Wildlife Review 2023: True flies (Diptera)

This section covers all true flies recorded except for hoverflies, which are covered separately. A total of 139 species were identified this year including 14 new species. This compares with 126 species in 2022 and 140 in 2021.

Diptera is one of the largest and diverse of insect orders covering numerous family groups. Identification can be difficult and only possible in many cases by microscopic inspection. However, good numbers of species are readily identified by observation and closeup photographs.

Species from the Agromyzidae family were recorded from their leaf mines. These are caused by larvae feeding within the leaf. Individual species can often be identified by the pattern of the mine, frass and the host plant.

Thirty-one species of several families were identified including Agromyza filipendulae in Meadowsweet, Amauromyza verbasci in Mullein, Aulagromyza poplicola in Lombardy Poplar, Cerodentha iraeos in Yellow and C. iridis in Stinking Iris, Liriomyza eupatorii spiralling in Hemp Agrimony, Phytomyza ilicis in Holly, and a new species, Chromatomyia scolopendri in Hart's-tongue Fern on 2nd December.

Chromatomyia scolopendri tenanted leafmine - Kevin Rylands

Several distinctively marked picture or wing waving flies (Tephritoidea) from various different families can often be encountered on site. Species recorded this year including Looped Flutter-fly Palloptera muliebris on 27th July; Celery Fly Euleia heraclei from 13th May, Tephritis vespertina from 20th May and Banded Burdock Fly Terellia tussilaginis from 29th July; Bandless Spotwing Melieria omissa on 11th June and Band-winged Wingwaver Ceroxys urticae on 16th July; and new for the Warren, a Peplomyza litura on 3rd August.

Tephritis vespertina - Kevin Rylands

The closely related grass flies (Chloropidae), are a difficult group to identify but the distinctive Camarota curvipennis was discovered new to site on 26th October.

Camarota curvipennis - Alan Keatley

Marsh flies (Sciomyzidae) included Grey-backed Snailkiller Pherbellia ventralis on 24th January, Field Buff Snailkiller Tetanocera elata from 19th May, Common Buff Snailkiller T. ferruginea on 5th October, and two new species for the Recording Area, Chalk Snailkiller Dichetophora obliterata on 31st August and Knutson's Little Snailkiller Pherbellia knutsoni on 14th November. The closely related Hooded Dryomyza D. anilis discovered on 28th September was also new.

Chalk Snailkiller Dichetophora obliterata - Alan Keatley

Along the strandline varying numbers of Bristly-legged Seaweed Fly Coelopa frigida were present most of the year, surprisingly the close relative Furry-legged Seaweed Fly C. pilipes seen on 7th April was new for the Recording Area. In the same habitat the Anthomyiid fly, Fucellia tergina was recorded on 22nd April.

Furry-legged Seaweed Fly Coelopa pilipes - Alan Keatley

Heleomyzidae are small flies feeding on fungi and decaying plant and animal matter, that can be found any time of year. The first was Suillia variegata from 12th March, with the similar Suillia bicolor picked out as new for the Warren on 21st October.

Also waiting to ambush other insects, Thick-headed flies (Conopidae) are well represented on site. First of year was Plain-winged Spring Beegrabber Myopa testacea on 18th May, Ferruginous Beegrabber Sicus ferrugineus from 27th May, Four-banded Beegrabber Conops quadrifasciatus from 25th July, Waisted Beegrabber Physocephala rufipes from 10th August and Ivy Waspgrabber Lopoldius signatus on 8th September.

Four-banded Beegrabber Conops quadrifasciatus - Alan Keatley

One of the more familiar families are the craneflies (Tipulidae). Many of these species favour the damper areas but numbers were reduced on site this year. Nine species were reported, only half the number seen over the last five years. The first cranefly of the year was Symplecta stictica on 28th March, with Tipula vernalis appearing on 28th April. The first of the black and yellow Nephrotoma species, N. appendiculata, emerged on 5th May, followed by N. quadrifaria from 27th June, N. flavipalpis from 22nd July and N. flavescens on 7th October. The two commonest 'Daddy-long-legs' Tipula oleracea and T. paludosa were greatly appreciated by recently fledged Starlings before they emerged from their leatherjackets. Ptychoptera contaminata, one of the similar but unrelated phantom craneflies, was first seen on 15th May.

Tipula confusa - Alan Keatley

Dagger flies (Empididae) were another group much reduced this year with just two species recorded, Empis femorata from 28th April and Empis tessellata from 7th May. Bibionidae flies were represented by Bibio johannis on 14th March, B. lanigerus on 2nd April and the familiar Common Fever Fly Dilophus febrilis and St. Mark's Fly B. marci on 28th April (St Mark's Day is 25th April). 

Stiletto flies (Therevidae) were limited to Coastal Silver-stiletto Acrosanthe annulata from 13th May and Common Stiletto Thereva nobilitata from 6th June.

Snipeflies (Rhagionidae) included the Downlooker Snipefly Rhagio scolopaceus from 11th June, Black Snipefly Chrysopilus cristatus from 29th June and a new species, Little Snipefly Chrysoteuchia culmella on 10th June.

Little Snipefly Chrysoteuchia culmella  - Alan Keatley

House and Stable Flies (Muscidae) recorded included Phaonia subventa from 14th March, P.  tuguriorum from 19th March and the distinctive Noon Fly Mesembrina meridiana from 3rd October.

Noon Fly Mesembrina meridiana - Alan Keatley

Records of Dung flies (Scathophagidae) are usually limited to the predatory Yellow Dung Fly Scathophaga stercoraria, which was recorded in all months, the first of which on 19th January. A Large Mantis Dung Fly Norellisoma spinimanum on 28th September broke the monopoly with Strandline Dung Fly S. litorea another welcome sighting.

    Yellow Dung Fly Scathophaga stercoraria with Muscid prey - Alan Keatley

Blowflies (Calliphoridae) included three common species, the greenbottles Eudasyphoria cyanella and Neomyia viridencens; and the bluebottle Calliphora vicina, the widespread Pouting Woodlouse Fly Rhinophora lepida was added to the year's audit on 20th June. The highlight was another record of the migratory Locust Blowfly Stomorhina lunata on 29th August.

Locust Blowfly Stomorhina lunata - Alan Keatley

Tachinidae are a large family of largely parasitic flies. The few records included a new species, Lypha dubia, a widespread woodland species, on 6th April. Others included Gastrolepta anthracina on 22nd May and the striking, bug-searching Ectophasia crassipennis on 27th July, a further record of this recent arrival.

Ectophasia crassipennis - Alan Keatley

Flesh flies (Sarcophagidae) included a Dark-tailed Grasshopper Flesh Fly Blaesoxipha plumicornis found on 27th June, a new species for the Recording Area. Other sarcophagids recorded were all satellite flies that deposit their eggs in solitary bee and wasp nests. These were Tessellated Satellite Fly Miltogramma germari from 6th June, Silver-fronted Satellite Fly Metopia argyrocephala from 12th June, Mason-wasp Satellite Fly Amobia signata from 24th June and Dark-palped Shadow Fly Sentainia conica on 6th August.

Mason-wasp Satellite Fly Amobia signata - Alan Keatley

Dark-edged Bee-fly Bombylius major were searching for bee nests to deposit eggs from 30th March. Another member of the Bombyliidae family was unexpected, a Dune Villa V. modesta, the first for over 20 years was on Warren Point on 18th July.

Dune Villa V. modesta - Alan Keatley

For the second year there was only one species of Horsefly (Tabanidae) recorded, the fearsome looking Dark Giant Horsefly Tabanus sudeticus. The previously troublesome Notch-horned Cleg Haematopota pluvialis has not been recorded for two years. Their larvae require damp conditions, another species impacted by recent dry summers.

The first hunting Robberflies (Asilidiae) were on wing with Brown Heath Robberfly Machimus cingulatus from 18th May with Violet Black-legged Robberfly Dioctria atricapilla from 20th May, Kite-tailed Robberfly Tolmerus atricapillus from 11th June (the most frequently recorded), Stripe-legged Dioctria baumhaueri, Slender-striped Leptogaster cylindrica and Common Awl Robberfly Neoitamus cyanurus all first seen on 12th June and Dune Robberfly Philonicus albiceps on the late first date of 13th August.

Soliderflies (Stratiomyidae) are mainly found during the summer and early autumn months. The first was a Broad Centurion Chloromyia formosa on 11th June, with a Yellow-legged Black Pachygaster leachii on 29th June a new species for the Recording Area. The similar Dark-winged Black P. atra was first seen on 3rd July. The similar Legionnaires, Dull Four-spined Chorisops tibialis and Bright Four-spined C. nagatomii were recorded from 16th July and on 7th September, respectively. 

Bright Four-spined Legionnaire Chorisops nagatomii - Alan Keatley

A brackish water soldierfly, the Flecked Snout Nemotelus notatus, had a reasonable year but the nationally scarce freshwater Ornate Brigadier Odontomyia ornata was again absent. The year ended as it began with a Centurion, this time Twin-spot Centurion Sargus bipunctatus from 18th September.

Flecked Snout Nemotelus notatus - Alan Keatley

The gall midges (Cecidomyiidae) are best identified by the plant galls caused to feed their larvae. Fourteen species were recorded including Anisostephus betuliinus and Resseliella betulicola on birch leaves, Semudobia skuhravae in birch seeds, Kiefferia pericarpilcola on Wild Carrot flowers, Dasineura ulmaria on Meadowsweet leaves, Wachtliella persicariae on Redshank leaves and Rhopalomyia taneceticola on Tansy flowers. Two new species were discovered, Dasineura acrophila, forming a pod on Ash leaves, on 18th May and Placochela nigripes on Elder flowers on 14th July.

Dasineura acrophila - Kevin Rylands