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Category: Invertebrates
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Llanelli Naturalists Newsletter - January 2005 - No 71
Niel Mathew

One of the highlights for me this year was the long overdue sighting of the Club-tailed Dragonfly, Gomphus vulgatissimus, on the Tywi.  I had been looking for this beast nearly every year for the past dozen or more.  I had tended to look for it along the river below Dryslwyn Castle as this is where Ian Morgan came across it in 1990 or thereabouts.  So I suppose the long wait has been Ian’s fault!  Anyway, on one sunny May morning this year a small group, including some RSPB staff, met at the car park, to view the satisfactory arrangements made for Tree Sparrows here – nest-boxes, supplementary feeding, etc – before following the river down for some way, being mindful all the while that Gomphus may not be far away. We’d already had good views of some Tywi specialities such as Tree Sparrows, Little Ringed Plovers and, circling above us, a Hobby, when a small dragonfly was observed momentarily flying low over the water.  In the past this usually has turned out to be a banded demoiselle, a beautiful damselfly that tends to emerge at the same time as Gomphus and frequents the same sorts of places, i.e. stretches of muddy rather than gravely water.  On this occasion the mode of flight seemed quite different so we sat down on the bank to wait and watch.

It wasn’t long before it re-appeared, and with mounting excitement  I trained my binoculars on it, now feeling certain it was the eagerly anticipated insect.  It proved to be very obliging, since after flying towards the opposite bank it turned round, came back towards me and then promptly settled on my trouser leg to the delight and amazement of all!  It was really only while it is at rest that one can see properly the colours, mostly green and  black with yellow patches on the side of the “club tail” and  those diagnostic widely separated green eyes.   A good photo opportunity but, alas, no camera!  Known to be a fairly sluggish creature two were soon afterwards observed resting on the grass and one could approach quite closely.  In flight they are quite distinctive, generally low and circling above the water surface, seemingly colourless but with an individual and noticeable silhouette due to the “club tail”.  At least three were seen altogether, probably males sorting out their territories.  They would have spent some time since they emerged as adults away from the water, possibly much of the time in the canopy of trees, and then returned with their mature colours to hold territory and look for females.

There didn’t seem to be anything particularly special about this part of the river: there were pronounced meanders where the river flow is slowed allowing silt and mud to build up and areas of willow scrub that are probably important for shelter.  The flight season lasts only three weeks or so giving little opportunity to see it: other than this there are only the exuviae (the shells of the discarded larval form) to indicate that the species is present, but I’m not sure what these look like even though they are said to be distinctive! In closing I ought to say that if anyone is keen to see these insects they should make sure that they have the landowner’s permission. They are likely to occur at a number of spots along the river. This species is one of the notified features of the SSSI (the Tywi between Carmarthen and Llandovery) and we could do with more records.