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).