Today's blog post comes from one of two trainee ecologists in RSPB NI - Anne Guichard.
As a trainee ecologist with the RSPB, I have the chance to explore our natural world and learn about its wonderful creatures and the different ways we can manage habitats to help them. Our conservation work at Portmore Lough has led to 11 species of damselflies and dragonflies regularly breeding on the reserve ground. A single banded demoiselle was spotted there in July which hadn’t been recorded on site since 1996, and we are hoping for more species to breed on the reserve in the future. So before summer ends, I’d like to share with you some of the amazing things I’ve discovered recently about dragonflies and damselflies.
Brown hawker (Aeshna grandis) and emerald damselfly (Lestes sponsa) at Portmore Lough
A bit of background: Dragonflies and damselflies in Ireland
11 species of damselflies and 13 of dragonflies are resident in Ireland. They both belong to the order odonata (meaning ‘toothed jaw’ in ancient Greek) and were among the first flying insects to appear on earth. As some of the largest and most colourful insects in Ireland, the dragonflies and damselflies are easily identified in the field. They are carnivorous and can hunt prey whilst in flight.
Common hawker (Aeshna juncea) / Irish damselfly (Coenagrion lunulatum) at Montiaghs Moss
From water to air
Dragonflies and damselflies are usually seen near freshwater habitats like ponds, lakes or streams. This is because most of the life-cycle of odonate species is spent in water. The adults are relatively short-lived: two to four weeks for damselflies and around two months for dragonflies, but it can take from one year up to five years for the nymphs in the water to complete their development. Once this has happened, the nymphs will move to the shore and climb the stems and leaves of tall aquatic plants prior to emergence of the adult insect. If you have the chance to look closely at a pond frequented by dragonflies, you might find a very delicate nymphal cast called the exuvia. These are very useful indicators while surveying for dragonflies and damselflies. If you want to learn more about the life-cycle of aquatic invertebrates, I will refer you to the excellent blog here by fellow trainee ecologist Genevieve Dalley in RSPB Scotland.
Newly emerged four-spotted chasers, with the exuvia. In the bottom picture, it looks like it’s holding its case, and one of the wings still has to unfold.
Behaviour
I find the behaviour of dragonflies and damselflies fascinating to watch. It’s best on a warm sunny day which fortunately happened quite often this summer. It’s a very colourful show of blue and red damselflies flying among the vegetation while golden looking chasers are usually skimming low across the open water. Perched on the tips of emergent rushes and reeds, darter dragonflies are on the lookout to chase intruders of the same species as most male dragonflies are fiercely territorial. You can’t miss the sound of rustling of wings when they are in physical contact.
Top: Male common darter (Sympetrum striolatum) Bottom: Female black darter (Sympetrum danae)
Another great spectacle to watch is the egg laying process, especially when it happens under the water! I was lucky enough to see this recently on a trip to Peatlands Park. Two emerald damselflies walk backwards down an emergent stem to lay eggs until the female is completely submerged. The female at the bottom can trap a bubble of air between its wings so she can still breathe and remain under water for up to 30 minutes!
Emerald damselflies laying eggs underwater. You can see the female completely submerged in the bottom picture.
Some of our species of dragonflies and damselflies will still be on the wing until the end of September into early October, so get out there or you might have to wait another seven months for the show to be on air again!