Tuesday, 5 January 2021

Wildlife Review 2020: Flies

Hoverflies

A total of 43 species of hoverfly were recorded compared with 54 seen in 2019. Several regular species of the genus Cheilosia and Platycheirus, that are mostly prevalent in Spring, were not seen this year.

The first hoverfly of the year was a Common Dronefly Eristalis tenax in February, followed by Tapered and Plain-faced Dronefly Eristalis pertinax arbustorumMarmalade Hoverfly Episyrphus balteatus and Platycheirus scutatus by early March.

Some hoverflies are highly migratory and numbers can be noticeably boosted by influxes. On 13 June hundreds of Marmalade Hoverfly were on site with lesser numbers of White-clubbed Hoverfly Scaeva pyrastri. By mid August other migrant hoverflies such as Large Tiger Hoverfly Helophilus trivittatus and Syritta pipiens had begun to arrive, sharing Water Mint and Common Fleabane with Batman Hoverfly Myathropa florea, Hornet Hoverfly Volucella zonaria and Giant Pied Hoverfly Volucella pellucens

White-clubbed Hoverfly - Alan Keatley

Other nectaring hoverflies seen at this time included Common Tubetail Sphaerophoria scripta, Humming Syrphus Syrphus ribesii, Tiger Hoverfly Helophilus pendulus and Stripe-faced Dronefly Eristalis nemorum.

Common Tubetail - Alan Keatley

Only one new species was recorded this year, Rural Bulbfly Eumerus strigatus on 12 September. Although there was a lack of new species, several hoverflies confirmed their continuing presence following their first occurrence in 2019. 

These included Hook-banded Wasp Hoverfly Chrysotoxum festivum, Common Thistle Cheilosia Cheilosia proxima and Parsley Cheilosia Cheilosia pagana in June,  Broad-banded Epistrophe Epistrophe grossulariae and Golden-tailed Hoverfly Xylota sylvarum in July, Lesser Hornet Hoverfly Volucella inanis in August and Yellow-barred Peat Hoverfly Sericomyia silentis in September.

Golden-tailed Hoverfly - Alan Keatley

Throughout October hoverflies species started to dwindle, although Common Dronefly were still plentiful on bramble and ivy until the end of the month. By November hoverfly numbers had dropped off considerably with just single sightings of Melanostoma scalare on 19th, Common Spotted Field Syrph Eupeodes luniger and Humming Syrphus on 21st, and Marmalade Hoverfly on 26th. The last hoverfly of 2020 was a Glass-winged Syrphus Syrphus vitripennis on 19th December.

Marmalade Hoverfly - Alan Keatley

Dawlish Warren: Hoverflies


Other flies

Including one hoverfly, 11 fly species were added to the Warren list in 2020 bringing the overall total to 645 species. 

The first new fly of the year was the cranefly Cylindrotoma distinctissima on 20 June. Less obvious, but still new for site were gall midges Contarinia hyperici (St John's-wort), Cystophora sonchi (sow-thistles), Jaaplella schmidti (plantains) and the leaf miners Chromatomyia ramosa (Teasel), Aulgromyza heringii (Ash) and Phytomyza agromyzina (Dogwood) all given away by their larval stages on specific plants. The other new species included the smart Looped Flutter-fly Palloptera muliebris in the Cuckoo's Nest on 27 August.

Prior to this year there were only three records of the migratory Locust Blowfly Stomorhina lunata on site, but between 1-22 October there were a further five individuals. The occurrence of this North African vagrant coincided with strong southerly winds.

Locust Blowfly - Alan Keatley

A cross section of more regular species this year included White-tipped Semaphore Fly Poecilobothrus nobilitatusCoastal Silver Stiletto Acrosathe annulataMarsh Snipefly Rhagio tringariusField Buff Snail-killer Tetanoceta elataSlender-striped Robberfly Leptogaster cylindrica, the soldierfly Black-horned Gem Microchrysa politaFour-banded Bee-grabber Conops quadrifasciatus and the peculiar looking ladybird mimic, Graphomya maculata.

Field Buff Snail-killer - Alan Keatley

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