On account of the lovely weather in October there were lots of Common Darter dragonflies on the wing during the month. Around the entrance gate at McGlincheys is a favorite hang out for them. Away from water they are not so territorial and lots of males and females bask alongside each other on the track. There is always some perching on the wooden gate waiting to pursue any prey that flies by. The adults emergence peak is in late summer but they can emerge any time between June and October inclusive.
Common Darter Sympetrum striolatum is the commonest dragonfly in Ireland. Several years ago Ireland’s expert on dragonflies, Brian Nelson, gave a talk in McGlincheys and he estimated that Sheskinmore had the biggest population of Common Darter in Ireland. Eighteen of Ireland’s 24 Odonata species have been recorded in Donegal. Brian has identified 15 species of Dragonflies and Damselflies Odonata from Sheskinmore and considers it to be the most species rich site in the county.
Dragonflies and damselflies are colourful, predatory insects of freshwater habitats. They are characterised by their elongated bodies, long wings and large eyes. The male Common Darter is bright red and the female and immature adults are yellow-brown. Their abdomen is not waisted and there is a pale stripe on their legs, which you won’t see in the field but can see in a photograph.
Unlike butterflies, dragonflies do not have a pupal stage and progress to adult through a final moult that takes place out of water. The larva attaches itself to vegetation and the adult then breaks slowly through its larval skin. The adults life expectancy is short, typically a few weeks. Most of the dragonflies life is spent in its larval stages in water. The larvae may spend more then a year transitioning through up to 15 moults before it finally emerges as an adult.
The appearance and habits of each species have evolved so that they can occupy different niches and avoid competition and predation. The best larval habitats have varied aquatic flora and are mainly unshaded, unpolluted permanent water with an absence of predatory fish. The dune slacks and the shallow loughs at Sheskinmore are perfect examples of ideal larval habitat. Odonates are valuable indicators of the health of freshwater habitats.
The Dragonfly Ireland dataset is available online on the National Biodiversity Data Centre website. They have also produced a handy field ‘swatch’ that is a pocket sized guide to Ireland’s dragonflies.