May 2015

A very belated summary for May. The weather was often cool or breezy and numbers seemed to be well down on previous years. However a few interesting flies were noted. 

We held two Hoverwatch sessions at Old Sulehay. The early May one did not turn up anything out of the ordinary but the late May session recorded Pipizella viduata and P. virens and, for the first time, Criorhina floccosa. After completing the formal counts we also recorded Criorhina berberina, Brachyopa insensilis and Brachypalpoides lentus. These last four species are all associated with dead wood or sap runs. The early May Hoverwatch did turn up the Conopid fly Myopa testacea. All Conopid records are much aprreciated as we only get a few each year. They are easy to recognise as a family but not quite so simple to identify to species as several look very similar.  

The moth traps at Pitsford turned up a few flies. The hoverfly Parasyrphus punctulatus, an early season species, was taken. This occurs in the moth traps most years but I get very few records of it from general fieldwork. Craneflies caught in the traps were Nephrotoma appendiculata and Tipula submarmorata.  

I have not received many records yet for May from other dipterists but amongst Kev Rowley's records was the hoverfly Paragus haemorrhous at Storton's Reserve. This is a new site for this species, which prefers short grasslands with bare patches that can heat up quickly in sunny conditions.

Northants and Peterborough Diptera Group April Meeting

The first field meeting of the year is always the last Sunday in April. Following the pattern of the past few years, a warm and very promising spell of weather had broken into decidedly cold and breezy conditions with the vegetation left wet after overnight rain. Not the most auspicious start to the season. We met at the roadside next to Mantle's Heath and walked over to High Wood and Meadow, Wildlife Trust reserve. The flush at the entrance to the reserve has recently had some maintenance work done on it and it looked very promising for later in the year. With the cold conditions, nothing was flying so it was a matter of sweeping the vegetation to see what turned up. The most productive area was the lower damp meadow where a mixture of rushes and grass tussocks provided some shelter for insects. The first craneflies of the season were just emerging and I found one male Tipula vittata close to the small stream at the bottom of the meadow. Several very small blackish craneflies turned out to be Ormosia lineata. These were identified from the male genitalia after dissection. Although the species is fairly widespread, it is not often recorded as it has an early flight season of April and May.

One member of the St Mark's fly family Bibionidae was caught - Bibio johannis.

Four species of hoverfly were found by me in the meadow: Melanostoma mellinum, Platycheirus clypeatus, Eupeodes latifasciatus and Eristalis pertinax. Hopefully other members of the group may have found some more. 

Damp meadows can be very good for dung flies, Scathophagidae, but I only found one species, a male Scathophaga inquinata.

With the meadow being rather unproductive I tried the wood as I thought the shelter might provide better conditions. The wood looks splendid at this time of the year with its carpets of bluebells and canopy of cherry blossom. However it did not yield much in the way of diptera. In fact I only took a single fly. This was the common Spring hairy-eyed cranefly, family Pediciidae, Tricyphona immaculata.

So, it was not a very productive start to the season but it was a very pleasant walk in a superb location.

April 2015

Since my last post I have received an earlier record of a hoverfly in Northants. On 2nd January 2015, Tim Newton found a hoverfly on his window which he correctly identified as Scaeva silenitica. We do not get many records of this species so it was a realyy remarkable find.

The warm weather in April has been bringing out the hoverflies, although I have not seen many species yet. There are loads of Eristalis pertinax about and there have been some Epistrophe eligans. The first record of this latter species came from Stuart Baker on 16th April at Southfield Farm Marsh. Graham Warnes found Melangyna quadrimaculata, another species with few records. Yesterday at Pitsford Reserve I found Helophilus hybridus and Melangyna cincta as well as a few very common species.

Earlier this week Bob Bullock sent me a photo of a blowfly he had seen at Pitsford in the Walgrave arm.  This is Cynomya mortuorum, a spectacular species with its metallic blue body and bright yellow face and jowls. We get few records of it although it is very distinctive. If you come across any recently dead animals it is worth looking round for this species. Bob said that there was a dead shrew nearby. Here is Bob's photo.

(C) Bob Bullock 2015

First Hoverfly?

I received the attached photo from Stuart Baker of the Wildlife Trust. He was working at the Southfield Farm Marsh reserve on 9th February and found this Marmalade Hoverfly Episyrphus balteatus sitting on his vehicle.

Episyrphus balteatus  by Stuart Baker

Now is the time of year in Northants when some hoverflies start to become active. Look in sheltered sunny places where the temperature will be a few degrees higher than the surrounding area. The usual first emergers are this species and the drone fly Eristalis tenax.

I attended the Dipterists Forum weekend wokshop at Preston Montford Field Centre over the weekend. This covered a general guide to identifying acalyptrate families and species identification to a group of these families where keys are not readily available. An update of Stuart Ball's key to Diptera families was provided. This included recent taxonomic changes and the workshop provided useful feedback to further improve the keys. The updated keys will be placed on the Dipterists Forum website in the members area.

Dipterists Forum workshop at Preston Montford - John Showers

Fruit fly pest found in Northants

When the moth traps at Pitsford Water Reserve are checked, the non-moth by-catch is collected and distributed to various people to record what other species have occurred. This is quite valuable as a number of species turn up in the traps that are not, or not often, found by sampling in other ways. On 13th October a small yellowish fly with red eyes and a distinctive spot on the wing was taken in the woodland moth trap. I fairly quickly determined it as a fruit fly, Drosophilidae, but as I do not have a key to this family I nearly disposed of it. However I decided to try to find a match on the internet as the wing spot was so distinctive and I knew most fruit flies do not have marked wings. A quick search revealed the likely candidate was the spot-winged fruit fly Drosophila suzukii. This species comes from Japan and is widespread in South-east Asia. It has also spread widely in Europe and the USA, where it is a serious pest of soft fruit. Unlike other fruit flies, which lay their eggs in damaged fruit, the female of this species has a serrated ovipositor which she uses to cut a hole in the skin of soft fruit and then lay her eggs for the maggots to feed on the fruit flesh. It had been forcast that this fly was likely to turn up in the UK sooner or later and sure enough it did. The first record was in August 2012 at the East Malling horticultural research station in Kent, when it was caught in a trap in the soft fruit fields. A number of other records occurred in Southern England after that. It was found this year at Winterton in Norfolk, the furthest North record so far and the Pitsford record is the first for the Midlands as far as it is known. Apart from its penchant for soft fruit crops, it will also use wild soft fruit such as blackberries, so horticultural spraying will not eliminate this species from Britain. Once more global trade  has spread an alien species into our environment with unknown economic consequences.

I have attached a fairly poor picture of the fly but it shows the wing spot (only on the male). The other diagnostic  features are the male's small black combs of bristles on the first two segments of the fore tarsi. You can just see these as small black dots on the front legs in the photo. The female is identified by the serrations on the outside edge of the ovipositor. Full descriptions, good photos and details of UK records will appear in the next ecition of Dipterists Digest, due out at the beginning of December. To confirm my identification, I sent the photo and description to Peter Chandler, who did confirm it. Two more photos added showing a bit more detail.

Hornet Hoverfly

This year seems to be the best yet for Hornet Hoverflies, Volucella zonaria, in Northants. This is the UK's largest hoverfly. The first record I received was of one at Pitsford Reservoir's Holcot Lodge on 16th July. I have also had records from Barnes Meadow, Lings Wood and Kingsthorpe in Northampton, Finedon Callybanks and Sulby. Pete Sharpe took one in his Kingsthorpe garden and brought it along for me to photograph before it flew off.

Volucella zonaria (c) John Showers

Conference on Neglected Insects in Bedfordshire