DRAGONFLIES IN 2002

Mike Averill

Following the restrictions in 2001, this year was welcomed as an opportunity to get out in the field again. The long term study on the Club-tailed Dragonfly at Bewdley had to be suspended last year but its resumption in 2002 proved worrying with the lowest counts of emergence recorded since the study began in 1987. The reason for this is uncertain but it may be due to the succession of dull June months in recent years. June is the time when the Club-tailed Dragonflies are most active and during this synchronised period good weather is needed for mating.

There have been reports of possible reduced damselfly numbers at sites this year, but this is difficult to prove and it may only be that there has been a lack of favourable viewing weather.

Attention has again been focused on migrant dragonflies this year when the Red-veined Darter arrived for only the second time in Worcestershire. The first sightings were on 1st June when two males were spotted at Ryall gravel pit with a further two males at Kinsham gravel pit, but the most numbers were found at Pirton where 12 individuals were seen. There was also a sighting at Grimley Gravel Pit, but Pirton for some reason proved to be the hot spot with up to 50 individuals being seen later in the same month. Red-veined Darters have been seen before in the county and the question of whether these small influxes can breed successfully is always raised. This year the question was answered when on the 22nd September when seven exuviae were readily found at the margins of Pirton Pool. There was no sign of the adults though and the prospect for them is not good with winter weather approaching, however it can only be hoped that the adults were able to complete their cycle by egg laying. It was interesting that Worcestershire had probably the largest influx of migrant Red-veined Darters in the country because this sort of invasion is usually marked by synchronised influxes in coastal locations.

It would perhaps be interesting to see how easy this dragonfly is to identify in the larval form and it is in fact one of the easiest Darters of all. Once the individuals has been keyed out to one of the Libellulidae (spoon shaped labial mask and cerci less than half the length of the paraprocts), then it is separated from other members of the Libellula or Orthetrum genera by having long hind legs and a tapering area to the rear of the head. At this point it becomes clear that it is the only Sympetrum with no dorsal spines on the abdomen. If this darter does succeed in emerging next year it will be in early June, so please be on the look out.

Pictures from
Gardner A E 1954 A key to the larvae of the British Odonata . Entomologists Gazette 1954, 5:157-171,193-213, with additions to the Sympetrum key, 1955, 6:94-95