Playing Top Trumps for Water Quality Month | Digital Collections Programme

We are currently digitising 75,000 freshwater insects belonging to three small orders. The presence of these groups can give us an idea about the water quality of the river they live in. As August is #WaterQualityMonth we thought this would be a great time shed some light on these orders of insects that you might not have heard much about before.

The group we are digitising are known as EPT for short, which is made up of the three orders Ephemeroptera (mayflies), Plecoptera (stoneflies) and Trichoptera (caddisflies) – or EPT for short. You can find out more about this project by reading our previous blog.

Ephemeroptera (mayflies), Plecoptera (stoneflies) and Trichoptera (caddisflies)

There are approximately 22,000 species within these three groups, though scientists continue to find and describe new species each year. While some other insects are tolerant to higher levels of pollutants in freshwater, certain mayflies, stoneflies and caddisflies are very sensitive to these contaminants, making them the perfect early warning system for river pollution.


The Museum’s collection contains pinned specimens, slide mounted material and specimens in vials of spirit. The current project will digitise approximately 65,000 pinned insects, 9,000 slides and 2,345 vials. If you wish to see the card in better detail please take a look at this PDF.

Ephemeroptera (Mayflies)

While their larvae live underwater hidden from view, adult mayflies live for a short time with one species (Dolania americana) livingfor around 5 minutes before mating, laying eggs and dying. Cloeon dipterum is one of approximately 3,800 species of mayfly. It is known by the common name ‘pond olive’ and is present in most UK ponds. As this species is present in most ponds no matter what pollution level, we have given it a low water quality score of 2, but within the group there are species which are very sensitive to water quality. All insects moult their exoskeleton as they grow, but we think Mayflies have a pretty good party trick – the nymphs and have been known to go through as many as 45 moults or outfit changes if you will, and they are also they only insects which moult as adults. Cloeon dipterum

Plecoptera (stoneflies)

Perla bipuncta is a species of stonefly (Plecoptera) that we think has a great party trick and water quality score. They are engulfer predators, meaning that they eat their prey whole, alive and in one mouthful! They also eat the other two orders. Their larvae are very particular, liking cool well-oxygenated running water and are sensitive to nutrient pollution. So, if you discover this species thriving in an area it would indicate very high water quality. Perla bipunctata pdf 

Trichoptera (caddisflies)

                Rhyacophilia vao       Agapetus fuscipes

Caddisflies normally have a very good party trick as caddisfly larvae build cases for their bodies. These can be made out of stones, pebbles, leaves, shells and some species larvae have even been employed as jewellery makers – the larvae are provided with gemstones and precious metal fragments which they incorporate into their cases. However, the species Rhyacophilia vao is one of the few caddisflies that does not build a case, so we have marked their party tricks down accordingly. Rhyacophilia vao are predetory hunters, so we have marked them up for feeing habits, and they are moderately intollerant to pollution so we have given them quite a high water quality score.

Agapetus fuscipes is another species of caddisfly that not only builds cases but builds cases that look like the shell of a tortoise. The larvae are extremely intolerant to pollution so their presence in a stream would indicate very high water quality.

And the Top Trump goes to…

In the Digital Collections Programme we often talk about digitisation as a way to unlock the collection. Exploring the collection in new and creative ways enables us to shine a light on specimens that might not be so well known and shed some light on how our collections will be used to further scientific understanding. Not only will this new resource of important bioindicators be shared openly for the world’s scientists to use, but the data from the EPT collection will be used by the International Union for Conservation of Nature, which assess how at-risk species are for extinction.

We would love to know who you think should win our game of top trumps and if you liked this different way of exploring our work? What would you like to hear about from us next? Let us know and keep up to date with our latest news by following us on Twitter and Instagram.