In response to the letter by Colin Jacobs in White Admiral 41 'Common Darter Egg Laying in Puddles' I offer the following observations. Firstly, I have also seen this species ovipositing in puddles on two or three occasions over the last few years. This was always whilst I was doing general surveying of aquatic invertebrates and all locations were close to rivers, namely the Lark and Stour.
On another occasion, at Bradfield Woods, (TL 933575) in August 1997, I saw one pair of Sympetrum striolatum actually egg laying on a wooden sleeper making up part of the track. The sleeper was very shiny and reflecting the sunlight. I'm sure, although I can't locate the reference, that the polarisation of reflected sunlight may be one factor in stimulating egg laying at a particular site. The puddles and sleepers may have approximated to the water surface of a river or pond in this respect.
My final observation, and to my mind the most memorable, was an underwater sighting of Sympetrum in Ibiza some years ago. Next to the beach was an area of swamp and freshwater ponds, where many Sympetrum were ovipositing. On this particular occasion I had been snorkelling in the sea and surfaced to find my head surrounded by egg laying dragonflies. I presume an off shore breeze had drifted them out to sea. The eggs would have certainly died but the dragonflies seemed oblivious to the change in the water quality. By submerging I was able to see the females' abdomens dip into the calm sea surface and release eggs. I am not acquainted with the dragonfly species of that area but they certainly appeared to me to be identical to the English S. striolatum.
Adrian Chalkley Aquatic Invertebrate Recorder
With reference to Harry Barnett's interesting article on Redgrave and Lopham Fens in White Admiral 41, I would like to point out that the work by David Bellamy that he refers to on page 6 was in fact done by David Bellamy and Francis Rose.
Members who are interested should refer to:
Bellamy, D.J. and Rose, F. (1960). The Waveney-Ouse Valley Fens of the Suffolk - Norfolk Border. Trans. Suff. Nat. Soc. 11: 367-385. (Ed).
David Strauss
In the summer of 1998 someone sent to retrieve the irrigation pipes from the top of the Brussels sprout field at Alder Carr Farm came back and reported that he had not been able to do the job because of the wasp nest. Indeed there was a large hole in the bank - probably an old mouse hole, with the typically trimmed lawn of grass round the entrance and a steady stream of wasps buzzing in and out, quite unconcerned by our presence. On one of our regular crop walks to inspect pest levels, we noted a marked absence of caterpillars and aphids in the sprouts and remarked that we had sprayed the crop against pests only once (with wasp-friendly chemicals - details available on request!). We usually have to do this more than once or the plants become reduced to lacy shreds and smothered in aphid honeydew, which subsequently grows sooty mould; not to mention whitefly which can gather in clouds. The inevitable conclusion was that the wasps had cleaned them all up to feed their growing brood. Is there any future in wasps as biological controls? Cultivated bumble bees are already used widely for greenhouse pollination - could wasps be used for pest control or would the practicalities be too painful? I think any research into this subject might also be too painful! Though it might be possible just to sit near the nest and see what was brought in - any takers?
Joan Hardingham, Alder Carr Farm, Needham Market.