Since moving to our new house two years ago I have been bitten every summer by what I have now identified as birch fly (aka blackfly). They were first heard of in Speyside a few years ago I believe, but no-one I've spoken to in my area has ever come across them. I have lived in this area in the west of Scotland since 1979 and have never had this problem. Midges and horsefly yes, but never blackfly. We live next to a small spate river where a small hydro scheme has just been completed earlier this year. Will this make a difference to numbers of these horrible little things? The generator shed and concrete outflow is about 100m away. I never feel them bite just find congealed trickles of blood or small subcutaneous haemorrhages around my ears and hairline mainly. The dog is a magnet for them. Next day the bites itch like mad and swell up and take days to disappear. I find taking a Loratidine tablet (once daily antihistamine, non drowsy) helps keep the itching and swelling to a minimum. Does anyone know of a repellent that works against these flies? I've tried all the usual including tropical strength mossie repellent but with no effect. Will be interested to hear any thoughts on this. Thanks
According to the paper by Crosskey, quoted in post Keys to blackflies, above, outbreaks of blackflies of species S. reptans and S. tuberosum have been happening in Speyside (particularily Kincraig) since the 1980s, and have been the subject of several studies. It is possible that the hydro scheme has stabilised the river flow so that it is more constant and flowing for longer periods, hence encouraging more breeding. A possible solution (which may be difficult to persuade the authorities to adopt) would be to close the sluices for 24 hours every week or 10 days to allow the stream to dry out and kill the larvae. There is also the larvicide route which could be controversial. In my personal experience, repellents are very short lived in effect. Only defence is to cover up and keep moving, and don't wear blue. Not much help, but there you are.