Cretan bluet (Coenagrion intermedium)
|Synonyms:||Coenagrion ponticum intermedium|
|Size||Length: 35 - 36 mm (2)|
Length of abdomen: 26 - 32 mm (2)
Hindwing: 19 - 24 mm (2) (3)
The Cretan bluet is classified as Vulnerable (VU) on the IUCN Red List (4).
The Cretan bluet (Coenagrion intermedium) is typical of the Coenagrion genus, commonly known as ‘northern bluets’, in which males possess vibrant blue-and-black colouration (5). Northern bluet females usually come in two colour forms, either sharing the male’s same blue-and-black colouration (known as homeochromatic morph), or being different, typically brown to olive-coloured (known as heterochromatic morph), and therefore easily distinguishable from the male (2). Known females of this restricted species are all heterochromatic and have the dorsal part of the abdomen largely black with a small blue-green area on the anterior part of each segment. They are easily distinguishable from the males, which are predominantly blue with black areas.
Found only in and around rivers, with Cretan bluet larvae having been collected from between floating tree roots (1).
Although not investigated, the larval period is thought to last around one year or less in the Cretan bluet, by extrapolation of what occurs in the closest relative species from the Mediterranean area. The flight period runs from the last third of April to mid-August. Adults feed on small flying insects. Males are unlikely to defend territories. Oviposition is done in tandem with the male. Females lay their eggs in floating herbs, small roots along the river edge and rotten wood in the water, using their ovipositor to cut a slit in the substrate (3).
The Cretan bluet is known from only 13 places spread over ten locations in Crete, and so is vulnerable to local agricultural policies, and the destruction of river bank vegetation destruction (4).
There are currently no conservation initiatives targeting the Cretan bluet.
Authenticated (18/12/2006) by Jean-Pierre Boudot, CNRS, Université Henri Poincaré Nancy I, France.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Larvae: stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
- Metamorphosis: an abrupt physical change from the larval to the adult form.
- Morph: one of two or more distinct types of a given species, often distinct colour forms, which occur in the same population at the same time (that is, are not geographical or seasonal variations).
- Ovipositor: egg-laying organ in female insects consisting of outgrowths of the abdomen (the hind region of the body in insects).
- Territory: an area occupied and defended by an animal, a pair of animals or a colony.
The Dragonflies of the Eastern Mediterranean (April, 2006)
- Dijkstra, K.D.B. and Lewington, R. (2006) Field Guide to the Dragonflies of Britain and Europe. British Wildlife Publishing, Gillingham.
- Jödicke, R. (2005) Bemerkungen zu Coenagrion intermedium (Odonata: Coenagrionidae). Libellula Supplement, 6: 15 - 24.
IUCN Red List (March, 2011)
Idaho Museum of Natural History (August, 2006)