Narcissus Fly

Hunting in the garden for Hoverflies again. Found what I think is Meredon equestris a bumblebee mimic that also exhibits polymorphism and has at least four named variants and multiple examples with mixed characteristics. All very exciting although I don't think my wife was over impressed. It is also known by a number of common names Narcissus Bulb Fly, Greater Bulb Fly, Large Bulb Fly, Large Narcissus Fly.


The four named variants are Batesian mimics of different bumblebee species. This one probably closest to variant narcissi and would I assume pass as a Buff-tail or White-tail Bumblebee. We may not be completely fooled by its appearance but we cannot know what the predator sees and reacts to and the evidence does seem to show that Batesian mimicry does work.


Interesting though that the different variants must recognise each other as being of the same species as they still interbreed and give rise to the multiple examples with mixed characteristics.


Fortunately, as a species, it has a distinctive wing loop in vein R4+5 which can be seen in the picture below. Only one other British hoverfly exhibits this wing pattern and that one can be eliminated on leg colour.


As a bee mimic it is quite effective. The eyes are a bit of a give away but it's robust behaviour and flight pattern gave more of an impression of a bee than of a hoverfly and it had to be seen close up to confirm what it was. Listen out for the buzzing it makes, it is at a  higher pitch than the bees, making it a little easier to spot.

Merodon equestris

Now for something a little less complicated. White markings on black makes the Scaeva pyrastri below one of the easier hoverflies to identify. It is a migratory species with numbers variable from year to year.

Scaeva pyrastri

Scaeva pyrastri

The next is a Sphaerophoria of which there are eleven British species. Six of these have matched spots on the abdomen with the other five being banded as with this specimen. Given the body looking longer than the wings this looks like Sphaerophoria scripta which also happens to be the commonest and most widespread of the eleven species. Also referred to, for obvious reasons, as the Long Hoverfly.

Sphaerophoria scripta  Female

To confuse matters Sphaerophoria.scripta can also present with darker colours and matched abdominal spots which are the result of temperature variations particularly in the earlier spring specimens.

Sphaerophoria scripta  Male

There is only one British species of Syritta and with nothing looking similar the Syritta pipiens below is another hoverfly that is easy to identify. It is small and dark with a slender abdomen but the key feature is the greatly enlarged hind femora. There was a better picture of one of these in my 11 June blog but this one shows the markings on the abdomen which were not clear in that earlier picture.

Syritta pipiens

The example below shows whiter spots on the abdomen. Possibly an older and more faded specimen. Note also the two white triangles on the thorax just behind the head, a key identifier, these also appear to be faded.

Syritta pipiens

As the year moves on I am coming across a few new hoverflies. Below is Meliscaeve cinctella a new one for me and a bit unexpected in the garden as it is a woodland species. I checked the identification a couple of times and am reasonably confident. It is a widespread species and does occur in large numbers some years.

Meliscaeve cinctella

I have also included another picture Myathropa florea. This one a robust looking specimen and displaying a nice example of the "Batman" markings on the thorax.

Myathropa florea

The next hoverfly is probably a new one for me. It is certainly an Eristalis and in this case I think it is Eristalis arbustorum the Plain-faced Dronefly. The dark markings do not extend along the rear of Tergite two to enclose the yellow spots as seen on other members of the genus and there are no dark markings across the centre of the wings as found on E.horticola. It looks good but not a certainty.

Eristalis arbustorum - Plain-faced Dronefly 

The next one I have photographed before. Helophilus pendulus, known as the Sunfly or Tiger Hoverfly. It is unusual in that both male and female have the eyes separated on the head. To tell the sex of the specimen you need to look at the shape of the rear end which unfortunately in this case is not clear in the picture.

Helophilus pendulus 

The final specimen is Volucella pellucens - Large Pied-hoverfly. Again one I have photographed before but it is always a nice one to find.

Volucella pellucens - Large Pied-hoverfly