DIPTERA > BRACHYCERA | Higher Diptera

MUSCOMORPHA > SCHIZOPHORA > Calyptratae > Muscoidea > Muscidae (294 species)

(subfamily: Coenosiinae)

Coenosiinae (98 species)

This large subfamily of species which are often referred to as 'hunter flies' because of the predacious feeding habits of both the larvae and adults, is taxonomically separated into two tribes:

Coenosiini with eight genera: Coenosia (36), Limnospila (1), Lispocephala (10), Macrorchis (1), Orchisia (1), Pseudocoenosia (2), Schoenomyza (1), Spanochaeta (1)

Limnophorini with five genera: Limnophora (9), Lispe (10), Neolimnophora (2), Spilogona (23), Villeneuvia (1)

To date I've only knowingly photographed flies from four of these genera, which doesn't really surprise me given the likelihood of seeing many of these species and, more importantly, being able to recognise them to determine the genus or indeed identify the species. This is undoubtedly the reason why so many flies are under-recorded - for example, the second largest genus Spilogona with 23 species has but a single 25-year-old record from Dorset. Fortunately, there are quite a number of muscids that can be identified from photos with a bit of care, so I'm not going to worry too much about the genera I'm not able to represent.

Coenosia

A large genus of small, rather non-descript predatory flies that are generally difficult to identify from photos. That said, I was surprised to see that quite a few Coenosia species have been recorded locally. The most frequently observed is Coenosia tigrina, a specialist predator of small flying insects that is often referred to as the 'type species' or the Common Tiger Fly. Although it's the only member of the genus that I'm able to feature, I'm sure I will have seen other species that I've either passed by or have photographed, but have not been able to identify.

Searching the NBN Atlas can often produce unexpected results and that was certainly the case here when I found that no less than six Coenosia species featured in the top twenty muscids recorded in Dorset (VC9), which I'm sure would have been made by someone who specialises in these species rather than a casual observer like myself. Nevertheless, it's worth noting that the other five were Coenosia femoralis, C.pumila, C.mollicula, C.vibrissata and C.distinguens.

A further observation here is that Steven Falk's Flickr album for this particular genus is still under construction, which is a great shame as it's the most useful and, in fact, virtually the only readily available resource for information. There are photos of a few species, but no descriptions, so unfortunately, it's of little use at the moment.

Schoenomyza    

Consisting of a single rather small, 2.5-3.5mm, brownish species Schoenomyza litorella that has a distinctively marked abdomen with shiny black bands around the base of the tergites, and a noticeably broad head and frons with a pale greyish-white forehead and face in the females, and shining golden-yellow face in the males. As well as being found in damp woodland and grassland areas this species can also be particularly abundant in waterside locations. 

Limnophora

These flies are mainly associated with flowing water, especially clean streams, where the larvae are predators of other larvae, including mosquitoes and blackfly. The general deterioration of water quality has had an effect on many species over the past fifty or so years and, from a quick look at available records on the NBN Atlas, it appears that Limnophora triangula, Limnophora maculosa and Limnophora tigrina are now the most frequently observed. Species such as Limnophora riparia that used to be relatively common are now rarely recorded. Obviously, the status of individual species varies from area to area. Local records for Dorset (VC9) and South Hampshire (VC11) are poor and, consequently, not representative of the true situation.

The first individual featured below was identified as Limnophora tigrina by an expert on the UK Diptera FB group. It was on the banks of a small tributary of the River Test, which is one of the cleanest chalk streams in the country. The second, Limnophora triangula, was found in damp woodland on a spit of land between two lakes, which is not typical habitat for the species. However, the location is close to the River Stour and a couple of streams that run through this large wetland area.

Lispe

Small, predatory, semi-aquatic flies that are characterised by having a broad frons in both sexes, enlarged spoon-like palps and a hairy anepimeron. Widespread, but very much under-recorded. Ten species are recognised, but three have no current records. The most frequently observed is Lispe tentaculata which, although occurring in a variety of both inland and coastal habitats, is probably the most likely species to be found on the mud banks along, or around, the margins of flowing or standing freshwater. Similarly, with Lispe pygmaea and, although there are very few confirmed records, Lispe uliginosa.

Lispe tentaculata - identified as much from the general appearance and habitat than from any specific features, but greyish with dark markings on the abdomen and feint stripes on the thorax; hind femur with 2-5 long ventral bristles; males with the basal half of the hind metatarsus slightly, though distinctly swollen.

In coastal locations, Lispe litorea is the most likely species along shorelines, whereas Lispe caesia, Lispe loewi and Lispe nana can be found in saltmarsh. I've found two different saltmarsh species whilst photographing ephydrid shore flies but, with limited information, the following identities are rather tentative. 

Lispe caesia - body dusted silver grey with brown paired spots on tergite 3; palpi densely dusted glistening white.

Lispe nana - brownish grey with a pair of dark presutural marks on the thorax and extensive abdominal markings with no clear pattern, but often appearing as stripes; jowl below eye hardly 1.5 times as deep as the width of the third antennal segment.

Crazy as it may seem, it doesn't look as though any of the saltmarsh species have ever been officially recorded from either Dorset (VC9) or South Hampshire (VC11), despite having suitable habitat at various sites from Lodmoor in Weymouth, locations around both Poole and Christchurch Harbours and an extensive area from Keyhaven to Lymington and beyond.

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