Cataloguing caddisflies

Figure 1: A reminder of my fume cupboard workstation!

So in continuing my work with the Alan Brindle aquatic insects collection I’m well underway with cataloguing the caddisflies (Order: Tirchoptera).

One of the reasons why there are so many aquatic insects collected by Alan Brindle from rivers in the north west is that from 1972, he started a complex entomological survey, mainly of Diptera but also of the smaller aquatic orders, over the north-west, on the 10-kilometre recording system (Reports 1972 – 73). This survey resulted in additions of thousands of specimens (both adults and larvae) which were identified and incorporated into the general collection (Reports 1972 – 80) (Logunov 2009/2010).  This collecting only ceased with Alan’s retirement in 1982.  He placed particular emphasis on the immature stages of Trichoptera, because their identification presented problems, and already by 1976, over half the British species were represented in the Museum’s larval collection (Report 1975 – 76) (Logunov 2009/2010).  This is the collection that I’m currently cataloguing now.

Figure 2: Despite focusing on larvae, Brindle also collected and identified adult (imago) forms like this Phryganea varia.

The name ‘Trichoptera’ comes from the Greek meaning hairy wing, as the adults have hairy wings.  They are closely aligned with the Lepidoptera (butterflies and moths) order of insects, and are sometimes placed in the superorder Amphiesmenoptera.  Like butterflies, they are holometabolous, meaning they undergo complete metamorphosis with a pupal stage which usually lasts for a few weeks.  Like other orders of aquatic insects, most adults are non-feeders and focused on mating.

Some caddisflies are filter-feeders, some eat vegetation, and some are even predators!  Caddisflies are unusual in that the larvae make themselves protective cases of silk decorated with whatever substrate happens to be available.  So this could include stone, vegetation, sand, or twigs; examples of which are shown below:

Figure 3: Odontocerum albicorne larvae uses small stones (with a capstone to protect the rear end)…

Figure 4: Phryganea varia uses a patchwork of vegetation…

Figure 5: Sericostoma personatum uses sand (and a capstone)…

Figure 6: Finally, larvae of the genus Silo use small, blocky stones.

Together with stoneflies and mayflies which I’ve previously been working on, caddisflies feature importantly in bioassessment surveys of streams and other water bodies as their species-richness can indicate river quality. This is why the work I’m doing in cataloguing them is very important.  It will enable us to compare previous species assemblages with those found today in order to see if there have been any changes in water quality.  Just one way which museums can play a vital role in aiding the work of scientists and other researchers today.

References

Logunov, D. (2009/2010) British Entomology collections of the Manchester Museum Journal of the Lancashire & Cheshire Entomological Society 133-134.

Wikipedia, (2011) Caddisfly (online) available at http://en.wikipedia.org/wiki/Caddisfly [accessed 06.09.12].

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About Trainee Curator

I will be writing a blog about the next twelve months spent as a trainee biological curator based at Manchester Museum.
This entry was posted in Trainee's diary and tagged , , , , , , . Bookmark the permalink.

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