[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]

March is the month that hoverflies begin to get going. It's not exactly a bumper month (just 13 species in total qualify to be covered in this post), but hoverflies will get increasingly common and diverse as the month progresses - depending on the weather. Look especially at any Prunus species in flower - blackthorn is a particularly popular plant. But also inspect catkins and don't neglect common weeds like dandelions! There are a few underrecorded early Spring specialists to look out for though... many of these species are small elongate species like Melangyna, Melanostoma and Platycheirus.

March is the best month to see....

*TOP TARGET*

...Melangyna quadrimaculata (58,-72%)

This is the one and only UK hoverfly that actually peaks in March (so I've gone to town on it a bit!). This species can sometimes even be seen in February, and it remains abundant in April before almost disappearing. The species is underrecorded in iNatUK by 72% compared to the NBN database, and 58th centile for rarity, so quite a challenge but well worth looking for! Records are spread widely if patchily across the whole of Great Britain.

How to identify... You can see RG iNat observations here (inc. international) and Steven Falk's fabulous resource here. It is a thoroughly strange species for Syrphini due to its basically black scutellum and face; it is easily mistaken for a Platycheirus. Males have four obscure spots (as suggested by the scientific name) arranged as a pair on each of T3 and T4. Female abdomens are entirely black. The wing stigma is very long and black - reminicent of Dasysyrphus. The scutum bears long golden/pale hairs. The eyes are distinctly hairy. The legs and antennae are completely black.

Similar species...
 Platycheirus males have modified forelegs, usually have spots on T2, coloured parts to the legs and bare eyes. The long black stigma of M quadrimaculata should also help to separate.
 Cheilosia species are not so elongate, the head does not hug the thorax like in Syrphinae, and there are zygoma on the face. Some have orange antennae. None have a similar stigma.
 Melangyna barbifrons is a similarly dark Melangyna that begins to occur a little in March and peaks suddenly in April. The eyes are not hairy, and the hairs on the male scutum are mostly black. Males have the same arrangement of spots as quadrimaculata but females have paired spots on all of tergites 2-4. The stigma is apparently much paler.

How to find...

Larvae apparently feed on adelgids (woolly-aphid-like creatures) associated with fir trees. So you need to be in an area with some conifers. If you see woolly material on a conifer, you might therefore encounter an ovipositing female. Adults can be found attending the catkins of Salix and hazel trees (though it might be worth checking other catkins too), they may also attend blackthorn flowers - one of the best plants for finding early hoverflies generally.

March may be the first month you see...

*TOP TARGETS*

...Cheilosia grossa (38,-59%) and Cheilosia albipila (44,-79%)

88% and 39% of peak abundance (%opa) in March respectively. Large, furry and distinctive Cheilosia species. When photographing furry Spring Cheilosia try to get the colour of the antennae and the femora. albipila has orange antennae and the female has entirely orange legs (black antennae and femora in grossa). Neither species has a wing cloud. Both species can be found anywhere in Great Britain. The larvae of grossa mine thistle stems, especially spear thistle, so look for ovipositing females at the base of these plants (not just nectaring on the flowers), adults nectar on a variety of flowers. albipila larvae mine marsh thistle stems, and are therefore associated strongly with wetlands. Here are Falk's pictures of albipila and grossa

...Platycheirus discimanus (85,-43%)

33% of peak abundance (%opa) in March. A grey spotted species. In males the foretibia is not expanded (unlike albimanus) - only the first two foretarsi are expanded into a disc shape: all other species like this have yellow spots. The male frons is quite broad. The female frons is broader than in albimanus and lacks the small lateral dusting of albimanus. The female fore- and mid- femora are black (yellow, sometimes darkly, in albimanus), and the female abdomen is spotted (banded in ambiguus). Most easily identified from males, but you need a good shot of the front feet! Found throughout Great Britain. Visits blackthorn blossom. Very rare though - would be a superb find! Falk's pics

...Eristalinus aeneus (30,-51%)

30%opa in March, although it doesn't peak until July, and can be found as an adult even in the winter. Eristalinus have unique spotty eyes. aeneus is a large species in which eye hairs are missing from the lower part of the eyes, and the scutum normally lacks distinct dust stripes. Males are easily identified because the eyes are connected as normal in hoverflies (not so in E sepulchralis). This is a coastal species; larvae live in brackish pools and may feed on rotting seaweed. Falk's pics

...Melangyna lasiophthalma (25,-81%)

28%opa in March. A common species, but quite underrecorded on iNat. It is widely distributed throughout the British Isles. It has a normal Melangyna pattern with three pairs of yellow spots, but it is hairier than most Melangyna. Be sure to get a good photo of the scutellum, and/or the female frons. The scutellum is mainly yellow, but has significantly black corners and the hind margin is narrowly black. The female frons has small dust spots compared to other well-marked species. See Falk's pictures. It can be found on Salix catkins and Prunus blossom, or basking on sunlit tree trunks.

...Syrphus torvus (13,-68%)

19%opa in March. High quality pictures of the eyes are required to show eye hairs, especially in females. Falk's pics

...Criorhina ranunculi (35,-71%)

15%opa in March. An impresssive bumblebee mimic which is quite easily identified and can be found anywhere in Great Britain. Get a good view of the antennae/face and the wing venation if possible. This species peaks in April and is rarely seen by June, it is most likely to be confused with Volucella bombylans, becuase it shares the pointy yellow face, but that species does not appear until May. Volucella species have an incurved upper-outer cross vein, and the antennae are distinctly different. C ranunculi has long pale hairs on the scutellum contrasting with a completely black-haired scutum: this combination would be most unusual in V bombylans. It could also be confused with Eristalis intricaria, but that has a loop in the radial vein, and lacks the pointy yellow face. Male C ranunculi have a swollen hind femur which separates it from both of the above species.

It hovers territorially to defend patches of blossom and is aggressive towards other insects. It prefers broadleaved wooded areas. Prunus species are popular, but it can also be found on catkins. It may be found resting on the undersides of leaves above head height or on tree trunks. Females may be seen ovipositing near the base of living trees suffering heart-rot. Falk's pics

...Melangyna barbifrons (75,-100%)

13%opa in March. See above for differentiation from M quadrimaculata. Very rare. There are no observations of M barbifrons on iNat anywhere in the world, but Falk has pictures of a female and a male from Norway is shown here. NBN and HRS maps differ slightly, but both show a wide distribution throughout the island of Great Britain. Falk's pics

Other species exceeding 10% of peak abundance (%opa) for the first time in March are [species in square brackets usually require microscopy to identify]:
Meliscaeva auricolis (15,+63%) 12%opa,
Parasyrphus punctulatus (30,-68%) 11%opa,
Eristalis tenax (1,+91%) 15%opa, E. pertinax (1,+57%) 14%opa

Posted on February 7, 2024 11:01 PM by matthewvosper