DIPTERA > BRACHYCERA | Higher Diptera

EREMONEURA > Empidoidea > Dolichopodidae (308 species)

(subfamilies: Achalcinae, Diaphorinae, Dolichopodinae, Hydrophorinae, Medeterinae, Neurigoninae, Rhaphiinae, Sciapodinae and Sympycinae)

A large family of small, mostly brightly coloured, long-legged, rather active flies that are scavengers and predators of soft-bodied prey such as aphids or springtails.

Family characteristics are given as tiny to medium (1-9mm) flies with long slender legs; body slender, but stouter in smaller species; body colour usually greenish metallic lustrous, although in some cases dull yellow, brown or black; eyes virtually always dichoptic; third antennal segment largest with a usually long, apical or dorsal arista; mouthparts usually short and with a wide aperture adapted for sucking small prey; wings clear or tinged, in some cases partially strongly coloured, marked or with distinct spots; first basal wing cell very short, anterior cross-vein well within basal quarter; posterior cross-vein prominent; legs, the tibia in particular, usually with long bristles.

Unfortunately, Dolichopodidae is one of a number of fly families that is rather poorly supported in respect of general information, which is why I haven't attempted to describe any of the individually named species that I'm able to feature. And, not surprisingly, with just over 300 species they are generally very difficult, if not impossible, to distinguish from photos, which is why many cannot be taken past the genus, or even to the genus with certainty. Although understandable, it's a pity, because they are attractive little flies that can be seen and photographed in a range of habitats, which can often result in some very pleasing images.

Despite the problems with identification that photographers will face, the family as a whole are well recorded, so I guess there must be a fair number of dipterists around the country who specialise in them. They have their own 'recording scheme' that also covers the closely related empids, but that doesn't provide much information. Steven Falk has a Dolichopodidae album on his Flickr site with, at the time of writing, photos of 27 species, but sadly with no descriptions. There are also quite a few photos on the NatureSpot website. Mike Hackston has a comprehensive 'key' but, for that to be of any use, you first need to establish whether the individual in question is male or female and then make an attempt at determining the genus. The wing venation and colour of the antennae may help, but most of the important diagnostic characters are associated with various bristles on the thorax, scutellum and/or legs. I haven't had much success, which is why I have to rely on the UK Diptera FB group where, with a bit of luck, I might get an identity confirmed or at least a comment that the species can't be determined. Obviously, it's unrealistic to hope for a response to every post, so I now assume that 'no comment' means 'unidentifiable'.

Although Dolichopus ungulatus is the most frequently recorded species nationally, locally it's Chrysotus gramineus followed by Tachytrechus consobrinus, which is interesting because although Chrysotus gramineus is in second place nationwide, Tachytrechus consobrinus is way down the list in around sixtieth place. There are a number of other Dolichopus species that are regularly recorded so hopefully I can add a few of those at some point, but at the moment the only other member of the genus that I've had identified is Dolichopus griseipennis and, even then, was qualified as 'very likely' rather than certain. Better luck though with the particularly attractive Poecilobothrus nobilitatatus that can often be identified from photos with reasonable confidence, particularly the males with their conspicuous white wing tips.

Neurigona quadrifasciata has very few confirmed records, but there are some from Dorset, so I was pleased to get that one positively identified. Similarly, with Sciapus platypterus, although with the individual in question being a male it was a bit more straightforward as they have distinctive white middle tarsi.

Although it's not the rarest species in this large genus, Medetera diadema is seldom recorded so a degree of caution is required. It looks right and strongly competes with the more common species Medetera saxatilis and Medetera truncorum for its frequency of being seen on walls.

The widespread and common, rather small Campsicnemus scambus can be identified by its modified front and middle legs, particularly the distinctive dilated and curved middle tarsi. I wish I could be as sure about the final species Hydrophorus oceanus but, unfortunately, I can't. The mating pair photographed on Keyhaven Lagoon are considered 'very likely', but there's always a chance that the others could be a different species!

I previously touched on the fact that photographing these flies can be very rewarding as they can provide some quite interesting images. The problem is, that if they can't be identified, the photos are filed away  and usually forgotten so, I thought it would be nice to feature a few of my favourites, which is why my coverage of this family now extends to the next page.

Please use the forward 'next page' (>) button above to view some of the unidentified individuals I've photographed.

Updated Nov.24 (v.3)