Friday, 21 April 2017

April 2017

The season is now well underway. Bee-flies have been seen regularly around the county. My earliest record was on the 29th March in Rothwell but Graham Warnes saw them the previous week in Northampton. In Northants we only have the one species of bee-fly, the dark-edged bee-fly Bombylius major.

Bombylius major  (c) John Showers

Two other species may yet occur in Northants. The spotted bee-fly Bombylius discolor is expanding its range northwards. It has a dotted pattern on the wings rather than the intense dark front edge of B. major.  The anthracite bee-fly Anthrax anthrax was found for the first time in Britain in Cambridgeshire last year. This latter species has been expanding its range in Europe and regularly visits bee hotels where it parasitizes the guests!

Although it is still rather cold, the dry and often sunny conditions at present create microclimates in sheltered areas and these are good places to find hoverflies, especially if there are nectar sources present. A walk round West Lodge Farm near Desborough on 19th April revealed 9 species of hoverfly. I managed to photograph a few and have attached the photos below together with the species distribution map up to the end of 2015 for Vice-county 32 - Northamptonshire and the Soke of Peterborough (historical Northants). The maps were supplied by Stuart Ball who jointly runs the UK Hoverfly Recording Scheme with Roger Morris. My thanks go to them for supply the maps and encouraging the study of hoverflies.
Rhingia campestris the Heineken Hoverfly on red campion (c) John Showers

(c) Stuart Ball



Cheilosia illustrata, a bumblebee mimic  (c) John Showers
(c) Stuart Ball


Epistrophe eligans, a typical Spring species of woodland edges (c) John Showers
(c) Stuart Ball


Eristalis pertinax, a common species whose rat-tailed larvae live in wet conditions (c) John Showers
(c) Stuart Ball


As you can see from the maps, these are widespread species. The gaps probably reflect lack of recording effort rather than real gaps in the distributions.

In addition to hoverflies I did find a number of other interesting flies:

The parasitic fly (Family - Tachinidae) Gymnochaeta viridis. A Spring species whose larvae parasitise grass stem-boring Noctuid moth caterpillars. (c) John Showers

The long-palped cranefly (Family - Tipulidae) Tipula varipennis. A common Spring species.
(c) John Showers










Monday, 13 March 2017

Norellia spinipes

Today I was looking for my first beeflies of the year on primroses but failed to find any. However I also looked at some clumps of naturalised daffodils on the roadside at Blatherwycke. The first few clumps had nothing on them but then one clump had six small, brown flies that I suspected were Norellia spinipes, a dung fly, Scathophagidae. These lay their eggs on daffodil leaves and the larvae mine the midrib of the leaf, leaving a characteristic pale line where they have been. I took one specimen home and confirmed its identity. A picture of the species can be found here:

More information is available on the British Scathophagidae Recording Scheme website here:

The species status is notable but that is likely to change as it seems to be increasing. It is probably an introduced species, coming in on imported bulbs. The first UK records were in 1965. 

I would be interested in hearing from others who have found it in Northants. It is fairly easy to identify, having the rounded head typical of a Scathophagid,  brown body with dark thoracic stripes; two rows of spines below the front femora and one row below the front tibia, giving a mantis-like appearance. It has dark shading over the cross veins and wing tip but this shading can be very feint. Look for it on daffodil leaves where daffodils are well established such as in parks, mature gardens and roadside verges.

Thursday, 16 February 2017

First hoverflies of year in Northants?

I received an email today from Lisa at the Wildlife Trust at Lings House, Northampton to say she had seen a marmalade hoverfly Episyrphus balteatus there. 

Coincidentally, I too saw my first hoverfly of the year today. It was a drone fly Eristalis tenax in Sane Copse, Yardley Chase. I am sure this mild spell will bring more out. Meliscaeva auricollis is another species that overwinters as an adult so can be found once we have some mild, sunny spells.

The winter months are the time to catch up with unidentified specimens from the previous season and I have been doing just that. Two less common species have turned up in the samples I looked at this week. One was a long-legged fly Dolichopodidae, found at Ditchford Lakes and Meadows in early July. The species was Poecilobothrus principalis. The closely related P. nobilitatus is a very common doli fly where the males display to the females on pondweed by flicking open their white-tipped dark wings and hopping from one side of the female to the other. P. principalis is much scarcer as can be seen from the NBN Gateway map - https://data.nbn.org.uk/Taxa/NBNSYS0000012641/Grid_Map
It seems to be a coastal species from the map but a number of primarily coastal species have been found in the Nene Valley.

The second uncommon species was the Scathophagid fly Cordilura aemula. Details of the species can be found on Stuart Ball's excellent Scathophagidae Recording Scheme website at  http://scathophagidae.myspecies.info/scathophagid-checklist/cordilura-aemula
This was found at Abington Meadows, Northampton in September. Its distribution is mapped here https://data.nbn.org.uk/Taxa/NBNSYS0000030370/Grid_Map

I still have quite a few flies to identify from last year so I am hoping to turn up some more interesting species.

Friday, 2 December 2016

Another new Cranefly for Northants

In mid-September I was sweeping under some willows next to a dried up pond in a former sand pit near Yardley Hastings when I took a small insignificant-looking cranefly. Back at home I keyed it out as a male Ormosia bicornis. On checking its distribution and status, I discovered that this is a Vulnerable (RDB2) species mainly recorded from calcareous woodland in Herefordshire. Its known distribution is shown on the NBN gateway:

As neither the location nor the habitat matched the literature, and with the scarce status of the species, I asked for a second opinion from John Kramer, who helps run the national cranefly recording scheme. John took the specimen and extracted and cleared the genitalia. He mounted the genitalia  on a slide and photographed them at the Natural History Museum in London. I have attached his photograph. It shows the characteristic twin spines on the styles that give it its "bicornis" name. These spines are at the top left and top right of the photo? The specimen now resides in the NHM's collection.

Photo by John Kramer, 2016

Saturday, 12 November 2016

Flies and Dead Wood

Many flies from a several families breed in various forms of dead wood. These microhabitats can range from the rotting sap under the bark of a felled tree, through rot holes in the trunk and larger branches or rot holes in the roots accessible at the base of a tree, to dead wood lying in streams or wet places. Added to this are the fungi that grow in these situations that provide habitat for other species. When a mature wood is clear-felled there can be a break in the continuity of these habitats. In natural woodland there is a range of tree ages from saplings to over-mature and dead trees. Many of our rarest flies are dependent on dead wood and, as most only have a short life-cycle, a population can be lost when woodland is cleared. Re-planting does not help as it will take maybe 50 plus years to start to develop the next population of dead wood, long after the dependent species have died out. Where new woods are established near ancient woodland, some people are trying to artificially create dead wood habitats through a variety of means. Some techniques are illustrated on the website of the Vetree project:
www.vetree.eu
See the link to training materials and look for the video on creating decaying wood habitats. It might be possible to emulate some of these techniques in the garden.

On the subject of dead wood, this year has thrown up some interesting records from felled poplar. During a Northants Diptera Group meeting at Pitsford Nature Reserve,  Kev Rowley swept Solva marginata (the Drab Wood-soldierfly) from near a felled poplar. This wood-soldierfly has been rarely reported in Northants, except in the far North-east of the county. Its larvae develop in the rotting sap of poplars that have been felled for about 1-2 years. This record shows that it is more widely spread in Northants than appears to be the case from the NBN Gateway https://data.nbn.org.uk/Taxa/NBNSYS0000007844/Grid_Map

Encouraged by Kev's find I investigated a poplar log pile in Sulby. I could not find any wood-soldierflies but did sweep a number of flies from the surrounding vegetation. When I  got round to examining my catch I found the lance fly Lonchaea hackmanni and the short-palped cranefly Gnophomyia viridipennis. Both of these species are associated with poplar and may be new to  the current Northants county.  (Vice-county 32 includes the former Northants area of the Soke of Peterborough).

Tuesday, 11 October 2016

New cranefly for Northants

On 5th October I was visiting Sulby Gardens, mainly to look for hoverflies. However, as I was walking alongside the shady stream I swept the vegetation. I took several common species of cranefly but one stood out as different because of its peculiar appendages on the last sternite. I keyed it out to be a male Tipula staegeri, subgenus Savtshenkia. The NBN gateway shows it as being widespread except in the Midlands. I sent a photo to John Kramer from the national Cranefly Recording Scheme and he confirmed its identity and that they had no records of it from Northants. It is an easy species to identify in the male because of the appendages on the last sternite, slightly mottled wings and a yellowish stigma. It is found alongside shady streams from late September to mid November.


Shropshire Craneflies

At first sight the title seems to be irrelevant to this blog. However, it is the title of a new book by Pete Boardman. Although it specifically covers Shropshire and only the craneflies found there, there is much of interest to anyone who wants to know our craneflies better. One of the features of the book is the use of a synoptic key rather than the usual dichotomous key. This involves looking at a list of features, each of which is assigned a letter. By noting the letters that apply to your specimen you look up a table of species with those features. The detailed species descriptions and close up photos should then be able to confirm your determination. As yet I have not yet tried the keys so cannot comment on their effectiveness. However I have successfully used the species descriptions and photographs to confirm identifications where the Cranefly Recording Scheme's keys left me with some doubt. The photos, which are annoted, definitely clarify interpretation of the drawings in the CRS key. 

The book contains a checklist of British genera, showing how many species there are in the UK and Shropshire and giving the latest names. There is also a checklist of species. I checked this against the Northants data and found one species from Northants that is not covered in the book. I intend to check that species is correct if I can find the voucher. Although there may be other species that occur in Northants but not in Shropshire, there is no doubt that the book will be very useful to cranefly enthusiasts in Northants.

I did notice a few minor errors but none that affected the usefulness of the book so I highly recommend it. An excellent piece of work.