Sphaeroceridae

Lesser Dungflies

DIPTERA > BRACHYCERA | Higher Diptera

MUSCOMORPHA > SCHIZOPHORA > Sphaeroceroidea > Sphaeroceridae (145 species)

(subfamilies: Copromyzinae, Limosininae and Sphaerocerinae)

A pretty large family of small, typically stout, dark-coloured flies that are mainly associated with dung or decaying and decomposing plant matter. They may be found on fresh cow-pats often in the company of larger scathophagid dung flies or, subject to the species, on or in the vicinity of rotting organic matter, including supralittoral seaweed, carrion or on fungi.

Sphaerocerids are generally described as minute to small (1-5mm), usually dull, but sometimes shiny, dark brown to black flies with a few species that may have part of the head yellow or reddish-brown; the head is usually short and broad, higher than long; the eyes are always dichoptic; the thorax short and high; wings generally clear with the costa having a base, a subcostal break and, in some cases, a humeral break as well.

They can be visually distinguished from other small, dark acalyptrate species by their noticeably short and thickened hind basitarsus and, I believe, the presence of a very long arista. Good clear photos are essential for any level of identification, particularly a dorsal view showing the wing venation as that will help to confirm the subfamily, but for any chance of a genus or being able to actually determine the species, well-detailed side and front views will be required. I'm only able to put names to the individuals featured below as my photos had just about enough detail for the species to be identified by an expert from the Lesser Dung Fly Study Group.

The British list currently comprises 145 species in 39 genera and three subfamilies; previously 141 in 33 genera, but some subgenera have now been raised to generic rank. The smallest group are the Sphaerocerinae with just 11 species in 3 genera, then Copromyzinae with 18 species in 6 genera, and finally Limosininae, which is by far the largest subfamily with 116 species in 30 genera.

The larger and more frequently observed species in general are in the Copromyzinae, but there are a few others, such as Opacifrons coxata and Leptocera fontinalis (both in the Limosininae) that are regularly recorded. Looking at the distribution data as a whole, the family is well recorded although, when you look more closely at the numbers by county, it becomes very clear that quite a few regions, including both Dorset (VC9) and South Hampshire (VC11), are very poorly represented.

From what I can determine, there are quite a number of species that are both common and widespread, but there are also many that will only be found in certain areas or particular habitats. Unfortunately, I can find very little information regarding the species that I'm able to feature.

Copromyza equina and Copromyza nigrina are both predominantly coprophagous and, as such, are probably more likely to be found in open areas where there are cattle or horses. Although both of these species have been recorded from my garden, I should note that we back onto a small paddock that had a couple of horses in it when the photos were taken. Sadly, that's not the case now. A comment at the time, when I posted the photos of Copromyza equina to the UK Diptera group, confirmed that the extra setae on the scutellum are a good pointer towards the genus and that the dark band on the end of the rear femur is usually a good sign for equina along with the dusting of the anepisturnum (mesopleuron); less in Copromyza stercoraria and more in Copromyza nigrina. Whilst Copromyza nigina seems to be reasonably well recorded across most areas, Copromyza equina has very few confirmed sightings from the south - just two from South Hampshire and none from Dorset.

Crumomyia fimetaria is fungivorous and indeed the only photo I have of the species is on fungus. I cannot find any specific information regarding Crumomyia roserii, or the genus in general. There are seven Crumomyia species and the biology may not be the same. The two most frequently observed are Crumomyia nitida and Crumomyia fimetaria, although only the latter has been recorded locally and Crumomyia roserii has only been recorded once.

The Rachispoda genus includes 18 species and, according to the NBN Atlas database, the most frequently seen is Rachispoda lutosa, then Rachispoda cryptochaeta and Rachispoda limosa. Frustratingly, I can't find any general information about these species despite an extensive internet search. All I can say, is that when I saw the individual featured below that was in the company of a few tiny shoreflies that I assumed it was another ephydrid species and was surprised when it was pointed out that it was actually a sphaerocerid.