May is my favorite time for walking in the British woodlands, with the less dense foliage of the trees, there is often an array of colourful flowers that attract insects.
Myopa testacea Linnaeus, 1767. Conopidae.
This Conops fly first appears in the spring and my find was along a path at the bottom of a small steep sided woodland on the chalk. M. testacea parasitises some of the common spring Andrena mining bees, inserting an egg into the abdomen of the chosen host, hence their often used English name of bee grabbers, the mature Conopid larva eventually pupates within the host. A fairly widespread but local species.
Myopa testacea. Chalk woodland, Wiltshire, May.
Sphegina clunipes Fallén, 1816. Syrphidae.
This very small unusual looking hoverfly was found in the small woodland mentioned in connection with the last species, the only place I have yet observed it. It has a dainty flight, but seems to hardly ever rest as it flits through the undergrowth in dappled light. This species likes damp woodland, often near a stream, the larva develop under dead bark on living trees or under the bark of fallen trees in shady conditions.
Sphegina clunipes. Chalk woodland, Wiltshire, with habitat. May.
Rhingia rostrataLinnaeus, 1758. Syrphidae.
Rhingia rostrata is the less frequent of the two snout hoverflies that occur in Britain, it was once much rarer but in recent years it has spread across Southern England, but it seems to be currently absent from my region. My first finds were in a limestone wood in Somerset where the males especially sought out the Ramson, Allium ursinum flowers but it was not especially common there, occurring with the darker and more frequent Rhingia campestris.
One remarkable day in Savernake Forest in Wiltshire, on a bright summer's morning, produced not only the other three local species of the bee mimicking Criorhina in one area but also two mating pairs, which are very rarely seen. The larvae of all three species live in rotting wood. Both forms of Criorhina berberina were encountered, the buff form oxycanthae, a mimic of Carder bumblebees and the typical form, an excellent mimic of Bombus hypnorum. Several of both forms of C. berberina were flying around the base of an old sycamore tree and slowly quartering the ground around, obviously looking for a newly emerged female, or perhaps waiting for one to emerge. On this and subsequent visits, I saw a number of Criorhina floccosa males holding territories around the base of large old beech trees within the forest, usually there was one individual but if another appeared they would engage in combat, locking together, often rolling around on the ground in the dead leaves, the victor emerging to sit on his preferred spot on the moss covered base of the tree, ready to claim any emerging or visiting females, while the vanquished retreated to try his luck elsewhere. The Criorhina asilica males were very active along a woodland ride, flying at speed, rarely resting, on their endless search for females. Occasionally I saw the males of both C. asilica and C. floccosa in this area, visiting the yellowish-green flowers of the sycamore trees.
1 & 2. Criorhina floccosa mating pair and male at the base of a beech tree
3 & 4. Criorhina asilica mating pair and a male.
4 & 5. Criorhina berberina male form oxycanthae and typical form.
Meligramma euchromum. Kowarz, 1885. Syrphidae.
One May morning in Savernake Forest, I found basking in the sunshine Meligramma euchromum, a really good find because it is a rare and elusive species that is thought to be mainly arboreal. I only managed one quick shot, before it vanished upwards.
A Dipterists year. May. Cannock Chase, Staffordshire.
Chalcosyrphus eunotus Loew, 1873. Syrphidae.
This is a rare hoverfly that occurs in a specialized habitat, the larva developing in small partly submerged fallen logs in shady woodland streams. One such stream is on Cannock Chase in the country of Staffordshire, where on a bright spring morning I put on my wellingtons and proceeded along the stream through the dappled shade of boggy Alder woodland that was here and there bright with yellow marsh marigolds. It took some time to find an individual sitting in the middle of the brook on a small log, the males hold territories and will attack any passing insect, one has to approach them very carefully, not easy to do in the swift current. One or two others males were seen and I was very fortunate to find the rarely seen female, which was running about a small decaying birch log, stopping to lay an egg here and there, in a crevice. There are two species of the genus Chalcosyrphus in Britain, the other is C. nemorum, a smaller species, which although local, is much more widespread than C. eunotus and it can be found in a wide range of wetland and woodland habitats. I also observed C. nemorum males along the Cannock Chase stream, sitting about a fallen tree lying across the stream.
Orthonevra brevicornisLoew, 1843. Syrphidae. The Cannock Chase stream, also produced another rather scarce hoverfly, Orthonevra brevicornis which is confined to streams and spring-fed marshy areas in Alder carr. This is a small species, with scattered records mainly in Wales, the West Midlands and East Anglica. The larvae are thought to develop in organically-rich mud.
Just beyond the Alder Carr on Cannock Chase, was a damp meadow, and this produced another good hoverfly in the form of the wasp mimic Chrysotoxum arcuatum, which is smaller than the very similar species in this genus. I have first encountered this hoverfly in the Alps of Switzerland but it was the first time I have seen it in Britain, where it is a northern species. The larvae are thought to feed on root aphids associated with ant colonies.