Hoverfly heaven: summer in a suburban garden

Over the summer I've written a fair amount about the bee species found in our garden - from general bee diversity to a more detailed description of the behaviour of a single, relatively uncommon species. Much of this relates to our attempts to make our garden bee-friendly by providing bee-logs, a wide range of nectar sources and in general a suitably diverse structure. Of course, features like this attract other species groups too and one of these is the hoverflies (Diptera, Syrphidae) which can often be seen visiting flowers.

A 'typical' hoverfly showing yellow and black banding.

Though harmless, many species of hoverfly show 'Batesian' mimicry i.e. features such as yellow-and-black banding which mimic the colour/pattern of potentially harmful organisms such as wasps. This may help deter predators, especially if they have previously been stung by a wasp, though in humans it can cause unnecessary swatting by the entomologically uninitiated...

The common 'Marmalade Fly' Episyrphus balteatus feeding in a day-lily

A head-on view of E. balteatus. Note the eyes meet on the top of the head - this is often a clear indicator that the specimen is a male (and not just in this species); in females the eyes generally don't meet.

Myathropa florea showing the distinctive pale spots and bars on the otherwise dark thorax.

Scaeva pyrastri feeding on Buddleia davidii - note the white 'lunules' rather than yellow bands.

An oblique/side view of S. pyrastri showing the somewhat flattened abdomen.

Syritta pipiens showing the distinctively swollen and toothed hind femur.

 As well as wasp-like mimicry, a number of species mimic bees, including the 'drone-flies' of the genus Eristalis which mimic honey bees (Apis mellifera). 

Eristalis arbustorum (note the golden pubescence) on a dried-out dock (Rumex) plant.

The dark form of Eristalis tenax, one of the honey bee mimics in this genus. The paler form has paler, clearer banding. E. tenax may be found feeding alongside honey bees and can look very similar. The larval forms are very different though, with Eristalis producing the 'rat-tailed' maggots (named after their long posterior breathing tubes) which can be found in stagnant water.

Other species can be very different again. Many hoverflies are small and dark (such as Cheilosia), while some are bumblebee mimics such as Volucella bombylans and Eriozona syrphoides which is likely to be a fairly recent (1950s) colonist associated with spruce.

Merodon equestris, a mimic of hairy bee species with very variable colouration from almost all black to extensively brown and/or pale.

Rhingia campestris showing the long 'snout' in side view - a characteristic of this genus.

Of cours, it's not all about the flowers - hoverflies need to make sure there are plenty of their kind around next year. So, I shall leave you with a couple of pics of them doing exactly this. Feel the love!

A pair of Helophilus (probably H. pendulus).

A pair of Sphaerophoria scripta trying the back-to-back position. The female's on the right.

Reference

Stubbs, A.E. & Falk, S.J. (2002). British Hoverflies. BENHS, Reading.

Further reading (if you want to know about the larvae)

Rotheray, G.E. (1993). Colour Guide to Hoverfly Larvae (Diptera, Syrphidae). Derek Whiteley, Sheffield.