Early February 2014

After a couple of months of doing admin and identifications, I managed a little fieldwork today (6/2/2014). The recent gales had toppled some Scots Pine trees in Denton Wood and I took the opportunity to beat the still-green leaves to see if any insects would fall out. I struck lucky and two picture-winged flies fell into my tray. At first I thought they were the same species but examination under the microscope showed clear differences. The first was Tephritis neesii, a species I have recorded earlier this winter. The second was Tephritis vespertina, which I have never seen before. It has very distinctive wing markings, with a broad dark V mark spanning a small white apex to the wing and vague dark markings between the anal veins. Both specimens were males. 

I have also two other species of fly from a Spruce but they are both Frit Flies Chloropidae, and I do not have a key for these at present. I have retained the vouchers so if anyone does have a key and wants to identify them, they are available.

I then tried beating some standing spruces but did not find any flies. However I did find a larch ladybird,  Aphidecta obliterata.

Late November 2013

Although the weather has been getting colder there are still some flies about. In particular beating dead leaves on trees and shrubs can often dislodge overwintering Tephritid flies. These flies form galls on various plants but particularly members of the Asteraceae, daisy family. Each fly species is associated with particular plant species and the galls are firmed in particular parts of the plant. One of the commonest species is Urophora cardui, which forms a distinctive gall in the stems of creeping thistle Cirsium arvense. Several of these were present near Yardley Chase on 21st November.

Swollen stem of creeping thistle caused by the Tephritid fly Urophora cardui. The fly itself is very distinctive, having black wing markings of two inverted U shapes that are joined on the trailing edge of the wing. If the two U shapes are not joined, this is another species.

Urophora cardui

Apart from the above gall, adults of other Tephritid flies have been noted over the past couple of weeks: Tephritis formosa, T. neesii and T. hyoscami all in the Yardley Chase area. All of these flies have distinctively patterned wings and are frequently referred to as "picture wing flies". The term covers members of several families, not just the Tephritids. 

It is possible to find the galls of these flies in the heads of various thistles in winter. If you squeeze the dead flower head you can sometimes feel a hard capsule inside, which is the gall. It is possible to raise the adult fly from the gall to confirm which species has made it.

Other signs of the larvae of flies in winter can be leaf mines. Here is blotch mine in the leaf of hedge woundwort Stachys sylvatica. This is caused by the Agromyzid fly Amauromyza labiatarum. It was found at Yardley Chase.

Early November 2013

Although it is getting colder and wetter there have been some fine sunny intervals and in sheltered spots there are still plenty of diptera about. I was looking at some flowering ivy at the edge of Rothwell on Monday and it was covered in flies. These were mainly muscids and calliphorids but a few hoverflies were present: Eristalis pertinax, E. tenax and a Syrphus species. There were several Mesembrina meridiana there too. Here are some photos.

Eristalis tenax

Eristalis pertinax

Mesembrina meridiana (Muscidae)

In my own garden the ivy has not flowered but I do have a plant of the ivy x Fatsia hybrid Fatshedera. This does produce ivy-like flowers, which start to open in early November. It provides an extension to the nectar season. On Monday Episyrphus balteatus was visiting it. Today only common wasps seem to be around.

Late October 2013

A walk in Ravenstone Road Copse, part of Yardley Chase, last week produced only a few flies. Several small craneflies were disturbed from the ride edges and turned out to be Tipula pagana, one of the subgenus Savtshenkia. I then caught two more in my moth trap in the garden in Rothwell the next day. 

There were some spectacular fungi growing in the wood and several fungus gnats were seen disappearing under the caps of honey fungus Armillaria mellea. They kept flying into grass tussocks or onto a tree trunk and were hard to observe. I did manage to net some. They all turned out to be Mycetophila britannica males. There was also one lesser house fly Fannia parva in the net.

Honey Fungus Armillaria mellea

Mycetophila britannica on Honey Fungus (c) Jeff Blincow

A walk round my garden today only produced the one species of hoverfly, Helophilus pendulus. These are regularly sitting on the leaves of a variegated sedge at the side of my pond. I suspect the males are waiting for females as their larvae develop as rat-tailed maggots in the pond.

Helophilus pendulus taken at Boddington Meadow last year

Early October

Most of September I was either in France & Germany or down with a heavy cold so I have not much to report.  I have done no field work on flies but have been helping with the Nene Valley Ecology Group's water invertebrate surveys and found several new beetles for me.

Anyway, back to flies. At the beginning of September my garden in Rothwell still held several Tachina fera, visiting marjoram flowers. Marjoram is a must have if you want to attract insects to your garden. I also noted Eristalis tenax, E. Pertinax, E. Arbustorum, Myathropa florea, Syritta pipiens, Eupeodes luniger and Helophilus pendulus hoverflies. Helophilus pendulus is still around the pond in early October.

On warm Autumn days like today one of the best ways to find nectaring insects is to look for some flowering ivy. I shall be searching the hedgerows and wood edges for suitable ivy patches over the next few days. There has been a large emergence of the long-palped cranefly Tipula paludosa and many are coming into the house. Later this month, its close relative Tipula subcunctans should be about.

Whilst trying to shake off my cold, I was able to catch up with identification of some flies that I took earlier this year. The Dipterists Forum held its Spring weekend field meeting in the Rockingham Forest area and I collected quite a few flies that I am still working through. The weather was poor for two of the three days so finding flies was hard work but I did add some new species for me. Titchmarsh Wood, part of the Souther Wood complex turned up Empis nigritarsis and the parasitic fly Lypha dubia.  I still have more to do so am hoping for other new finds.

Late August 2013

Since my last blog about mimicry in hoverflies an example of its ability to confuse cropped up on BBC 2's recent Horizon science programme on what's happening to our bees. At one point it showed a "honey bee" which was, in fact, the hoverfly Eristalis tenax.  Oh dear! This is not the only example of hoverfly photos being used to represent bees. I remember browsing in a bookshop a few years ago and picked up a book entitled something like "Bees of the World" and the dust jacket photo was of an Eristalis hoverfly. It did not encourage me to regard the book as an authorative reference work.

Usually in late July and August Britain receives a large number of migratory hoverflies along with butterflies, moths and dragonflies. It is usually signalled by a sudden increase in the marmalade hoverfly Episyrphus balteatus and a few Scaeva pyrastri accompanying them. Although there have been plenty of Silver Y moths and Clouded Yellow butterflies about, I have not seen a great deal of evidence of a major hoverfly influx. There were plenty of E. balteatus about but I was seeing them in tens on most sites, not hundreds, and I have seen only one Scaeva pyrastri. There have been one or two sightings of Eupeodes latifasciatus, which may be a partial migrant, but overall I do not get the impression of a significant hoverfly migration in this area. I do not know if this is a general view across the country. I might raise the question on the Hoverfly Recording Scheme website.

One hoverfly that did catch my attention this week was of a Syrphus type with more black on the legs, particularly the hind femora, than with the usual species. Also the yellow bands on the tergites seemed to dip down towards the outer edges.  I managed to poot it off a bramble and took it home to identify. It turned out to be Didea intermedia, possibly a first for Northants. I took it in a wood with several blocks of conifer plantation. It was easy to key out and I was able to confirm it by comparing it with a couple of specimens I had from Speyside, its main stronghold in Britain. Interestingly, the following day someone reported one from Gloucestershire, a first for that county too. Also in the wood was Sphegina clunipes, a species for which we receive few records, although it is widespread in Britain. I rarely bother with conifer plantations but sometimes it is worth looking at different habitats, no matter how unpromising they may appear.

Hoverfly Mimicry

Over the past month there have been quite few hoverflies that mimic bees or wasps about. Some of the mimicry is really good and some less convincing, at least to our eyes. Harmless species that have evolved to look like potentially dangerous or distasteful species are examples of Batesian mimicry. There are many examples in the hoverfly family. Here are some photos that I have taken over the past  few weeks.

Volucella bombylans mimics several bumblebees. This photo shows the red-tailed form which mimics Bombus lapidarius or Bombus rupestris. V. Bombylans also has a white-tailed form mimicing  Bombus lucorum or Bombus hortorum.

Eristalis pertinax mimicing a honey bee.

Myathropa florea mimicing a social wasp

Xylota segnis - is this mimicing a solitary wasp?

Chrysotoxum festivum mimicing a social wasp

There are many others I could have shown. Look carefully at the "bees" and "wasps" and you might be surprised at how many turn out to be hoverflies or indeed other families of fly (Conopidae for example) or other insects such as wasp beetles.