Before I was driven off by a heavy shower I noted some flowering ivy, always a good nectar source at this time of year. Two attractive hoverflies were visiting the flowers - Myathropa florea and Volucella zonaria. The latter is our largest hoverfly and has the common name of hornet hoverfly because of its close resemblance to and association with hornets. It only arrived in Northants in the mid 2000's but is now reported quite frequently, especially from gardens growing Buddleja.
Volucella zonaria Pitsford Water 15/9/2017
Distribution of Volucella zonaria in Northants by end of 2015.
Map kindly supplied by Stuart Ball of the UK Hoverfly Recording Scheme.
Whilst at Pitsford I examined the trunks of poplars, especially those that had been felled, looking for flies associated with rotting sap. I did not find any on the trunks but sweeping adjacent foliage produced two specimens of the cranefly Gnophomyia viridipennis. The larvae of this fly live in the sap layer and especially favour poplar. The adult is distinctive as it is one of the few all black craneflies and has bright yellow halters. There were no records in modern Northants up to last year, although it had been recorded in the Peterborough area of Vice-county 32, the historical area of Northants. I found it last year at a log pile in Sulby and had found it on the Holcot Bay poplar log earlier this year. So yesterday's find was the third county record.
Gnophomyia viridipennis on a Sycamore leaf, Pitsford Water, 15/9/2017
The UK distribution map can be found on the NBN Atlas here: https://species.nbnatlas.org/species/NBNSYS0000008180