Early December

Last weekend I attended a Wildlife Trust workshop at Ring Haw where we had some interesting presentations by Roger Morris and Stuart Ball on the more challenging hoverfly genera Cheilosia and Platycheirus. They had also brought specimens to practice on. It was a really useful day and I hope it will mean that we get more records of these genera. Getting the chance to see several closely related species together is a great way to understand their differences. It is worth remembering this when starting on any new group of tricky organisms. I have been collecting some fungus gnats over the past few days and am finding that individual specimens are hard to identify to species level without some comparative material. I am trying to identify them as far as I can go but then putting them to one side until I have more material to work with. At some point I think I shall need to visit a museum to check them out. In the meantime, this is what I think I have found in December, although I still have a lot of specimens to work through.

Mycetophilidae:
  Mycetophila britannica
  Mycetophila curviseta
  Mycetophila dziedzickii
  Stigmatomeria crassicornis.

These were taken in Denton Wood by shaking withered oak leaves  that were still on the tree over an upturned white umbrella (courtesy of Mike Killerby). Also taken was a wood gnat, Sylvicola cinctus. I still have more specimens to identify.

In the garden today, several swarms of winter gnats were displaying in dancing columns in sunny spots over the lawn and borders. So far they have all turned out to be Trichocera saltator.

November 29th

A bright, frosty morning promised a few flies if I could find a sheltered sunny spot. I walked round Cold Oak Copse on the Compton Estate with other members of the "Wild Bunch".  A few small flies were darting about in the sun but I had only taken my small folding net and failed to catch any. I did manage to poot a couple of flies from tree trunks. Mike Killerby was more successful. He was beating shrubs to dislodge harvestmen and several flies dropped out, which he passed on to me. I have pinned them but only just started identifying them. Three picture-winged flies turned out to be one female Tephritis leontodontis and two male Tephritis formosa. A small cranefly with spotted wings and yellowish femora, each bearing three dark rings, was the very common Limonia nubeculosa. A pointed-wing fly was the usual Lonchoptera lutea. I still have some fungus gnats, a stilt fly and some calypterates to sort out. That was a reasonably productive morning.

When I arrived home I noticed some winter gnats dancing in the air over my garden. I managed to net three and will tackle them later. (30/11/2012 - they are male Trichocera saltator).

Now that I know beating over a white tray is effective for winter flies, I hope to get a decent list for December, weather permitting.

30/11/2012 update on unidentified flies mentioned above. The "stilt fly" was not a stilt fly but a small long-legged Empid - Tachypeza nubila. The fungus gnats were Mycetophila britannica and Bolitophila pseudohybrida. Two of the calypterates were Anthomyids and I have not retained them!

December Flies

I have just been browsing the latest issue of Dipterists Digest, number 19/2. In it Pete Boardman, from the Field Studies Council Preston Montford Centre has written an article on records of flies in December in Shropshire. He had examined the Shropshire records and found that there were none since 1945. In December 2011 he set out to record flies to see how many species were about and counted 31 species and one that is causing some identification problems. I won't go into details but I was impressed by the number.

This made me wonder what the Northants position is. I have checked the records held by me and the Northants Biodiversity Records Centre and we start in a better position than Shropshire did, although we have a way to go to reach 31 species. Here is a brief summary. Only four record sets have been made in December since 1990. The most impressive list was of 9 species at Collyweston Quarry made by Pete Kirby. The other three species were single records made by me (2) in 2011 and an anonymous record of 1 species in 2001. This gives a grand total of 12 species recorded in December since 1990!

The species are:
Stratiomyidae:
     Pachygaster atra
Phoridae:
     Megaselia serrata
Syrphidae:
     Pipizella viduata
Tephtritidae:
     Chaetostomella cylindrica
     Rhagoletis alternata
     Terellia colon
     Urophora cardui
     Urophora jaceana 
Sciomyzidae:
     Pherbellia dubia
     Coremacera marginata
Muscidae:
     Eudasyphora cyanicolor
     Polietes lardarius (the only species we have in common with the Shropshire list!) 
 
It is not surprising that there are several Tephritid flies on the list as many of these overwinter as adults. They tend to stay hidden in dense foliage unless there is a particularly warm spell. Sweeping coarse herbs, especially the plants that they breed in, may turn up some more. I was surprised that so few Muscids were recorded, but I suppose this is down to there not being many people who want to, or can, identify these bristly beasties. Looking under loose bark or in dark corners indoors may reveal a few.

So if you are fed up with pre-Christmas shopping or need to have some post-Christmas exercise, how about trying to improve the list?

Mid November 2012

A walk around Castle Ashby on Thursday produced plenty of Autumn colour and some spectacular fungi. Beech trees were particularly notable for both. However I did not find many flies. Whilst trying to photograph some fungi in the roots of a beech, I noticed a couple of very small flies running over the bark. I managed to collect one in a pooter but the other disappeared into a crack in the bark. With a bit of twig I managed to coax it out and pooted it up. One was fairly dark and the other yellowish. Under the microscope, the yellow one was easily keyed out to Lonchoptera lutea, a pointed-wing fly. The darker species was also a Lonchoptera but proved tricky. Eventually I concluded it too was L. lutea, largely by eliminating the other six British species.

On a walk near Maidwell on Saturday several hogweed plants were in flower in the road verge. They all had several common yellow dungflies, Scathophaga stercoraria, on them. These flies can be found all over Britain and in every month of the year, making them one of our most commonest flies.

Pete Sharp collected some hoof fungi, Fomes fomentarius, last week in Overstone Wood.  They showed some frass underneath, suggesting that larvae were living in them. He gave me three specimens to see if I could rear anything from them. Two are in my cold greenhouse and one in my study. I am checking them daily to see what emerges. Watch this space......

Invasive Fruit Fly

Hot on the heels of the Ash Dieback disease comes another threat to UK plants in the form of a small Asian fruit fly. Drosophila suzukii  oviposits into ripening fruit, including commercially important soft fruits and apples, pears and tomatoes.  The larvae then eat the developing fruit, which rot and drop. This obviously has potentially huge economic implications. The fly has already affected other countries such as the USA,  Canada and Italy. In its first year of detection in California it caused £300 million of damage to the fruit industry. It is not only a threat to commercial crops but also breeds readily in wild blackberries, making it virtually impossible to eradicate. This means that the only protection currently available is regular pesticide spraying.

It is easy to identify the adult fly as it is a typical Drosophila shape, about 2-3 mm long, yellowish brown in colour with darker bands at the hind edge of the tergites. The eyes are a bright ruby red and the wings have a subapical black spot. The Dipterists Forum will be publishing more information and encouraging members to look out for it and report it. In the meantime if you want to see what it looks like, here is a link

http://www.agf.gov.bc.ca/cropprot/swd_identification.pdf

VC32 Diptera Group Newsletter

As the field season is pretty well over, I am trying to catch up with identification of flies that I put aside earlier in the year when the lure of fieldwork was greater than my capacity to process the catch. I am also starting to receive records from other group members and would like to get them all processed early in the new year. I then hope to produce the next newsletter in January. Any articles or photos for the newsletter or indeed this blog are most welcome.

I have added a tab to the blog that will take you to the group's newsletters. I have only added the latest, number 12, as there is not an easy process to move the newsletter onto the blog - you have to cut and paste the text, then insert the photos and then edit the text for headers, spacing etc.. I shall, however, add future newsletters.

I am looking forward to the Dipterists Forum Members Day and AGM at Bristol Museum on 24th November, not least because our own Jolyon Alderman will be giving a talk, entitled "Off the beaten track: a season of swarm chasing".  The Dipterists Forum website has more details.
www.dipteristsforum.org.uk

Late October 2012

Things are now fairly quiet on the fly front and I expect the forecast cold snap will finish off a few of the flies that are still about. A walk in Sane Copse, Yardley Chase, this morning produced one hoverfly Melanostoma scalare (Fabricius). It had been visiting a flower of Ragwort when I saw it.

Apart from that, I noted the Dryomyzid Neuroctena anilis (Fallen). This is a common woodland species in the Autumn. The mines of Agromyza alnivora Spencer were plentiful on the alder leaves. Whilst examining leaves of beech for mines, I found a very distinctive gall. It consisted of a pustule on both sides of the leaf but on the upper surface a cylindrical growth rose about 4mm from the pustule's centre. Using the excellent "British Plant Galls" by Margaret Redfern and Peter Shirley, I discovered that it was caused by the Cecidomyid fly Hartigiola annulipes (Hartig). So not a bad morning despite the weather.

On 18th October, also in Sane Copse I took three flies. One was the hairy-eyed cranefly Tricyphona immaculata (Meigen). This is a smart, black species, a colour that is not very frequent in craneflies. A small lance-winged fly was Lonchoptera bifurcata (Fallen) and a dung fly was not the usual common yellow dung fly Scathophaga stercoraria (Linnaeus) but another common species S. furcata (Say).

Whilst tidying up the garden earlier in the week I noticed a gallery leaf mine on columbine Aquilegia. It is caused by the Agromyzid fly Phytomyza minuscula Goureau, a new species for my garden.

More about Calliphoridae (blowflies)

Following on from Tony White's piece on Pollenia species on ivy, he sent me another record. This time of the very colourful Calliphorid Cynomyia mortuorum (Linnaeus). This too was feeding on ivy flowers in Byfield. I have not seen this species in Northants and nor have I received any previous records. However, it is a widespread species so should be recorded more frequently. I did see one whilst on the Dipterists Forum field trip to Speyside and the Cairngorms in July. We were investigating a promising looking area of bog and old pines close to the Cairngorm Lodge Mountain Centre near Aviemore. A dead shrew was lying on a stump and several calliphorids were visiting it. These included the C. mortuorum. I took the photos below.

Cynomyia mortuorum (bottom right) and other calliphorid flies on a dead shrew, near Aviemore.

Closer view of Cynomyia mortuorum.
All photos on this blog are copyright John Showers 2012.

Late Season Flies

Tony White has sent me the following article on cluster flies and ivy. I remember when I worked for what is now Tata Steel Europe in Corby that at this time of the year my office and other offices at the corners of the building were plagued by hundreds of cluster flies Pollenia rudis as these flies emerged from the surrounding grassland and sought overwintering quarters in the spaces above the false ceilings.

 Ivy flowers and Pollenia species

Shelley reminds us that “The yellow bees in the ivy bloom” (Prometheus Unbound), but there are lots of diptera to interest us too, with ivy's nectar providing the last great feast of the year for many species.

Prominent among these are species of Pollenia and an excellent online key is to be found by looking for “Cluster Flies of North America”. Although it is a key to Canadian species it covers all British species with the exception of Pollenia amentaria and P. viatica (the latter species being easily recognised by its almost-black abdomen). Using this key I have been able to record Pollenia angustigena

and P. pediculata from ivy in the Byfield area (as well as the ubiquitous P. rudis) and it seems likely that these species are quite widespread and much under-recorded.

Now where can I find a reliable key to Calliphora species!

Tony White

Some of last week's flies.
 

On Thursday morning I was at Grendon Lakes and noted large numbers of muscid flies sitting on tree trunks and foliage in full sunshine. They were very wary but I obtained three as a sample. They keyed out to be the common muscid Muscina levida, all males. I am not sure whether these were mating swarms or just a plentiful fly finding opportunities to warm up. Several Eristalis hoverflies were visiting ivy and on the few hogweed plants that were still in flower some other species were present. The most notable of these were Cheilosia soror but I also found a solitary Platycheirus that keyed out to P. splendidus. This species is primarily a Spring species and the specimen I took was a female, so it might be P. scutatus. This latter species is much more frequent in the Autumn and females of this group are only dubiously separable, so maybe it is better recorded under the aggregate name. At the same site, Jeff Blincow showed me an elongate bright metallic green soldierfly, which was the Autumn-flying Sargus bipunctatus.

Leaf Mines

Autumn is a good time to look for leaf mines. A number of groups of insect have larval stages that feed in leaves, leaving a characteristic trail. As many leaf miners are specific to one or few species of plant, it is often possible to identify the insect from the pattern of the mine and the species of plant. These websites are useful guides to identifying leaf mines.

http://www.leafmines.co.uk/index.htm

http://www.ukflymines.co.uk/index.php

Amongst the flies, the family Agromyzidae is the main group that make leaf  mines. Some hoverflies 
also have leaf mining larvae. Notably Cheilosia caerulescens is a miner of house leeks Sempervivum. 
It has not yet been recorded in Northants but has been found in Bedfordshire. Look out for mined 
leaves of house leeks. Visits to garden centres may be productive as it is thought that the fly entered
Britain in imported plants.

When the weather is not suitable for finding adult flies, looking at leaf mines is a good way of 
recording species. Last week I found Agromyza filipenduli on meadowsweet, Liriomyza eupatorii
and Phytomyza eupatorii on hemp agrimony and Agromyza alnivora on alder leaves at Yardley
Chase.

Phytomyza eupatorii leaf mine on Hemp Agrimony

 Agromyza alnivora leaf mine on Alder

Agromyza alnivora leaf mine on Alder. The larva is visible as a small dark object at the top of the mine (not
the larger brown blotch)

Late Summer Diptera

Towards the end of the Summer, the weather has been more conducive to hoverflies. In particular there have been very good numbers of Eristalis species visiting plants such as Wild Angelica, Wild Carrot and Hemp Agrimony. As the Ivy comes into flower this too attracts a lot of species.

Eristalis species visiting Wild Angelica near Yardley Hastings.


I have had several reports of Volucella inanis and a couple of reports of the even larger hornet mimic Volucella zonaria in Northampton.

Volucella inanis at Boddington Meadow Nature Reserve.

The hoverfly Rhingia rostrata has recently colonised many parts of Northants. It tends to be more frequent in Autumn, although I did note it a couple of times in the Spring. It can be separated from the more common Rhingia campestris by having all-yellow legs and no black edges to the abdominal segments.

Rhingia rostrata at Rothwell Gullet Nature Reserve.

Autumn also brings out a number of cranefly species. The most prominent is the long-palped cranefly Tipula paludosa. This can emerge in large numbers from damp grasslands and frequently enters houses.

Tipula paludosa at Rothwell Gullet Nature Reserve.

Restarting the blog

I am afraid I forgot all about the blog and it was only seeing the excellent Northamptonshire Birds blog run by Neil and Eleanor McMahon that reminded me. Anyway I intend to get it going again so if you have any Diptera news or photos do let me know.

This year has been very poor for Diptera but the past couple of weeks or so have seen something of an improvement and maybe the season will turn out to be interesting. Particularly notable are the large numbers of hoverflies visiting umbellifers, especially wild angelica and wild carrot. Many of these are Eristalis species, mainly E. pertinax and E. arbustorum but the other common species are present if you look carefully. In my garden, marjoram is also attracting a lot of hoverflies at present. At least 10 species of Hoverfly have been around over the weekend. Also in my garden I have been invaded by the weed Soapwort Saponaria officianalis. It is a nightmare to control. However it has added a new fly record to my garden list as its leaves are mined by the Agromyzid fly Amauromyza flavifrons.