Suffolk Robber Flies (Asilidae)

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SUFFOLK ROBBER FLIES (ASILIDAE) A. C. HUBBARD Asilids are a group of predatory flies with mouth parts adapted for piercing other insects and sucking up their body contents. Prey includes moths, ichneumons and other species of Diptera. Morley's collection, kept at Ipswich Museum, contains a specimen of the asilid Neoitamus cyanurus with a damselfly - Coenagrion puella - as prey.

Some species capture their prey in flight whilst others sit in wait on bare ground, tree trunks, fence posts, etc., waiting for unsuspecting insects to come within ränge before moving rapidly to capture them.

Habitats include sand dunes, heathland, woodland and grassland. Morley's collection accounts for all the pre-1950 records whilst the more recent sightings are all post 1980. Grid references are only given for the latter category.

No literature search has been made so it is likely that other records do exist.

Asilus crabroniformis (Linnaeus) This is the largest species in the family and one of the most easily recognised.

It appears to be extinct in the County with no records since at least 1970.

Morley has specimens in his collection dating to the turn of the Century from an area to the south of Belstead plus a 1945 record from Badley.

Dioctria atricapilla (Meigen) There are several specimens in Morley's collection dating from the 1940s, all from East Suffolk.

Dioctria baumhaueri (Meigen) Recent records are from Coddenham Wood, Reydon Wood, Bradfield Woods, Rendlesham Forest and Sudbourne Marsh. Specimens in Morley's collection suggest it has always had a widespread distribution in the county TM 1254, 3250, 3446, 4454, 4678 TL 9256 Dioctria linearis (Fabricius) This is considered a scarce species in Suffolk and early records would seem to substantiate this with only one specimen in the Morley Collection, from Assington Thicks in July 1902. Recent records are from Rede Wood, Barham and Fen Wood, Hinton.

TM 1450, 4468, 4472 Dioctria oelandica (Linnaeus) Morley found this species in woods to the south of Belstead, his latest record being in June 1945. More recently one was found at RAF Bamham in Mav J 1995.

TL 8480 Dioctria rufipes (Degeer) There are several specimens in Ipswich Museum indicating it to be a widespread species. Recent observations would tend to confirm this with records from seven 10 km Square across the County TM 0054, 0854, 0856, 1240, 1246, 1250, 3852, 4662, 4678 4876 TL 8286

Trans. Suffolk Nat. Soc. 32 (1996)

SUFFOLK ROBBER FLIES

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Dysmachus trigonus (Meigen) A species of heaths and sand dunes. On the coast it has been recorded in this habitat from Thorpeness to Benacre with inland records from Rendlesham Forest and Icklingham. Old records of Morley's cover similar areas.

TM 3446, 3646, 4268 (AW), 4660, 4664, 4672, 5074, 5282, 5284 TL 7282 (AW), 7672 Epitriptus cingulatus (Fabricius) Another species associated primarily with heathland; recent records are from Bromeswell, Tunstall Forest and Icklingham. Away from this habitat it has been found at Bramford, Gt. Blakenham and Baylham. Morley also took specimens from Gt. Blakenham and Bramford at the turn of the Century.

TM 0878 (AW), 1052, 1246, 1250, 2046, 2850, 3852 TL 76 72 Eutolmus rufibarbis (Meigen) This is a rare species of heathland with records confined to the Breckland and more recently Rendlesham and Tunstall Forests.

TM 3446, 4052 TL 7276, 7282, 8074, 8076, 9078, 9480, 9878 Laphria marginata (Linnaeus) An uncommon species associated with ancient woodland. Morley recorded it from the woods to the south of Belstead, Letheringham Park and Brandeston.

The only recent record is from Rede Wood, Barham.

TM 1450 Lasiopogon cinctus (Fabricius) Another uncommon species found on heaths; recent records are from RAF Bamham in the Breckland. Morley also found it at Brandon and Barton Mills with East Suffolk records from Bromeswell and the Blythburgh area.

TL 8478, 8480 Leptogaster cylindrica (Degeer) Recent records include a roadside verge at Badley and riverbanks at Sudbourne and Mildenhall, all in grassland. Morley found it to be frequent in the Framlingham area with several specimens being taken in 1922 and 1941.

TM 0656, 0856, 4450, 4452, 4454 TL 6280 Leptogaster guttiventris (Zetterstedt) Morley has a specimen in his collection taken in 1928 at Tuddenham Fen. I know of no recent records of this species.

Machimus atricapillus (Fallen) A common species associated with a ränge of habitats. Recorded recently from 12 10 km. squares with several noted in the more open areas of Rendlesham and Tunstall Forests.

TM 1248, 1250, 3046 (AW), 3250, 3446, 3448, 3450, 3652, 3654, 3852, 3854, 4052, 4672, 4874 TL 6280, 7276, 7880, 8080, 9078, 9480, 9878

Trans. Suffolk Nat. Soc. 32 (1996)

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Suffolk Natural History, Vol. 32

Neoitamus cyanurus (Loew) A frequent species in Morley's day, especially in the woods to the south of Belstead. Recent records include Elvedon and Pashford Poors Fen in the west of the county and Dunwich Forest, Rendlesham Forest and Walberswick in the east.

TM 2850, 3446, 3448, 4470 (AW), 4472 TL 7282, 8080, 9234 Philonicus albiceps (Meigen) A species of coastal sand dunes it has been found recently at Minsmere. It was a frequent species on dunes to the north of Lowestoft in Morley's day.

TM 4666 (AW) Acknowledgements I would like to thank Howard Mendel for allowing me access to Morley's collection at Ipswich Museum, and Arthur Watchman (AW) for his records for this group of flies.

References & Nomenclature Drake, C. M., (1991), Provisional atlas of larger Brachycera (Diptera) of Britain and Ireland. Institute of Terrestrial Ecology, Monks Wood.

A. C. Hubbard, Treetops, Common Lane, Bromeswell, Woodbridge IP12 2PQ

Trans. Suffolk Nat. Soc. 32 (1996)