Thursday 28 December 2023

Wildlife Review 2023: Hoverflies

Hoverflies (Syrphidae) represent a common and distinctive family of true flies (Diptera);  many are readily identifiable with their distinctive markings. As such, they have their own section in the wildlife review.
A better year with 54 species, compared with 51 in 2022, but down from 61 in 2021, summer droughts impacting a number of species. One new species was recorded; a Migrant Flat-belly Xanthandrus comtus on 12th August.
The hoverfly year started with early records of Common Dronefly Eristalis tenax on 5th January and Tapered Dronefly E. pertinax on 26th February. The latter is mainly a spring hoverfly on site and males can be seen defending their territories on warmer days, whereas Common Dronefly can be found throughout the year with a peak in late summer and autumn.

Common Dronefly Eristalis tenax - Alan Keatley
Spring hoverflies began to appear with Marmalade Hoverfly Episyrphus balteatus and Humming Syrphus S. ribesii on 12th March. Both have a long flight season with sightings up to November; numbers were down with fewer migrant influxes of Marmalade Hoverfly this year.

Marmalade Hoverfly Episyrphus balteatus - Alan Keatley

March continued with Common Spotted Field Syrph Eupeodes luniger on 18th, Common Thistle Cheilosia C. proxima on 25th, Hairy-eyed Syrph Syrphus torvus on 28th, with the first of many Tiger Hoverfly Helophilus pendulus and the equally common Slender Melanostoma M. scalare on 30th. The partial migrant Common Twist-tail Sphaerophoria scripta also made an appearance on 30th, but numbers were down this year.

Hairy-eyed Syrph Syrphus torvus - Alan Keatley
Both generations of Stripe-backed Fleckwing Dasysyrphus albostriatus were represented with a spring sighting on 7th April and an autumn sighting on 14th September. The first truly spring hoverfly; Spring Epistrophe E. eligans was found between 18th April and 1st May. The first Grey-spotted Boxer Platycheirus albimanus was sighted on 20th, these small hoverflies frequent the more wooded areas of the Warren and are commonly seen near nettles. Stripe-faced Dronefly Eristalis nemorum, another common hoverfly; were pairing up, with males characteristically hovering above feeding females from 25th.

Stripe-backed Fleckwing Dasysyrphus albostriatus - Alan Keatley
May is the peak month for early year hoverflies with thirteen species added to the year's audit. Largely foraging around woodland edges were Narcissus Fly Merodon equestris on 13th; Batman Hoverfly Myathropa florea on 15th; Dumpy Melanostoma M. mellinum on 16th; Fluffy Dronefly Eristalis intricaria and Superb Anthill Hoverfly Xanthogramma pedissequum on 18th; Bumblebee Volucella bombylans and Pied Plumehorn V. pellucens on 28th and Hornet Plumehorn V. zonaria on 30th.

Narcissus Fly Merodon equestris - Alan Keatley

Favouring the meadows were from Migrant Field Syrph Eupeodes corollae and Pipizella viduata on 7th; Rural Lesser Bulb Fly Eumerus strigatus on 18th; the migratory White-clubbed Hoverfly Scaeva pyrastri on 27th and Meadow Boxer Platycheirus peltatus on 30th.
Into June and July and attention switches to flowering umbellifers. New species were attracted to these flowers through the months with Burdock Blacklet Cheilosia impressa and Common Pipiza P. noctiluca on 1st June; Glass-winged Syrph Syrphus vitripennis on 3rd; Broad-banded Epistrophe E. grossulariae and Golden-tailed Hoverfly Xylota sylvarum on 12th.

Golden-tailed Hoverfly Xylota sylvarum - Alan Keatley

Later in June, Bumblebee Blacklet C. illustrata on 22nd and on 24th, Bolete Blacklet C. scutellata. July additions were on 3rd, Dark-winged Chrysogaster C. solstitialis on 3rd and Parsley Blacklet C. pagana on 8th.

Bolete Blacklet Cheiliosa scutellata - Alan Keatley
Other summer hoverflies frequented flowering Ragwort and Water Mint with Broad-barred Fleckwing Dasysyrphus venustus and Small Spotty-eyed Dronefly Eristalinus sepulchralis on 1st June, Ragwort Blacklet Cheilosia bergenstammi on 18th July, Spotted Meliscaeva M. auricollis on 20th July, Wasp Plumehorn Volucella inanis on 25th July, and on 27th Common Paragus P. haemorrhous and first of many Compost Hoverfly Syritta pipiens.

Compost Hoverfly Syritta pipiens - Alan Keatley
The wasp mimic; Hook-banded Wasp Hoverfly Chrysotoxum festivum was found on 3rd August and on 12th the Migrant Flat-belly. Gossamer Hoverfly Baccha elongata and Plain-faced Dronefly Eristalis arbustorum were first seen on 13th August, with Marsh Tiger Hoverfly Helophilus hybridus on 23rd and Riponnensia splendens on 29th.

Hook-banded Wasp Hoverfly Chrysotoxum festivum - Alan Keatley
In September, new species were often favouring Common Fleabane. Yellow-barred Peat Hoverfly Sericomyia silentis made its annual appearance from nearby heathlands on 5th, with Stripe-winged Dronefly Eristalis horticola on 7th, the migrant Large Tiger Hoverfly Helophilus trivittatus on 8th and Orange-belted Hoverfly Xylota segnis on 9th.
Into October and attention shifted to flowering Ivy with many hoverflies still active. Leading the way were numerous Marmalade Hoverfly, Common Dronefly and Humming Syrphus. A Pale-knobbed Didea D. fasciata on 10th October was the last addition for the year. Other species still active included Batman, Tiger and Large Tiger Hoverfly, Glass-winged Syrph, Common Twist-tail, Migrant Field Syrph, White-clubbed Hoverfly and a late Hornet Plumehorn.

Hornet Plumehorn Volucella zonaria - Lee Collins

On warmer days in November hoverflies could still be found with Common Dronefly and Marmalade Hoverfly the most numerous. A few overwintering Common Dronefly were still active into mid December on the ornamental Hebe. 

White-clubbed Hoverfly Scaeva pyrastri - Alan Keatley

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