DIPTERA > BRACHYCERA | Higher Diptera

MUSCOMORPHA > SCHIZOPHORA > Calyptratae > Muscoidea > Fanniidae (61 species)

(subfamilies: none)

The fanniids used to be grouped with the muscids, but are now separated into their own family.  

There are just two genera, Fannia and Piezura, with all but two species being in the Fannia genus. The majority are small to medium-sized (2-5mm body length), although some larger up to 9mm, mainly dark-coloured flies that, in most cases, are unidentifiable from photos.   

Although identification to species is difficult, there are a couple of features that help to distinguish fanniids from muscids. The most useful, as long as long as it is visible, is that unlike Muscidae where the primary anal vein A1 is usually well-developed and separated from the axillary vein A2, in Fanniidae it's distinctly weaker, but with A2 having a distinct curve which, if extended, would intersect with A1. In both cases neither anal vein actually reaches the wing margin. Further features are, that in males, the middle tibia has an erect pubescence beneath and, in females, interfrontal bristles are absent and frontal orbits broad. There's also a specific dorsal bristle on the hind tibia, which is probably more useful during close examination rather than a detail that's going to be obvious in photos.

Notwithstanding those species that have adapted to human environments, notably Fannia canicularis and Fannia scalaris, respectively known as the Lesser Housefly and Latrine Fly, adult fanniids occur mainly in or near woodland areas, rather than around open habitats. In warm, sunny weather, the males may be seen in characteristic dancing swarms or just slowly flying beneath the overhanging foliage, whilst the females tend to stay hidden in low vegetation.

Fannia lustrator is one of the more frequently recorded species even though the identity from photos is usually given as 'likely' rather than certain. It's one of the larger fanniids, typically averaging around 7-9mm, with a grey thorax and somewhat variable orangey-brown to reddish coloured abdomen. The base of the wings are yellowish-orange, the mid and hind legs generally reddish and the front legs darker. It has a certain 'look' about it that some experts can recognise.

Updated Nov.24 (v.2)