Insect life on the Teifi

During 1995 and 1996, Melvin Grey and Pat O'Reilly carried out a survey of the water life of the River Teifi as part of the research for a new book, Matching the Hatch, published in 1997. The results are surprising: they were able to identify several species not generally thought to occur this far west. In fact, the fly life of the Teifi is considerably more varied than that which they found in the rich chalk streams of southern England. Members who fish for trout may find useful this summary of their findings.

Upwinged flies - Ephemeroptera
Common name	Scientific genera and species	Peak time	Abundance
Mayfly	Ephemera danica	Spring	moderate
Olive upright	Rithrogena semicolorata	Spring	high
March brown	Rithrogena germanica	Spring	moderate
Autumn dun	Ecdyonurus dispar	Autumn	moderate
Large brook dun	Ecdyonurus torrentis	Spring	moderate
Large green dun	Ecdyonurus insignis	Summer	low
Yellow may	Heptagenia sulphurea	Spring	high
Dusky yellowstreak	Heptagenia lateralis	Summer	moderate
Purple dun	Paraleptophlebia cincta	Summer	low
Turkey brown	Paraleptophlebia submarginata	Spring	very low
Blue-winged olive	Ephemerella ignita	Summer	high
Large dark olive	Baetis rhodani	Spring	moderate
Medium olive	Baetis vernus; Baetis tenax	Summer	high
Small dark olive	Baetis scambus	Summer	high
Iron blue	Baetis muticus	Summer	high
Pale watery	Baetis fuscatus	Summer	high
Pale evening dun	Procloeon bifidum	Summer	moderate
Small spurwing	Centroptilum luteolum	Summer	high
Large spurwing	Centroptilum pennulatum	Summer	moderate
Caenis fly	Caenis and Brachycercus species	Summer	high
Two rather surprising omissions are the late march brown, Ecdyonurus venosus, which is generally common on spate rivers, and the sepia dun, Leptophlebia marginata, which is found in some North Wales rivers. It would be good to hear from any members who have positively identified these species. The yellow evening dun, Ephemerella notata, doesn't feature in the list; anyone seen this fly on the Teifi?
Sedge flies - Trichoptera
Only a small selection of the sedges, stoneflies, midges and other flies was included in the survey, but again the findings may prove useful to trout fishers on the Teifi.
Common name	Scientific genera and species	Peak time	Abundance
Grannom	Brachycentrus subnubilus	Spring	high
Brown sedge	Anabolia nervosa	Autumn	moderate
Brown silverhorn sedge	Athripsodes albifrons	Summer	high
Caperer	Halesus radiatus	Autumn	moderate
Sand fly	Rhyacophila dorsalis	Summer	moderate
Cinnamon sedge	Limnephilus lunatus	Spring	moderate
Large cinnamon sedge	Potamophylax latipennis	Summer	high
Grouse wing	Mystacides longicornis	Summer	moderate
Welshman's button	Sericostoma personatum	Summer	high
Marbled sedge	Hydropsyche instabilis	Summer	low
Black sedge	Silo nigricornis	Summer	high
Yellow spotted sedge	Philopotamus montanus	Spring	moderate
Black silverhorn	Mystacides nigra	Summer	high
Stoneflies - Plecoptera
Common name	Scientific genera and species	Peak time	Abundance
February red	Brachyptera risi	Spring	low
Large stonefly	Perlodes microcephala	Spring	moderate
Small yellow sally	Chloroperla torrentium	Summer	high
Yellow sally	Isoperla grammatica	Summer	high
Needle fly	Leuctra fusca	Autumn	high
Small brown	Nemoura cinerea	Summer	low
True flies - Diptera
Common name	Scientific genera and species	Peak time	Abundance
Black gnat	Bibio johannis	Spring	moderate
Hawthorn fly	Bibio marci	Spring	high
Medium craneflies	Tipulidae	Summer	high
Daddy-long-legs	Tipula maxima	Autumn	high
Reed smuts	Simulium species	Summer	moderate
Large green midge	Chironomus plumosus	Summer	high
The heather fly was a conspicuous absentee during the survey, but it is sometimes seen by the Teifi.

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Insect life on the River Teifi

Upwinged flies - Ephemeroptera

Sedge flies - Trichoptera

Stoneflies - Plecoptera

True flies - Diptera