Worcestershire Record No. 5 Nov 1998 p. 15

DIPTERA - SOME SCARCE FLIES RECENTLY IN WORCESTERSHIRE

Hoverfly - Herringia (Neocnemodon) brevidens (Egger)(Syrphidae) - Bishops Wood, near Stourport-on-Severn - June 1998. Hover fly course.

Hoverflies in the woodland were identified using Alan Stubbs (1983, 1996) - all were widespread common species. At the end of the day we caught more flies to take home. Hoverflies are noted for their bright markings, but there are some genera of smallish blackish flies that for this reason are less recorded. A possible way of finding them is general sweeping with a net in rideside vegetation with flowers; - of those captured I identified a male Heringia (Neocnemodon) brevidens, the male distinguished by a small tab on the basi-tarsus of forleg see drawing from Stubbs & Falk). A key to the male genitalia (Speight & Smith 1975) helped confirm identification. A seldom recorded species, probably under-recorded, national category Notable (scarce), possibly reflecting that under-recording, rather than rarity, provides few records. The draft UK hoverfly atlas states records post-1960 in only seven 10x10km squares (Alan E. Stubbs pers comm 1998). Stubbs (1983) gives records: 1949, on flowers in SW London; a park with a pond, N London; 1983, a wood in Warwickshire (P. Withers). Nearest known site to Worcestershire is Solihull, Birmingham (draft atlas). Larvae of Heringia (that now includes Neocnemodon as a subgenus, not a genus) are predaceous on arboreal aphids on Ulmus, Populus, & Malus according to Rotheray 1993. Rearangement of genera reflects a trend for groupings of species and genera based on the immature stages of flies, as well as on the adult forms that were described relatively long ago, before the larvae were taxonomicised. Chandler 1998, Diptera check list, just published, gives name Heringia (Neocnemodon) brevidens (Egger 1865), as a species added to the British list by Stubbs 1980.

Crane fly - Limonia masoni (Edwards) Limoniidae - Tiddesley Wood, Pershore - late May 1998.

A visit to the south end of Tiddesly wood, which probably involved some general sweeping within the trees and shrubs (the wood is opening out at ground level naturally over the years) resulted in a small very shining brown and black crane fly, with wings slightly yellow at the leading edge, with also three small brown spots along this edge (more or less) and tip of the wing narrowly black. Allan Stubbs 1998 test key to Limoniinae describes it as an extra-smart species, and the key indicated Limonia masoni (Edwards), a rare, RDB3 species, that Alan Stubbs has just confirmed. A fly of alkaline soils.

Crane fly - Tipula helvola Loew (Tipulidae) - Mill Meadow, Drakes Broughton - late June 1998.

I often visit this small meadow, that is almost boggy at one end, enclosed on three sides with limited woodland, with a small pond. There are some small oaks that have been pollarded by WWT at about 1.5m (to keep the small meadow open); some have died from this treatment and the fungi is a source of beetles, while others have become micropollards. In Worcestershire, and Britain generally I would think, meadows surrounded by woodland are uncommon, and are interesting conservation features. Black Meadow in Chadesley Woods, which I saw this spring teaming with insects, would be worth surveying in detail. At Mill Meadow I probably found the female fly on tall nettles near the pond; I took it home and did not clearly identify it at the time, and largely forgot about it, which was easily done because it was nondescript, of average size, lacking in character, until I showed my collection to Alan Stubbs last week & he pointed out it was Tipula helvola, a notable species, that is mentioned next.

Crane fly - Tipula helvola Loew (Tipulidae) - at a moth trap on Craycombe Hill, near Evesham - June 1998.

A mainly mixed wooded hill with some garden ponds near Wood Norton, near Evesham. As well as moths, flies are attracted to light, but most of them, apart from a limited number of usually the larger crane flies, fail to become trapped within the trap because they fly around the light on the top or find their way out even if they do enter inside, unless the trap is fitted with a fan. However we were using ordinary moth traps, and I pooted a selection of flies from around the light and we netted a few crane flies - hence 26 species of fly of 14 families;- including a male Tipula helvola Loew (Tipulidae), a notable (JNCC 1997, Falk 1991) species of nondescript appearance, of average size, with the identifying feature of a whitish blister-like swelling of certain size on the genitalia. Alan Stubbs' test keys (Stubbs [?]) enabled accurate identification. The old RES key Coe 1950 contains some alternative description but more persistence is required to come to a less certain conclusion. Because of drab nondescript appearance this fly is possibly under-recorded. There are 17 post-1960 sites (S England, Kent & Cornwall, to as far north as Wiltshire, and sites in N Wales)(Alan Stubbs pers. com.); appears associated with gravelly soils; and the larvae are thought to be in dry soil; somewhat unusual for a crane fly (Falk 1991); but I have found this species at Mill Meadow, which is a rather damp area so perhaps the habitat of this fly is wider-ranging. Has not been recorded around this part of England before. Light trap fly surveying is a little-used technique. I have yet to compare the Malaise fly trap (a tent like structure) with the light-suction trap. Next year I am planning to suspend a light suction trap in woodland canopy. Light traps with fan-suction are also good for lightweight micromoths I have observed, because unlike typical Noctuids, micromoths do not immediately dive down the funnel without the force of air flow.

Acalypterate fly - Sapromyza bipunctata Meigan (Lauxanidae) - church-side footpath to Grafton Wood - early August

Intending to beat insects out of vegetation inside the wood. Fortunately forceful beating broke the stick down to about 30cm - suitable for beating mixed hedges around fields around the wood. Maximum yield was in south facing corners. Technique is to press the beating tray into the hedge someway down from the top, and hit the hedge above. Organic debris and invertebrates fall onto the tray; many flies fly, but one noticeable specimen fell onto the tray & sat there, as perhaps characteristic of many Lauxanidae, that seem often reluctant to fly; possibly they are more active at night. Some of them are pale and obvious and found immobile on leaves. This species was Sapromyza bipunctata Mg., according to use of Colin 1947 (key), and very local, with records Cambs, Suffolk (common at edge of Breck district), and Essex only according to this old key. Now considered Notable (JNCC 1997, Falk 1991); quite possibly under-recorded through disinterest. Larvae of some known to mine dead leaves, a special case of the primitive compost feeding larvae (Oldroyd 1964). Adults generally quiet living in shady conditions (Colyer & Hammond 1968). Of genus Sapromyza, apicalis (R-D) reared from garden earth; basalis Zet. from leaf litter; obsoleta Fall. from rotting vegetable matter; sordida Haliday from wrens' nests. Lauxanidae worldwide - 1500 species; Britain - 46 species. None appear to have any economic importance, an explanation of entomological neglect of a large family. (Smith 1989.)

Hover fly - Rhingia rostrata (L) - Tiddesley Wood, Pershore - late September 1998.

Harry Green found two hover flies with orange-brown abdomens, & projecting conical lower faces (for feeding in tubular flowers). The usual key Stubbs 1983 indicated Rhingia rostrata (L.)(notable = scarce), and Rhingia campestris (Meigan)(widespread). The separation of the species is that the very edge of the side of the abdomen of rostrata lacks any black line. R. rostrata used to be considered RDB2 and vulnerable (Shirt 1987), but is not as rare as first thought. The Wealden counties, S. Chilterns, and parts of Wales are among the areas with moderate numbers of records; usually seen September; and is double brooded (Stubbs 1996). R. campestris breeds in cow dung as described by Coe 1942 who followed the life history. The adults oviposit onto the undersurface of small plants such as clover overhanging fresh dung, the eggs hatch, and the larvae creep down onto the dung surface, or drop down if there is a gap, and search for a crevice in the crust, and live and feed within the pat, finally pupating in the tangled roots at the base of the dung remains. However R. campestris is found so far from cow dung that there seems reason to believe alternative food for the larvae is used. Collecting badger dung might reveal something and possibly even R. rostrata.

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