 |
|
Hairy Dragonfly: a new breeding species
On the weekend of the 24th/25th April 2004 Graham Wearne noticed a total of six dragonfly exuvia floating on the surface of his suburban garden pond in Oadby, just south of Leicester. Although snails had started to consume a number of the exuviae he rescued the two most intact specimens and saved them for future identification. He also noted a further two larvae of the same species close to the pond’s surface amongst submerged vegetation. Unaware of the potential significance of his find Graham put the exuvia in a film canister and posted them to my home address, along with a note explaining the circumstances of his discovery [I offer an exuvia identification service - see the foot of the page]. When I opened the pot a couple of mornings later I nearly choked on my cornflakes, as it was immediately apparent that they were Hairy Dragonfly exuvia. The larval cases of this species are relatively easy to identify, having a particularly distinctive head shape, and the time of emergences immediately eliminates all other Aeshnid species. Having been made aware of the significance of the find Graham continued to check the pond for exuvia and found a total of approximately twenty-five between 24th April and 16th May 2004. The record is of particular significance for a number of reasons. Firstly, it is the first ever proven breeding record of the species in VC 55. Although ovipositing has been observed at the Grantham Canal and breeding suspected at another private site in the north east of the County, the all-important proof of completion of the life cycle has until now been lacking. The date of the emergence is another particularly interesting factor, for a species whose flight period is normally quoted as commencing in early to mid May. On the subject of the emergence date, however, Adrian Parr of the British Dragonfly Society has commented as follows: “I wouldn’t be too worried about the date; although it’s the earliest for the species that I’ve heard of so far this year, there have been a number of earlier records in recent years. Also, my experience is that garden ponds can often give rise to early Aeshnid records - I guess the shallow water warms up readily, and suburban settings tend to be a few degrees warmer than the countryside anyway”. Finally, the garden pond setting is highly unusual and possibly the biggest surprise. Graham’s pond measures a mere six feet by eleven feet in area. It is a great distance from the nearest large body of water which would be considered a suitable breeding site for Hairy Dragonfly and it can only be assumed that a wandering gravid female may have been desperate on finding no suitable habitat, and simply oviposited in the nearest remotely suitable water. No foreign material has been imported to the pond for many years so there is no chance that the larvae may have been inadvertently introduced. Images of one of the larvae plus those of a Southern Hawker are shown for comparison.
I would like to conclude by congratulating Graham, a relative newcomer to dragonfly study, on his observational prowess to initially spot the small floating specimens and also for his presence of mind to forward them for identification. Hopefully this fantastic record will spur on other observers to follow in his footsteps and maybe also construct a garden pond? Exuvia IdentificationWith the help of John Wright and his microscope I seem to be making some inroads into the fascinating field of exuvia identification. I cannot stress enough how important it is to produce proof of breeding at a site and I urge you all to go out and search for exuvia. |
|