DIPTERA > NEMATOCERA | Lower Diptera

PSYCHODOMORPHA > Scatopsoidea > Scatopsidae (46 species)

(subfamilies: Aspistinae, Psectrosciarinae and Scatopsinae)

It's useful to note that scatopsids were formerly classified within the BIBIONOMORPHA infraorder, where they were regarded as a subgroup of the Bibionidae on the basis that both families superficially resemble each other in being stout black flies with short antennae and not dissimilar wing venation. The problem has always been that the general appearance of bibionids and scatopsids is not particularly typical of the Nematocera so, despite various morphological differences, they remained closely linked for a long while. In fact, in many current classification systems they're still in the BIBIONOMORPHA, but distinctly as a separate family, whereas the British List places them within the PSYCHODOMORPHA alongside species such as the Anispodidae wood gnats, which are featured on the previous page. There is however, some disagreement about the structure of this group and whether certain families have been correctly assigned but, for now at least, that's where they've been taxonomically positioned, albeit partially separated in their own superfamily Scatopsoidea.

The next point of interest, possibly as a result of their history, is that the family does not have a universally recognised common name. In Britain we tend to use the term 'dung midges' whereas in some other countries, such as the US, they're called 'minute black fungus gnats'. Neither name is right or wrong and indeed either could be used, but the difference between the two does raise questions, which is probably why many publications and listings, including the current British Diptera Checklist, don't use common names. My first thought was simply in respect of whether they should be defined as midges as I was under the impression that, with exception of the Cecidomyiidae gall midges, all the other 'midge' families are grouped together in the CULICOMORPHA together with mosquitoes. I spent a bit of time trying to see if there was a recognised way of determining whether a species should be referred to as 'midge' or a 'gnat'. There wasn't, although I did come across various comparisons, such as midges thrive near water sources whereas gnats live in moist organic environments, or statements regarding whether the species bite or not, which was contradictory and didn't make much sense. There was also an article that made particular reference to their appearance stating that "gnats are more delicate, with long legs and wings" and that "midges tend to have shorter legs and a more compact body". I thought that was strange and assumed it was an American reference, but it was from an author based in London referring to British species! I came to the conclusion that, to some extent, the use of 'midge' or 'gnat' to describe certain small flies is a matter of choice unless you're specifically referring to an accepted common name; for example, with the chironomid non-biting midges or the various fungus gnat species.  

Moving on, we then have one name that implies they're mainly associated with 'dung' and the other with 'fungus'. Again, neither is right or wrong, as scatopsid larvae can be found in all kinds of rotting organic matter, but the specific reference could be misleading. In the end I decided to stick with the name 'dung midges' especially as the only species I've photographed was neither minute or black, as noted below.

In general terms, the adult members of the family can be described as minute to small, 0.5-4mm long, mostly black or dark brown, mostly shining flies, although a few with some yellow; typically, stout and compact, although sometimes with a more elongated body; antennae relatively short with 5-10 flagellomeres; wing venation is characteristic with only the costa and the radial sector sclerotised forming a prominent closed cell along the front edge.

There are three subfamilies; Aspistinae with five species in two genera, Psectrosciarinae with six species in a single genus, and Scatopsinae comprising thirty-five species in fifteen genera and four tribes. Detailed keys are available that assist in identifying the subfamily, tribe, genus and species, but I think that unless the individual in question is distinctive and can be visually distinguished, you're not likely to get very far from photos. I'm not sure how I came up with the identification of the specimen featured below. I thought it was with assistance from an expert on the UK Diptera FB group, but I'm not able to verify that.

It's hard to find general information on any of these species, but if you keep searching the internet you can sometimes hunt out a hidden article or a snippet or two of detail, especially with species that also occur in Europe as that obviously widens the scope. There are actually quite a few really informative European insect websites that are well worth looking at and, with the ability now of obtaining an instant translation, so much more useful than they were a few years back. Anyway, that's what happened here while searching for information on Apiloscatopse flavicollis when, on the verge of giving up, I stumbled across a 'species account' on a Polish website, which included a couple of nice photos that looked very much like the individual I photographed. Here the author had confirmed that the females were little more than 2mm long, whereas males averaged 3-4mm (I assume he was referring to body length rather than wing length); their colour was distinctive as other species in the genus (in Poland) were darker; they were not easily found, but in the right place and at certain times could be numerous; occurring mostly in forests or parkland habitat; adults active from June through to early October; often found feeding on pollen; the larvae develop in rotting leaf litter and compost.

New family, added Dec.24 (v.1)