[For explanations and definitions see here. Almost all of the data here is derived from NBN Atlas and the species information from Steven Falk's Flickr and the HRS website]

May is the first really big month for hoverflies, with 72 species at peak: only June has more. On top of that, a whopping 94 species exceed 10%opa for the first time! It's an important month for Criorhina/Matsumyia, Cheilosia, Brachyopa, Neoascia, Epistrophe, Parasyrphus, Heringia and Pipiza in particular - see the advice on how to photograph 'black jobs' in April's post.

Prominent among the species that are just getting going this month are members of Platycheirus, Chrysotoxum, Parhelophilus, Sphegina and other Brachyopini.

May is the best month to see....

*TOP TARGET*

...Callicera rufa (62,-70%)

A distinctive Callicera, dark with foxy red hair and legs entirely orange except the apical tarsal segements. This species was long known only from Caledonian pine forests, where the larvae inhabit rot holes in Scots pine but in the the last two decades it has begun to pop up all over England! They have also been found in other species of conifer. Falk's pics

*TOP TARGET*

...Brachypalpus laphriformis (42,-96%)

A well built and hairy species similar to Chalcosyrphus eunotus, but with shining scutum and without grey spots on the abdomen. Best found basking on tree trunks and stumps. The larvae develop in decaying tree wood, mainly beech and oak. Falk's pics

*TOP TARGET*

...Cheilosia bergenstammi (19,-97%) and Cheilosia fraterna (28,-95%)

Perhaps surprisingly underrecorded, although they are a little tricky to identify due to their similarity with each other! The following features help to distinguish this pair from other Cheilosia: orange antennae, black eye hairs, and face profile from the side (low facial knob). To distinguish from each other, in bergenstammi the hind leg has an obvious dark ring (fraterna usually doesn't), the scutellum has long marginal bristles (shorter in fraterna), and the body hair of bergenstammi is longer. These are the sorts of features that will get at lot of other Cheilosia to species. bergenstammi is associated with ragwort (jacobaea vulgaris) - the larvae mine the base of the stem. fraterna is associated with marsh thistle (Cirsium palustre). Look for ovipositing females on these plants regardless of whether they are flowering. Falk's pics of bergenstammi and fraterna

*TOP TARGETS*

...Criorhina asilica (49,-92%) Criorhina floccosa (31,-62%) and Matsumyia berberina (24,-87%)

Bumblebee mimics with a pointed face and distinctive shaped antennae. HRS still includes berberina in Criorhina. A good view of the tufts of hair on the side of the thorax is useful. These species are associated with rotting stumps of deciduous broadleaved trees. They can sometimes be found resting on the underside of leaves at a good height. Falk's pics

...Dasysyrphus venustus (19,-96%)

This is one of a group of quite difficult species to identify (well... all the Dasysyrphus except albostriatus and tricinctus). If you see a Dasysyrphus with the distinctive long dark Dasysyrphus stigma, and the curvy spots of this group it helps to show clearly whether the abdominal bands reach the margin, how extensive the face stripe is, the dusting on the frons, and if possible the underside of the abdomen. It can be found visiting a variety of flowers (Falk suggests in particular, buttercups, umbellifers and rowan). Falk's pics

...Melangyna arctica (54,-100%)

Similar to M lasiophthalma but less hairy. As with all Melangyna, try to get a good image of the scutellum (yellowish centre, with dark hind edge and corners). To distinguish from M lasiophthtalma and M ericarum, it helps to see the dark halteres, and the frons which is strongly dusted but the dust is darker than on the face. In males the hair on the scutum is black. Larvae are known to feed on the common alder aphid Pterocallis alni - so watch out for it around alder trees. Recent records suggest it has disappeared from the south east, it now occurs in Britain north and west of the Fosse Way (seriously... a diagonal line from Lincoln to Exeter!). Falk's pics

...Heringia latitarsis (75,-100%)

One of the few identifiable Heringia in photos, just - but you need a male and a good shot of the front leg. It's also very rare. The male has quite a strongly expanded front basitarsus. England and Wales. Larvae are associated with poplar aphids, but not exclusively. Falk's pics

...Platycheirus manicatus (9,-92%) and Platycheirus tarsalis (32,-78%)

It's hard to know why these species are quite so underrecorded. manicatus is one of the easiest Platycheirus to identify, with its snouted face, large spots and heavily dusted frons and scutum. It is very common everywhere. tarsalis is another snouted species, distinguished by the size of the markings and extent of dusting, as well as the number of expanded segments in the male foretarsi.

Their long mouthparts mean that they can feed on some tubular flowers that are not favoured by most hoverflies, such as ground-ivy and bluebells. Larvae are usually found in low vegetation: In general, low vegetation and long grasses are good places to look for Platycheirus. Falk's pics of manicatus and tarsalis

...Brachyopa bicolor (70,-100%), Brachyopa insensilis (60,-48%), Brachyopa pilosa (54, -100%) and Brachyopa scutellaris (38, -92%)

It is the month of Brachyopa - all four species at peak. The colour of the scutellum and the humeri (front corners of the thorax) are useful. The real clincher is the inside face of the antennae - a very hard shot to get in the field, but if you have a good macro camera give it a go! Half the problem is recognising them as hoverflies!

Brachyopa are stongly associated wth sap runs in old trees - which is where the larvae live. bicolor is most associated with Beech and Oak, and occurs south of Leeds (although its range is apparently expanding rapidly). insensilis used to be associated with elms until Dutch elm disease, but seems to have made the switch to horse chestnut - bringing it into more urban areas. pilosa is found south of Leeds and in the Cairngorms area: in Scotland it prefers aspen, poplar and birch, elsewhere it prefers oak and beech. scutellaris occurs throughout Britain and has a wide taste in trees Falk's pics

...Orthonevra brevicornis (44,-98%), and Orthonevra geniculata (45,-98%)

More black jobs... Wings and face will get you the genus, a good (side) view of the antennae and legs in addition will get you the species. brevicornis has normal-shaped antennae, the other three species have a very long final antennal segment. geniculata has partly yellow legs - a feature only shared with intermedia which is confined to Cheshire/Liverpool/Manchester - but geniculata has a stigma that is basally dark and an infuscated crossvein r-m (all pale stigma and uninfuscated r-m in intermedia). (The fourth, and commonest species, nobilis is identified by the combination of elongate antennae and black legs)

Apart from intermedia, British Orthonevra can be found all over Britain. They are associated with wetlands, fens, peat, carr etc. Falk's pics (no intermedia)

Eristalis abusiva (16,-98%)

This species closely resembles E arbustorum so everything here will also improve your ID rate on that common species. I wrote a guide on how to distinguish them here. It is important to get the middle tibia from the side (not black at the tip like arbustorum), and the face.

This species can occur anywhere but is commonest near the coast. Coastal grazing marsh is popular with it - look near muddy pools - and it likes to nectar on umbellifers and asters, including sea aster. Falk's pics

The following species were discussed in April's's 'First month you may find', but they peak now:

Chalcosyrphus eunotus (60,-95%), Cheilosia chrysocoma (53,-79%), Cheilosia pagana (11,-73%), Ferdinandea cuprea (18,-40%), Neoascia meticulosa (27,-95%), Neoascia obliqua (49,-95%), Pocota personata (66,-94%), Meligramma cincta (41,-52%), Parasyrphus malinellus (63,-100%), Pipiza luteitarsis (49,-86%)

Other species that peak in May [species in square brackets usually require microscopy to identify]:
Eristalinae Anasimyia interpuncta (62,-100%)
Caliprobola speciosa (68,-100%)
Cheilosia variabilis (20,-78%), [Cheilosia albitarsis (11,-99%), Cheilosia antiqua (33,-100%), Cheilosia barbata (55,-100%), Cheilosia griseiventris (73,-100%), Cheilosia lasiopa (57,-96%), Cheilosia nigripes (82,-100%), Cheilosia pubera (59,-100%), Cheilosia ranunculi (61,-100%), C. semifasciata (42,-100%), C. urbana (53,-100%), C. uviformis (95,-100%)]
Eristalis similis (88,+155%)
[Heringia heringi (64,-72%), H. pubescens (76,-100%), H. senilis (92,-100%), H. verrucula (85,-100%)]
Leucozona lucorum (8,-50%)
Portevinia maculata (23,-66%)
Psilota anthracina (79,-80%)
Rhingia campestris (2,-71%)
Xylota abiens (67,-100%)
Syrphinae Baccha elongata (13,-32%)
[Dasysyrphus hilaris (79,-82%)]
Epistrophe eligans (10,+45%), E. melanostoma (92,+473%), E. nitidicollis (53,-25%), E. ochrostoma (100,-100%)
Epistrophella euchroma (77,36%)
Melanostoma scalare (2,-48%)
Meligramma trianguliferum (61,-26%)
Parasyrphus nigritarsis (62,-84%)
Platycheirus sticticus (73,-100%), P. splendidus (55,-93%)
Sphaerophoria bankowskae (95,-100%)
Syrphus nitidifrons (100,-100%)
Xanthogramma citrofasciatum (43,-47%)
Pipizinae [Pipiza bimaculata (85,-100%), P. noctiluca (25,-93%), P. notata (51,-100%)]

May may be the first month you see...

...Hammerschmidtia ferruginea (74,-100%)

33%opa in May. If you live in or visit Strathspey in May or June that is where this large, unique and critically endangered hoverfly lives. You have a genuine chance of seeing it in the area between Grantown-on-Spey and Kingussie. It looks a bit like a Brachyopa, but larger and redder. It is associated with the rotting trunks/stumps of fallen aspen trees, but needs a significant area of aspen woods (about 4.5ha to thrive). Smaller woods are much less likely to yield the species. Falk's pics

*TOP TARGETS*

...Parhelophilus consimilis (55,-100%) , Parhelophilus frutetorum (37,-93%), Parhelophilus versicolor (33,-100%)

53%opa, 38%opa, and 59%opa in May respectively. It is difficult to get this genus to species. A good view of the front tibia will get you consimilis (black at the tip); your best bet for the other two is to get a low angle on the hind tibia - male frutetorum have a prominent tubercle at the base of the underside of the hind femur, versicolor does not. Remember, male Parhelophilus have well-separated eyes!

frutetorum does not occur in Scotland, the others occur everywhere. consimilis is easily the rarest. They are wetland specialists; consimilis is a particular fan of bogs and poor quality fen. Falk's pics

*TOP TARGET*

...Brachypalpoides lentus (36,-79%)

81%opa in May. Looks like a Xylota, or Chalcosyrphus, but the legs are entirely black and the abdomen mostly blood-red. The only other species with this combination is Chalcosyrphus piger, which was only added to the British list from Suffolk in 2021 - so take extra care there (the abdomen of C. piger is red to the tip - black at the tip in B lentus). Xylota segnis looks similar, but the band on the abdomen is smaller and more orange, and the legs are partly pale.

B lentus can be found anywhere in Britain, with NW England from Cheshire to Cumbria being a particular hotspot. Found flying through low undergrowth, larvae develop in rotting heartwood of living trees - especially Beech, and also perhaps oak. Look for trees with rot exposed close to the ground. Falk's pics

*TOP TARGETS*

...Lejogaster metallina (12,-96%), and Lejogaster tarsata (36,-97%)

39%opa and 27%opa respectively in May. As with other 'black jobs' in Brachyopini the face helps enormously to confirm the genus. In this case the shape and colour of the antennae are also crucial for the species determination. These are wetland species that are fond of buttercups. Both occur widely across Britain. Falk's pics

*TOP TARGET*

...Pipiza austriaca (40,-92%)

25%opa in May. This Pipiza is identifiable in both both sexes with a low angle on the hind femur. The hind femur is swollen, with a noticable ridge on the underside. Larvae feed on aphids, often on hogweed. According to Falk it is usually encountered on buttercups and umbellifers in meadows and at woodland edge. Falk's pics.

...Cheilosia impressa (25,-81%)

47%opa in May. A Cheilosia with yellow wing bases and entirely black legs, the eyes are also more brightly red than the C albitarsis complex, which also have yellow wing bases (but not entirely black legs - yellow forebasitarsi). Found around scrub and woodland edge, the adults are especially fond of umbellifers, the larvae mine the stems of burdock plants, so look for ovipositing females there. found all over the UK, but primarily in England and Wales.

...Microdon analis (70,-84%) and, Microdon devius (52,-100%)

61%opa and 16%opa respectively in May. These are the two species of Microdon with black rather than orange scutellum. They are distinguished by the color of hairs on the back half of the scutum - this feature is best photographed a little from the side, top down photos don't often show hair colour well.

These species are very restricted in range: analis is known from parts of the Highlands and Cairngorms, the area around Loch Linnhe and the Isle of Mull, as well as a triangle between Poole harbour, Oxford and London. devius is known in areas just south of London and towards the Solent (with a hotspot in the Surrey hills west of Dorking), another line from Oxfordshire east through the Chilterns, in East Anglia between Thetford and Eye, and in north-west Wales along the rivers Dwyryd and Mawddach. Both species are associated with heathy woodland, although devius also likes chalky grassland. They do not visit flowers but can be seen on low vegetation. M analis develop in the nests of black ants in the genus Lasius near rotting timber, whereas M devius prefers the distinctive nest mounds of the Yellow Field Ant Lasius flavus. The larvae look like hemispherical daleks... they're quite cool. (Incidentally the other two species can only be identified to species as larvae! They occur south of the M4, in the south-west peninsula, Wales and west Scotland from north of Glasgow to Mallaig - especially the Isle of Mull) Falk's pics

...Platycheirus

Twelve species of Platycheirus exceed 10%opa for the first time in May - including many of the clypeatus and peltatus groups (see list below). As clear a view of the abdomen and the legs - especially every part of the male front leg, is vital. Grassy wetland areas are a common theme, though P europeaus prefers woodland (especially with conifers); P. immarginatus prefers brackish habitats, saltmarsh, coast and tidal estuary, likes to visit sea clubrush, sea lavenders and sea couch; other meadow-like habitats are also frequented. They are good candidates for sweeping long grasses with a net. Falk's pics

...Chrysotoxum arcuatum (22,-81%) , Chrysotoxum cautum (34,-53%), Chrysotoxum elegans (51,-97%)

86%opa, 81%opa and 18%opa respectively in May. A low side angle provides easy identification of male cautum because of the large genitalia. In general with Chrysotoxum get the clearest photo of the antennae you possibly can - ideally from the side - so that the relative sizes of the segments can be seen. for some species the details of the abdomen pattern are useful - especially towards the sides. Undersides can also help.

Draw a line from the Humber to the Severn estuaries and you will find cautum below it and arcuatum above it (with a bit of mixing in the middle, and cautum also in south Wales). elegans is strongly coastal from Pembrokeshire to Portsmouth, but also occurs in the Surrey Hills and East Anglia around Thetford. They tend to occur in grassy areas, and tend to fly low and fast. Falk's pics

Eupeodes bucculatus (63,-100%), Eupeodes nielseni (73,-100%), Eupeodes nitens (69,-100%)

50%opa, 88%opa and 43%opa respectively in May. If you see a female Eupeodes with the frons too black for luniger but too dusted at the sides for latifasciatus it may be one of these. It is easier to ID females. They are quite dark species: in nitens and neilseni the sides of the fifth tergite are almost entiely black, and female neilseni have an entirely black hind femur. With all Eupeodes it is valuable to show the abdomen pattern right to the edge, the female frons and face, and the underside is particularly useful if you can get it. Falk's pics

Other species exceeding 10%opa for the first time in May are [species in square brackets usually require microscopy to identify]:

Pipizinae [Pipizella viduata (17,-99%) 25%opa, P. virens (42,-98%) 37%opa]
Trichopsomyia flavitarsis (26,-99%) 14%opa
Microdontinae [M. myrmicae (63,-62%) 81%opa]*
Eristalinae Anasimyia lineata (21,-83%) 33%opa, A. lunulata (46,-98%) 14%opa, A. transfuga (47,-98%) 26%opa
Chalcosyrphus nemorum (23,-80%) 80%opa
Cheilosia illustrata (7,-29%) 16%opa, C. soror (45,-44%) 15%opa, [C. vicina (47,-100%) 22%opa, C. vulpina (47,-93%) 69%opa]
Chrysogaster virescens (41,-100%) 48%opa
Eristalinus sepulchralis (14,-67%) 29%opa
Eristalis arbustorum (3,-41%) 22%opa, E. horticola (10,-56%) 36%opa, E. nemorum (9,-24%) 40%opa
Eumerus sabulonum (51,-100%) 22%opa, [E. strigatus (30,-99%) 50%opa]
Helophilus hybridus (16,-63%) 38%opa, H. pendulus (0,-24%) 39%opa
Melanogaster aerosa (58,-100%) 14%opa, M. hirtella (9,-97%) 31%opa
Merodon equestris (10,+169%) 55%opa
Myathropa florea (4,+174%) 50%opa
[Myolepta dubia (71,-74%) 10%opa, M. potens (92,-100%) 50%opa]
[Neoascia geniculata (39,-98%) 70%opa, N. tenur (5,-99%) 32%opa]
Orthonevra nobilis (32,-90%) 15%opa
Riponnensia splendens (26,-70%) 24%opa
Sericomyia lappona (23,-77%) 88%opa, S. silentis (3,-48%) 11%opa
Sphegina sibirica (35,-92%) 24%opa, [S. clunipes (20,-100%) 39%opa, S. elegans (33,-94%) 13%opa, S. verecunda (36,-99%) 24%opa]
Syritta pipiens (2,-37%) 25%opa
Tropidia scita (15,-71%) 44%opa
Volucella bombylans (5,-42%) 18%opa, V. inflata (31,-38%) 31%opa
Xylota jakutorum (29,-91%) 17%opa, X. segnis (4,-43%) 60%opa, X. sylvarum (17,-41%) 12%opa, Xylota tarda (68,-100%) 27%opa
Syrphinae C. octomaculatum (87,-100%) 25%opa, C. vernale (85,-72%) 50%opa
Dasysyrphus friuliensis (80,-100%) 57%opa, D. neovenustus (87,-68%) 14%opa
Didea intermedia (65,-83%) 35%opa
Epistrophe diaphana (59,-96%) 43%opa
Episyrphus balteatus (0,45%) 14%opa
Eupeodes corollae (6,39%) 19%opa
Megasyrphus erraticus (58,-88%) 50%opa
Melanostoma mellinum (3,-88%) 48%opa
Paragus albifrons (85,-100%) 33%opa, [P. haemorrhous (18,-97%) 31%opa]
Parasyrphus lineola (57,-73%) 81%opa, P. vittiger (48,-97%) 31%opa
Platycheirus amplus (83,-100%) 20%opa, P. angustatus (14,-99%) 30%opa, P. aurolateralis (88,-100%) 33%opa, P. clypeautus (8,-99%) 37%opa, P. europaeus (40,-100%) 46%opa, P. fulviventris (29,-97%) 25%opa, P. immarginatus (48,-100%) 20%opa, P. nielseni (37,-100%) 19%opa, P. occultus (29,-99%) 28%opa, P. peltatus (22,-96%) 74%opa, P. podagratus (46,-100%) 36%opa, P. scambus (31,-96%) 25%opa
Pyrophaena granditarsis (7,-93%) 13%opa, P. rosarum (15,-90%)
27%opa
Scaeva selenitica (37,-9%) 19%opa
Sphaerophoria rueppellii (44,-64%) 17%opa, S. scripta (5,+25%) 14%opa, [S. batava (53,-100%) 27%opa, S. fatarum (58,-96%) 28%opa, S. interrupta (56,-96%)
30%opa, S. philanthus (22,-100%) 27%opa, S. taeniata (65,-100%) 23%opa]
Xanthogramma pedissequum (18,+26%) 41%opa

Posted on February 7, 2024 11:46 PM by matthewvosper