DIPTERA > BRACHYCERA | Higher Diptera

MUSCOMORPHA > SCHIZOPHORA > Acalypratae > Sphaeroceroidea > Heleomzidae (56)

(subfamilies: Heleomyzinae, Heteromyzinae and Suilliinae)

Heleomyzidae, previously known as the Helomyzidae, and for a while as Heteromyzidae when it was proposed that the family should be directly grouped with the Sphaeroceridae, now includes 56 species in three subfamilies. There were a few more species, but they have now been separated and placed into four closely related families, Borboropsidae, Cneospthidae and Chiropteromzidae each with a single species, and Trixoscelididae, with five species.

The recently established Helomyzid Recording Scheme includes both Heleomyzidae and Trixoscelididae.

They are a diverse group of species where the larvae are mostly associated with decaying vegetation, fungi, carrion or dung, very similar to the Sphaeroceridae. Some species are also known to occur in bird's nest and mammal burrows.

Family characteristics are given as minute to large (1.5-12mm), robust, pallid yellow to dark grey or brown or, in some cases, reddish flies; arista bare or plumose; ocelli present; ocellar bristles present; postvertical bristles converging; one or two pairs of frontal bristles, curving outward or backward; interfrontal bristles absent; interfrontal setulae present or absent; vibrissae present; wings clear, tinged or with a pattern, especially along the crossveins; costa with subcostal break; vein Sc complete; crossvein BM-Cu present; cell cup closed; tibiae usually with dorsal preapical bristle.

The most useful feature though for ascertaining that the individual in question is a heleomyzid fly is the regularly spaced spines, or costal bristles, along the fore edge of the wings. Identification beyond there to genus and hopefully species is far more involved, particularly when you're just relying on photos.  As usual, good dorsal, lateral and, if possible, frontal shots are needed. The identity of all the individuals featured below were kindly confirmed by Ian Andrews who set up the scheme. Currently, all but one, are in the Suillia genus, which includes many of the most frequently recorded species. I was previously relying on a modified version of the original 'key', but with very little success as I was never sure if I was interpreting features correctly, which is difficult if not impossible from photos. With experience you can look at a photo and get a good idea of the species before checking, but I'm certainly not at that stage and probably never will be. I've always struggled to confidently interpret written keys and, although I haven't been photographing flies for that long, have wondered why, when there are now so many good quality photos to refer to, that some of these keys haven't been updated. I was, therefore, very pleased to see that Ian Andrews has done just that with the Suillia key, which now includes numerous photos of all the important features. The Recording Scheme home page has also been updated and now provides links to other equally useful material, but the Suillia key is almost certainly the one that I will use the most.

I'd previously accumulated very few notes regarding the handful of species I'd photographed, but am now in a position to include a bit more information courtesy of the new key.

Suillia affinis - a distinctive, relatively large (6-7.5mm wing length) species that has a full covering of setae on the scutellum, heavily marked wings, fore and hind tibia darkened apically, deep genae and long plumose arista; common and widespread, most frequent in woodland and can be seen pretty much throughout the year.

Suillia atricornis - a medium-sized (5-6mm wing length) Suillia that has a shiny thoracic dorsum and clear wings, and the only member of the genus with black antennae and a humeral bristle; a woodland species that is most frequently found around fungi.

Suillia bicolor - much the same size as the previous species, but with a darker thoracic dorsum, a rounded scutellum that is sparsely covered with very short setae on the edges and the disc, although hard to see; the wings are clear and the costal spines are typically shorter than seen in the other species; the males have a small hook ventrally at the distal end of the fore basitarsus; again common in woodland, particularly in the vicinity of fungi.

Suillia variegata - the most frequently recorded helomyzid; a slightly smaller species (5-5.5mm wing length) with a narrow gena and long arista in comparison with Suillia affinis, but easy to distinguish purely by the well-marked wings that have a subapical band with whitish blotches around the wing tip; surprisingly, I've only photographed the one individual featured below, despite being common in various habitats including woodland and gardens.

Tephrochlamys rufiventris - I can't find any information about this species or, more importantly, its distinguishing features as I don't have access to a full 'key'. However, the individual featured below was officially identified and is still, currently, the most recent accepted Dorset record for the species. As a point of reference, the unidentified, dark- coloured species in the previous photo did attract the comment that, despite the fact that it couldn't be identified, it does have strong presutural dorsocentral bristles, which rules out Tephrochlamys, so one can only presume that the absence of such bristles is an indicator of the genus.

Updated Nov.24 (v.2)