Trichoptera
Caddisflies
Insects in the order Trichoptera are commonly known as caddisflies or sedges. There are 199 species of caddisfly in the UK. Cased caddis larvae make elaborate cases out of silk, which they adorn with pieces of vegetation, stones or other material. Adult caddisflies are moth-like insects which generally fly at night. They hold their wings above their body in a roof-shape when at rest.
Conservation
The four nations of the UK each have a list of priority species. These species have been identified as being of principal importance, and there is a government commitment to support conservation measures for them. Trichoptera species that are identified on one or more of the lists are as follows: Glossosoma intermedium (Small Grey Sedge), Hagenella clathrata (Window Winged Sedge), Hydropsyche bulgaromanorum (Grey Flag), Ironoquia dubia (Scarce Brown Sedge), Apatania muliebris, Holocentropus dubius, Limnephilus coenosus, and Limnephilus elegans.
Life Cycle
As larvae, caddisflies live underwater. Caddisfly larvae can be divided into two groups: cased and caseless. Cased caddis larvae use a silk secretion to build a portable structure around themselves, made of materials such as sand, shells, stones and leaves. Some caseless caddis larvae also use silk, constructing a fixed shelter rather than a portable case, while others are free-swimming.
Caddis larvae moult four times as they grow. A fully-grown caseless larva builds a shelter, inside which it moults again and turns into a pupa. A cased caddis larvae does this within its portable case, after sealing it up. The adult forms inside the pupal skin and cuts its way out of the shelter or case. It swims to the surface or shore, and leaves behind the pupal skin as it emerges from the water. It flies away to mate, then, depending on species, the female enters the water to lay her eggs, or lays them nearby within a jelly-like substance.
Riverfly Monitoring
Volunteers taking part in the Riverfly Monitoring Initiative collect samples of freshwater invertebrates and record the numbers of individuals found within eight easily identifiable groups, including cased caddis larvae and caseless caddis larvae.
Monitors using the Extended Riverfly Scheme identify more groups within Trichoptera. The caseless caddisflies are divided into Green Sedge, Net Spinners and Non-Gilled, and identifiable cased caddisflies include Hood Case-Maker, Weighted Case-Maker, and Bush-Tailed Caddisfly.
There is also a Trichoptera Recording Scheme and Adult Caddisfly Occurrence Scheme, keeping records of caddisflies around the UK — see the Riverfly Recording Scheme page for more details.
Cased caddis (Potamophylax sp.) larva
Green sedge (Rhyacophila dorsalis) larva
Adult cased caddisfly
Trichoptera Guides
As well as the guides listed below, it is worth checking second hand bookshops and online outlets, as they can be a good source of identification books aimed at the hobbyist or angler.
An introduction to caddis and the identification of larvae with illustrations of various case constructions:
A Beginner's Guide to Caddis (Order Trichoptera) (PDF, 538KB) by Dr Ian Wallace, published by Bulletin of the Amateur Entomologists' Society Vol. 62 February 2003. This article has been made available by the Amateur Entomologists' Society.
Crofts S., 2019 Caddisfly Adults (Trichoptera) of Britain and Ireland. This guide has been written with the intent to introduce those with a strong interest but little experience in the identification of caddisflies. Perfect for those who wish to become familiarised with different caddisfly families prior to ventures in species-level identification, this book is a fitting accompaniment for caddisfly fieldwork. Included in this succinct book is a checklist of the caddisfly species within Britain and Ireland.
Wallace I., 2006 Simple key to caddis larvae. Field Studies Council. Development of this guide was supported by the Riverfly Partnership. An easy-to-use guide to Trichoptera families, with images and notes on each family.
Barnard P. & Ross E., 2008 Guide to adult caddisflies or sedge flies (Trichoptera). Field Studies Council. Development of this guide was supported by the Riverfly Partnership.
Edington J.M. & Hildrew A.G., 1995 A revised key to the caseless caddis larvae of the British Isles. pp.134, Freshwater Biological Association.
Wallace I.D., Wallace B. & Philipson G.N., 2003 (2023 reprint) Keys to the case-bearing caddis larvae of Britain and Ireland. pp.259, Freshwater Biological Association.
Trichoptera species
You can download the Trichoptera species list here.
Adicella filicornis
Adicella reducta
Agapetus delicatulus
Agapetus fuscipes
Agapetus ochripes
Agraylea multipunctata
Agraylea sexmaculata
Agrypnia crassicornis
Agrypnia obsoleta
Agrypnia pagetana
Agrypnia picta
Agrypnia varia
Allogamus auricollis
Allotrichia pallicornis
Anabolia nervosa
Apatania auricula
Apatania muliebris
Apatania nielseni
Apatania wallengreni
Athripsodes albifrons
Athripsodes albifrons var.interjectus
Athripsodes aterrimus
Athripsodes bilineatus
Athripsodes cinereus
Athripsodes commutatus
Beraea maurus
Beraea pullata
Beraeodes minutus
Brachycentrus subnubilus
Ceraclea albimacula
Ceraclea annulicornis
Ceraclea dissimilis
Ceraclea fulva
Ceraclea nigronervosa
Ceraclea senilis
Chaetopteryx villosa
Cheumatopsyche lepida
Chimarra marginata
Crunoecia irrorata
Cyrnus flavidus
Cyrnus insolutus
Cyrnus trimaculatus
Diplectrona felix
Drusus annulatus
Ecclisopteryx guttulata
Ecnomus tenellus
Enoicyla pusilla
Ernodes articularis
Erotesis baltica
Glossosoma boltoni
Glossosoma conformis
Glossosoma intermedium
Glyphotaelius pellucidus
Goera pilosa
Grammotaulius nigropunctatus
Grammotaulius nitidus
Hagenella clathrata
Halesus digitatus
Halesus radiatus
Holocentropus dubius
Holocentropus picicornis
Holocentropus stagnalis
Hydatophylax infumatus
Hydropsyche angustipennis
Hydropsyche bulgaromanorum
Hydropsyche contubernalis
Hydropsyche exocellata
Hydropsyche fulvipes
Hydropsyche instabilis
Hydropsyche pellucidula
Hydropsyche saxonica
Hydropsyche siltalai
Hydroptila angulata
Hydroptila cornuta
Hydroptila forcipata
Hydroptila lotensis
Hydroptila martini
Hydroptila occulta
Hydroptila pulchricornis
Hydroptila simulans
Hydroptila sparsa
Hydroptila sylvestris
Hydroptila tigurina
Hydroptila tineoides
Hydroptila valesiaca
Hydroptila vectis
Ironoquia dubia
Ithytrichia clavata
Ithytrichia lamellaris
Lasiocephala basalis
Lepidostoma hirtum
Leptocerus interruptus
Leptocerus lusitanicus
Leptocerus tineiformis
Limnephilus affinis
Limnephilus auricula
Limnephilus binotatus
Limnephilus bipunctatus
Limnephilus borealis
Limnephilus centralis
Limnephilus coenosus
Limnephilus decipiens
Limnephilus elegans
Limnephilus extricatus
Limnephilus flavicornis
Limnephilus fuscicornis
Limnephilus fuscinervis
Limnephilus griseus
Limnephilus hirsutus
Limnephilus ignavus
Limnephilus incisus
Limnephilus lunatus
Limnephilus luridus
Limnephilus marmoratus
Limnephilus nigriceps
Limnephilus pati
Limnephilus politus
Limnephilus rhombicus
Limnephilus sparsus
Limnephilus stigma
Limnephilus subcentralis
Limnephilus tauricus
Limnephilus vittatus
Lype phaeopa
Lype reducta
Melampophylax mucoreus
Mesophylax aspersus
Mesophylax impunctatus
Mesophylax impunctatus subsp.impunctatus
Mesophylax impunctatus subsp.zetlandicus
Metalype fragilis
Micropterna lateralis
Micropterna sequax
Molanna albicans
Molanna angustata
Mystacides azurea
Mystacides azurea var.albicornis
Mystacides longicornis
Mystacides nigra
Nemotaulius punctatolineatus
Neureclipsis bimaculata
Notidobia ciliaris
Odontocerum albicorne
Oecetis furva
Oecetis lacustris
Oecetis notata
Oecetis ochracea
Oecetis testacea
Oligotricha striata
Orthotrichia angustella
Orthotrichia costalis
Orthotrichia tragetti
Oxyethira distinctella
Oxyethira falcata
Oxyethira flavicornis
Oxyethira frici
Oxyethira mirabilis
Oxyethira sagittifera
Oxyethira simplex
Oxyethira tristella
Phacopteryx brevipennis
Philopotamus montanus
Phryganea bipunctata
Phryganea grandis
Plectrocnemia brevis
Plectrocnemia conspersa
Plectrocnemia geniculata
Polycentropus flavomaculatus
Polycentropus irroratus
Polycentropus kingi
Potamophylax cingulatus
Potamophylax latipennis
Potamophylax rotundipennis
Psychomyia pusilla
Rhadicoleptus alpestris
Rhyacophila dorsalis
Rhyacophila munda
Rhyacophila obliterata
Rhyacophila septentrionis
Sericostoma personatum
Setodes argentipunctellus
Setodes punctatus
Silo nigricornis
Silo pallipes
Stenophylax permistus
Stenophylax vibex
Synagapetus dubitans
Tinodes assimilis
Tinodes dives
Tinodes maclachlani
Tinodes maculicornis
Tinodes pallidulus
Tinodes rostocki
Tinodes unicolor
Tinodes waeneri
Triaenodes bicolor
Tricholeiochiton fagesii
Trichostegia minor
Wormaldia mediana
Wormaldia occipitalis
Wormaldia subnigra
Ylodes conspersus
Ylodes reuteri
Ylodes simulans
Images on this page — header photo: © ViniSouza128 / Adobe Stock; microscope photos: John Davy-Bowker; adult caddisfly photo: Stuart Crofts