Dark spreadwing  (Lestes macrostigma)

The dark spreadwing has not yet been globally assessed, but is classified as Near Threatened (NT) on the IUCN Mediterranean Red List (1).

A relatively large species of damselfly, the dark spreadwing (Lestes macrostigma) is named for its habit of resting with its wings spread out, rather than closed as in most other species of damselfly (3) (4). It is a dark-bodied species with powdery-blue markings on both the male and the female (2) (3). The pterostigmas (the dark coloured cells near the tip of the wings) of the dark spreadwing are large and black, covering two to four cells on both the fore and hindwing (2) (3).

Although there is little information on the specific appearance of the dark spreadwing larva, damselfly larvae in general are slender with three long, tail-like appendages at the end of the abdomen, which are actually external gills (4).

The dark spreadwing occurs in small, scattered populations in southern and central Europe and parts of Asia, with its main European distribution located in the Mediterranean area (3) (2). From west to east, the dark spreadwing can be found from the Atlantic coast in France, to central Asia and the Middle East (2).

The preferred habitat of the dark spreadwing is shallow, stagnant and often brackish water, sometimes in large, temporary pools or marshes (2) (3).

While there is little specific information available on the biology of the dark spreadwing, it is likely to have aspects in common with other damselfly species. Damselflies have a complex lifecycle which includes a fully aquatic larval stage (4). As larvae or ‘nymphs’, damselflies are effective predators with the fascinating feature of being able to fire out the lower portion of the mouth, known as the ‘mask’, in order to grasp passing prey (4) (5). As well as being able to walk, damselfly larvae are able to move through the water by swimming, using a side-to-side motion of the abdomen and tail-like appendages (4).

The total length of time spent in the larval stage varies between damselfly species, with some species spending a few months and others several years as a larva (4). The larva undergoes several moults before finally emerging from the water as the readily recognisable adult damselfly (4). The flight season of the adult dark spreadwing varies depending on the location, but is generally from around May to August (2).

Reproduction in damselflies generally involves very little courtship behaviour, and begins with the male grasping the female by the back of the neck with claspers at the tip of the abdomen (4). Mating then takes place in the air, on the ground or among vegetation, with the length of the process varying greatly between species (4). In most species of damselfly, the male will then remain attached to the female during egg-laying (4). The female dark spreadwing lays the eggs inside the stems of water plants, with a preference for the cosmopolitan bulrush (Bolboschoenus maritimus). The eggs then overwinter before hatching during the following spring (2).

Damselflies are skilled aerial predators, typically feeding on small insects caught on the wing (4) (5). They usually hunt from a perch, darting out to pursue prey once sighted before returning to the perch to consume it (4).

Approximately 15 percent of dragonfly and damselfly species in Europe are currently considered to be threatened with extinction (8). The main threat to many species is the drying out of their freshwater habitat as a result of warmer, drier weather and unsustainable extraction of water for drinking water and irrigation (8). Pollution and the construction of dams and reservoirs are also impacting some populations (8).

Climate change is also expected to impact many dragonfly and damselfly species in the future, increasing the level of drying in some freshwater habitats and also causing species’ ranges to shift northward, potentially causing a decrease in the amount of available habitat (8).

In addition to these threats, the dark spreadwing is also currently faced with a number of other threats to its habitat including industrialisation, urbanisation and tourism (2).

While the dark spreadwing is known to occur in two protected areas in France, further measures are required in order to protect the scattered populations of this species (2). Future monitoring of its populations will provide valuable information on changes in the abundance of this species, as well as providing important information on its biology (2).

The dark spreadwing may also benefit from general plans to conserve dragonfly and damselfly species across Europe, including better management of freshwater habitats and developing a network of volunteers and experts to monitor changes in dragonfly and demselfly populations (6).

Find out more about the dark spreadwing and other threatened damselfly pecies:

• Kalkman, V.J. et al. (2010) European Red List of Dragonflies. Publications Office of the European Union, Luxembourg: Available at:
  http://ec.europa.eu/environment/nature/conservation/species/redlist/downloads/European_dragonflies.pdf

Find out more about species in the Mediterranean Basin:

• ARKive - Mediterranean Basin:
  http://www.arkive.org/eco-regions/mediterranean-basin/