliaeschna also are much smaller, with more contrasting markings and has a short pterostigma. Most Aeshna species have more conspicuous markings. Both Caliaeschna and Aeshna species never have dark wing tips.
Separation of the species
Boyeria is a genus with isolated relict populations. It contains two species in eastern North America and three in eastern Asia. Two species are endemic to Europe.
Behaviour
Males patrols long routes, slowly flying low over the water. They tend to keep in the shade along the edge of the water and often stop mid-air to inspect dark corners, e.g. under tree roots. They avoid sunlight (still they tend to stop patrolling when the sun is clouded). They become more active towards the late afternoon and aggregate at dusk when they hunt in fast, zig-zagging flight over clearings. They remain on the wing until nightfall and may be attracted to light thereafter. The behaviour of B. cretensis is poorly known. Males are said to patrol fast over streams in the afternoon, passing low between rocks.
Family: Aeshnidae
The Aeshnidae, also called aeshnids, hawkers, or darners, is a family of dragonflies. The family includes the largest dragonflies found in Europe and North America and among the largest dragonflies on the planet.
Description
Common worldwide or nearly worldwide. Genera are Aeshna and Anax. The African Anax tristis has a wingspan over 125 mm, making it one of the world's largest known dragonflies. Most European species belong to Aeshna. Their American name darner stems from the female abdomens looking like a sewing needle, as they cut into plant stem when they lay their eggs.
The dragonflies mate in flight. The eggs are deposited in water or close by. The larvae (nymphs or naiads) are generally slender compared to those of other families, with a long and flat extensible lower lip (labium). The larvae are aquatic predators, feeding on other insects and even small fish.
The adults spend large amounts of time in the air and seem to fly tirelessly. They can fly forwards or backwards or hover like a helicopter. The wings are always extended horizontally.
The abdomen are mostly colored blue and or green, with black and occasionally yellow. The large, hemispherical, compound eyes touch in the midline. Individuals of this family have an extremely good sight, and are voracious insect predators.
A proposal has been made to split this family into Aeshnidae and Telephlebiidae.
The name may have resulted from a printer's error in spelling the Greek Aechma, a spear. The spelling Aeschnidae has been intermittently used over a period of time, but is now abandoned for the original name Aeshnidae. However, derived genus names (such as Rhionaeschna) retain the 'sch' spelling, as this is how they were first cited.