The contents of the caddisfies "how to" guides section are the property of Dr Ian Wallace and cannot be reproduced without permission. If you wish to reproduce any part of the caddisflies "how to" guide section please contact the Freshwater Biological Association.
Introduction to caddisflies
Caddisflies are one of the groups of advanced insects that arose in the Permian (about 250 Million years ago) and were characterised PROBABLY by having hairy wings and a larva that used silk threads to re-inforce feeding galleries it made in the moss and algae.
This group, now extinct is called the Amphiesenoptera (translates as dressed-up wings).
Amphiesmenopteran evolution - One branch went mainly terrestrial, feeding on plants and by co-evolution with numerous plant species, evolved into well over 100,00 species - these are the Lepidoptera (Butterflies and Moths) The other branch went aquatic and remained generalist feeders with less chance of wide-ranging speciation so has only 12,000 species - these are the Trichoptera (Caddisflies).
Globally there are around 12,000 caddisfly species, 1,000 of these are European but only 198 species are found in Britain and/or Ireland.
Two main groups of caddis
One has a larva that makes a case that it carries around with it. This groups is called Integripalpia (named after the form of one of the adult mouthparts). They are usually called (true) cased caddis.
The other group has a larva that makes a fixed retreat, that also doubles as a food collecting apparatus. This group is called Annulipalpia or (true) caseless caddis.
The third group of caddis are the primitive families including Rhyacophila (a living fossil), Glossosomatidae (saddle case makers) and the Hydroptilidae (the micro caddis) that only make a case at the final instar. They are all distinctive and relatively easy to recognise.
Caddis cases
What are the cases forĪ
Camouflage - Caddisflies make theier cases from the surrounding material making them blend in to their environment.
Protection - Cases are difficult to eat i.e. too big to swallow or to suck in. Also a re-inforced tube of sand grains is difficult to chew.
Weight - A heavy case is difficult for the current to sweep away.
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| Cut-away case showing pumping action |
Also - The case is especially important for respiration. Living caddis larvae have silvery air-filled gills on their abdomen. Cased caddis pump oxygenated water through their cases and are therefore common in still and flowing water. Conversly, caseless caddis rely more on the current to bring oxygenated water. Therefore they are commonest in flowing water.
Caseless caddis shelters
The shelters and food-catching apparatuses of the caseless caddis are varied
