Creating Dead Wood Habitat

Many species of fly, as well as beetle, wasp, bee and moth breed in dead or rotting wood. Many of these saproxylic insects are declining. Continuous availability of suitable habitat is required for many of these insects. Clear felling of woodlands often leads to a break in availability of wood of suitable size, age and degree of decay. Added to this, tidying woods to remove dead branches and trunks to reduce risk of fire or of injury further reduces suitable habitat. Many woodland managers are recognising this and are starting to be more sensitive to saproxylic insect needs. In many cases dead wood piles and branches are left on the ground as habitats. However, many species require standing dead wood or living wood with rot holes. Last week, with help from the wardens at Pitsford, I had a go at trying to create some habitat in stumps of felled trees. This was done by chiselling out a depression in the cut stump and filling the depression with the wood chips. Eventually these will fill with water and start to rot. Here are a couple of photos of the stumps:

It will take some time before anything happens but I shall keep an eye on them and see what develops. I may also try to make some more in taller stumps as these will eventually simulate standing dead wood.

I have previously had some success with artifical rot holes made from empty plastic drinks bottles, with a hole cut in the side and filled with rotting vegetation and water. The woodland hoverfly, Myathropa florea, has successfully bred in these. It is important that the filling does not dry out.

                                           Myathropa florea

Late February

Last weekend I attended the Dipterists Forum identification workshop covering the Heleomyzid and Lauxanid flies. It also covered one or two other families of acalypterate flies with spines on the costal vein of the wing. It was a very useful session and good to catch up with friends I have made at previous workshops and field meetings.

I was able to identify a few specimens that I had taken locally, including the Heleomyzid that I found at Yardley Chase a couple of weeks ago. This was Tephrochlamys tarsalis, a female. A number of Heleomyzids are active in winter, which probably means they are under-recorded as not many dipterists are!

I was also able to look at the new hoverfly book by Roger Morris and Stuart Ball. They had been given a pre-publication copy. It looks very good, with excellent photos and should help with field identification. It is due to arrive in the UK on 5th March and should be available shortly after that. Dipterists Forum members should be able to get it at a discount.

Heleomyzid fly photo taken with an iPad through the eyepiece of a microscope.

My first hoverfly of the season

I have been spending the day in the garden, trying to prune some shrubs and clear back some ivy that is threatening to engulf the borders. I don't want to get rid of the ivy as it is such a good plant for wildlife but it does need to be kept on a tight leash.

Anyway, the sun was bright and the more sheltered parts of the garden felt quite warm. I saw a peacock butterfly fluttering in the sun so had high hopes of a hoverfly. Examination of the leaves of Bergenia revealed a single drone fly Eristalis tenax. This is usually the first hoverfly I see in the garden each year and is usually on the Bergenia. I think the combination of early flowers and a sheltered sunny position make it a very attractive spot.  I expect the marmalade hoverfly, Episyrphus balteatus will be the next hoverfly species to occur, as it too overwinters as an adult.

On Thursday morning I joined the Wild Bunch for our usual foray into Yardley Chase. The highlights were woodcock and a lesser spotted woodpecker. This is the first I have seen for over 10 years in the county. I had high hopes of finding a hoverfly as there were some good sunny intervals. One promising area was a large manure heap, which should have provided a warm microclimate for flies. Sure enough there were several midges and, on close examination, I found some higher flies. I did not have a net and did not fancy pooting off manure so catching any was a problem. I did manage to get a tube over one fly and bring it home for identification. It is a heleomyzid fly. These characteristically have prominent spines along the wing's costal vein. At present I do not have a key to species but luckily next weekend's Dipterists Forum workshop is covering Heleomyzidae and Lauxanidae so I should be able to identify it to species. I have one or two saved heleomyzids and lauxanids to sort out so may be able to add some more records.

I see that Roger Morris in his blog (see Links) is trying to encourage keen wildlife photographers to photograph hoverflies in their gardens so that he can try to identify them to see what occurs. He notes that Jenny Owen had 90 species of hoverfly in her garden over the years she did her recording. I must see how many I have found so far.

Early February 2013

The cold weather has meant I have not made much effort to look for flies, rather I have been trying to catch up with identifying material I took at the Dipterists Forum's Summer field meeting at Speyside. I have found several species of hoverfly that I have rarely, if ever seen before. I have a lot material to work through before the season starts.

 I have only recorded two species of fly in Northants so far this year. On the last day of January, beating an evergreen bush at Castle Ashby yielded the fungus gnat Mycetophila ocellus.

Today I visited Pitsford Reservoir and spent some time looking at dead wood and searching leaf litter. The best thing I found were 3 woodcock but I did find one fly. It was in leaf litter very close to a pile of deer droppings. Appropriately enough it turned out to be a lesser dung fly, Sphaeroceridae, a female  Crumomyia fimentaria. This is a widespread species but, as few people record them, it is a new record for the reserve.

John O'Sullivan, the Bedfordshire recorder for hoverflies tells me that he has had a few records of the marmalade hoverfly Episyrphus balteatus and the drone fly Eristalis tenax. So there are hoverflies about still.