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University of Copenhagen
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Butterflies on needles to be digitised at UCPH museum

Digitisation — There are two million butterflies in the old scientific collections at the Natural History Museum of Denmark. Now they are to put in a database, and this will reveal patterns in nature over the last 250 years.

Butterflies are sensitive to small changes in their environmental conditions. In this way they work as sensitive barometers, revealing the true state of nature.

This is why science is so interested in butterflies, and the Natural History Museum of Denmark (SNM) and the University of Copenhagen (UCPH) has a collection of two million of them from the last 250 years.

Throughout this time, butterfly collectors have written a small label on each captured butterfly specimen. It worked well at first, when the collection was not big. But now researchers at SNM hope that the digitisation of the collection can tell us more about the changes in our climate and environment.

If digitised – a gold mine of information

The labels have to at least indicate the time and place where the butterfly has been captured, but the butterflies in the collection can reveal much more if you can analyse and comprehend all the information at the same time.

“Have the different species changed their shapes over time? Have they grown larger or smaller? Do their colour patterns change? Has the difference between males and females become greater or smaller over time? Have they changed colour – as in general when the climate gets warmer there is a tendency for butterflies to go brighter. There is a real potential in this if we can get the information from the labels into a database,” says Thomas Pape, entomologist and curator at SNM.

The Natural History Museum of Denmark has in its possession a veritable gold mine of information that can tell us more about our nature and our climate through 250 years. But this gold mine cannot be exploited before the collection is digitised. To solve this problem, Thomas Pape and his colleague Anders Drud Jordan who is the head of digital production at SNM, have set up the Danish Butterflies and Moths 2020 Challenge and put it out on a website.

Citizen science and crowdsourcing on butterflies

The idea is that people who are not researchers themselves can sit at home in their living room, read the photographed labels from the butterfly collection, and log this information into a database which has been set up for the purpose. This is called crowdsourcing – sharing tasks via the internet to those that are interested – and it is necessary as there are too few researchers to be able to do the registration alone.

Discover the digitisation process yourself:

At the Geological Museum, which is part of SNM, there is currently an exhibition about the butterflies that gives an insight into the museum’s extensive collection of butterflies and their significance for us.

In the exhibition guests are invited into a room where they can see the digital processing of the museum’s butterflies.

Link to the Butterflies exhibition. Nature’s quiet messengers


Thomas Pape says that crowdsourcing is a method that is gaining ground in many areas, and that it is often a part of what is called citizen science. It gets anyone who is interested to be involved, but checking the information may be needed, as people can get to write mistakes – even the scientists who have a lot more experience in interpreting old labels.

“The website therefore contains a quality control, which means that several users have to write the labels from the butterflies in before they disappear from the website. In addition, we have asked colleagues from around the world, what their experience has been in requiring a two, three or four time match to be able to log a single individual before the database accepts it,” he says.

Impossible in practice to get all two million into the database

So far, the SNM has started up a pilot project where they have put the photos of 4,000 butterflies and their labels into a portal for crowdsourcing projects. So there is a long way to go to reach the two million specimens in the collection. But it is not necessary that all of them get logged into the database, admits Thomas Pape.

“We have been a bit naughty when we on previous occasions have written that we want all two million butterflies to be logged. Of course, we would like it, but this would be too time-consuming,” he says and continues:

Digitisation in practice

Crowdsourcing-projektet kræver, at hver eneste somemrfugl fotograferes sammen med sin etiket samt en farve- og størrelsesskalaThe crowdsourcing project requires that every butterfly is photographed with its label, and a colour scale and size scale.


“Keep in mind that each and every specimen in the collection has to be handled in a way that the label first has to be taken off for the photo, and if the project is to make sense, then we also have to attach a new label with a QR code on the butterfly. Then you could ask: How many seconds does this take for a butterfly? When you multiply the number of seconds with two million, you realise just how gigantic this task is,” says Thomas Pape.

The project has been assisted by the Department of Computer Science, which is developing new and faster ways to be able to digitize the many butterflies, in order to save time.

Thomas Pape sees SNM at one point applying for money to get half of the Danish butterflies digitised in the collection.

“This is a bit more manageable, and as a national, natural history museum, it makes sense to give priority to the Danish individuals first,” says Thomas Pape.