Wednesday, 5 December 2018

Spring 2018

I apologise for not posting anything here for some time. Very remiss of me. After a cold and wet start to the Spring we moved into a period of warm weather before things started to get very warm and dry. Generally British flies like mild dampish conditions and do not cope well in either the cold and wet or in prolonged hot, dry conditions so this year has been a mixed bag from a recording point of view.

The warm weather in May and June did produce a large emergence of our local comb-horned craneflies Dictenidia bimaculata and Ctenophora pectinicornis. In most years I get one or two records of these species at best but this Spring I had records from new sites and a very large emergence at Yardley Chase. They have the common name "comb-horned" as the males have antennae which bear two rows of branches, like the teeth of combs. The cranefly larvae live in rotting wood in mature trees, often high up in branches. The adults are occasionally seen near the ground after emergence. The comb-horned antennae are thought to be an adaptation to allow the males to find females by detecting their pheromones. In the tree canopy sensitive detectors would be needed to find a mate.

The reason for the sudden increase in records is probably down to the tendency for these insects to emerge in warm conditions.

Dictenidia bimaculata male showing the "comb-horned" antennae

Ctenophora pectinicornis female. This mimics a wasp but the projecting spike at the end of the abdomen is harmless. It is the ovipositor for laying eggs.

Neither species is very common. They are best looked for near ancient trees with rotten branches in woods or parks on warm days in late May and June. They often rest on tree trunks or nearby vegetation. Photos of them with details of location and date would help us find more sites for them. There are a few other comb-horned craneflies in Britain, some are extremely rare, so do try to photograph any you may come across. Photos can be posted on the Facebook WILDside Project Group.

Sunday, 8 April 2018

Diptera Identification Workshops

There are two workshops coming up that may be of interest to dipterists.

On Saturday, 12th May, John and Barbara Ismay and Jann Billker hold an Acalyptrate Clinic in the Collections area of the Oxford University Museum of Natural History. It is from 10 am to late afternoon. They will help you with the identification of Acalyptrata families (Diptera)  to family level and many of these to genus or species. Please bring a few specimens that you find difficult or would like confirmed. The clinic is restricted to a maximum of 8 participants, so please let John and Barbara Ismay ( ) know if you would like to come. It would also be useful if you could let them know which families you are interested in. They will also bring some draft keys to smaller families that you could use.

I shall be holding a workshop at Pitsford Water on Sunday 22nd April. This will consist of identification of pre-pinned specimens and some field work. The balance will depend on the weather and attendees preferences. This is part of the WILDside project and attendees should contact Ryan Clark at the Northants Biodiversity Records Centre to book a place. The aim is to provide people who have already attended a fly identification workshop some practice as the season gets started.

Saturday, 16 September 2017

Mid September 2017

The cool, wet weather of late has not been great for fly hunting. However, there seems to be more fungi about in the woods and this could be good for those flies that breed in the fruiting bodies of fungi.  There are several families of flies that do this and some are fairly elusive as adults. Platypezidae is a family that I hardly ever come across so I will be looking out for these over the next few weeks. One way of finding them is to collect some fungus and keep it in a box with ventilation and see what emerges. Apart from flies a number of saproxylic beetles may emerge.

I briefly visited Pitsford Water, Holcot Bay yesterday to look for suitable sites for a fly identification workshop tomorrow. The workshop is one of a series that the Northants Biodivesity Records Centre is running under its WILDside Project. The project is aimed at encouraging more people to submit records of wildlife to the centre and to develop skills for the next generation of recorders.

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:

Monday, 21 August 2017

Water Quality Surveys for Citizen Scientists

I received the following email today. I know some dipterists have taken part and it is really easy. If you are interested in finding out more or taking part just follow the links. Many diptera species are aquatic in their larval stages. Some are very tolerant of high levels of pollution, for example Eristalis hoverfly larvae feed on bacteria in polluted water and have the 'rat-tail' breathing syphon that allows them to breathe fresh air whilst remaining in oxygen depleted water. On the other hand some soldierfly larvae are very sensitive to water quality and can be eliminated from a site by even minor pollution.

 Good Morning,


I’m writing to you from the Freshwater Habitats Trust to request your help to find clean unpolluted ponds, streams and ditches where wildlife can thrive.


Through our citizen science survey, Clean Water for Wildlife, we are supplying volunteers with simple kits that rapidly measure the water quality of local ponds, streams and ditches. Through the survey we hope to build a map of water quality across the country, find amazing clean (unpolluted) freshwater habitats where wildlife can thrive and to raise awareness of the true extent of nutrient pollution. Would you be able to help promote the survey to your group members? I hope this is something that is of interest.  


Why is the survey important?

Clean unpolluted water supports rich and diverse communities of freshwater plants and animals, including many of our now rarest species. It is often the best indicator of a thriving waterbody. Despite its importance very little is known about the water quality in most freshwater habitats, particularly in our smaller waters. Until recently it was only possible to measure water quality through expensive laboratory tests, now with simple kits it takes just a few minutes. With new technology it is now possible to fill in the gaps in our knowledge and it presents an opportunity to find many more really special clean waters where wildlife can flourish.


The kits

The kits rapidly measure the levels of two widespread nutrients pollutants, nitrate and phosphate, and can be used in all type of freshwater habitats (garden ponds, ditches, streams, fens, rivers and more). With these quick kits people can now actively participant in current scientific research into water quality and help to discover clean water habitats where wildlife can thrive. You can see the kits in action in our short ‘How to Video’ (


For more information please visit


Please don’t hesitate to get in touch if you have any questions.


Kind regards,



Hannah Worker
Freshwater Habitats Trust Project Assistant

(Please note I work on several projects and may be away from my desk for periods of time. This may mean there is a delay in my response)



Freshwater Habitats Trust, 1st Floor, Bury Knowle House, North Place, Headington, Oxford, OX3 9HY


You can also follow us on facebook and twitter or sign up for our newsletter Ripples or Research & Policy News


Freshwater wildlife needs you. Support us today.

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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 -
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
This was found at Abington Meadows, Northampton in September. Its distribution is mapped here

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