Tuesday, August 20, 2013

Damselflies - Bluets & Bluetails

There are five groups of damselflies in Ireland. The reds, bluets, bluetails, spreadwings and demoiselles. Because of the amount of species this post will focus on the bluets and bluetails which are as the names suggest largely blue in colour.

Azure damselfly (Coenagrion puella) 
The azure damselfly is probably Ireland’s commonest damselfly species. It can be told from other bluets by the mark near the base of the thorax which forms the shape of a capital U. This marking is completely unconnected to other abdominal segments and is quite easy to spot once you are aware of it. The female has no such easy identification features and is so similar to other species that it is generally easier to just ignore them altogether and find a male. 

A female

Variable damselfly (Coenagrion pulchellum) 
This species is very closely related to the azure damselfly and from a distance looks practically identical. The main difference once again is the abdominal marking near the base of the abdomen. In variable males it forms a wineglass shape which connects to the next abdominal segment (look for the shape in the pics below). The female again is probably best ignored for identification purposes.

Common blue damselfly (Enallagma cyathigerum) 
This species looks similar to the Coenagrion bluets but is placed in a different genus. Like its name suggests, it is quite common, though not nearly as much as azure damselfly (in Cork anyway). Again males have a distinctive abdominal segment near the base of the abdomen which forms the shape of a rosebud. It also has broader stripes on the thorax and lacks the black spur marking underneath them that the Coenagrion bluets have.

Blue tailed damselfly (Ischnura elegans)
This is one of Ireland’s most common damselflies. Indeed I have encountered it in numerous different habitats such as Fota, Little island, Lee road, Blarney, Lee river etc. There are two species of bluetail in Ireland, both with a distinctive blue segment on a largely dark abdomen, the other species is quite similar and careful examination of the abdomen is required for identification. Just to confuse things further female blue tailed damselflies come in 5 different colour forms! Two are immature and therefore temporary whilst the other three are adult forms. Some of the below are guesses and I may be wrong on some as I am still learning… 

Violacea, the first immature female form, is described as having a violet thorax and violet tailspot. The tail on this specimen isn’t exactly violet but looks about right.
Rufescens, the second immature female form, is described as having a pink thorax and blue tail spot. This picture seems to match. They come in various shades of pink to red and some are quite vivid. My favourite.
Infuscans, one of the adult female forms, is described as having an olive green body and brown tail spot. This individual has more of a pink tail spot but I am guessing it is indeed an Infuscans.
Rufescens-obsoleta, the second adult female form, is described as having a brown thorax and brown tail spot. Almost certainly a match!
Typica, The fifth and final form is identical to the male. Indeed, I can’t tell typica and male apart. Both have blue (greenish) thorax and blue tail spot.
Scarce blue tailed damselfly (Ischnura pumilio) 
This is the other bluetail found in Ireland and as the name suggests is much harder to find. I didn’t think I would find this species in 2013 but to my delight I was wrong. Differences are quite subtle but the tail spot is closer to the tip and extends halfway up the segment next to it. It also has a tiny black mark in the blue of the tail spot.
I am delighted to have found all the species of bluet and bluetail present in Co.Cork. In fact the only one lacking from my list is the rare irish damselfly (Coenagrion lunulatum) which can’t be found in Cork. I hope to track it down next summer.

The list
Azure damselfly (seen) 
Variable damselfly (seen)
Irish damselfly
Common blue damselfly (seen) 
Blue tailed damselfly (seen) 
Scarce blue tailed damselfly (seen)

1 comment:

  1. What can I say? only absolutely gorgeous, I love this page guys.


Feedback always welcome