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Exploding the myth

Posted by Blaps Mar 29, 2011

As entomologists it is not only taxonomy that we are concerned with; we collect and study beetles in order to give a name to a species, so that conservationists, ecologists, even policy makers, can make decisions that hopefully will benefit the environment and the little creatures that live within and depend upon it.

However, we practice a different kind of insect conservation here in the Museum, a very specific specimen level conservation which ensures that the specimens we care for (and many of these are over 200 years old) remain readily available to science, to inform the very things mentioned above.


This week let’s look at verdigris. Not the kind of lovely blue-green patina found on Greek statues or the copper paint used to illuminate ancient manuscripts, rather the copper alloy of some entomological pins, which when exposed to the fats and lipids found in an insects’ body (as well as the gases found within an insect drawer), react to cause a ‘filamentous explosion’ of the alloy, and can ultimately destroy the body of an insect.


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Some Cerambycidae affected by verdigris - note the specimen in the centre whose wing is becoming disslocated from the body


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Here is what you don't want to happen - ever! Fifteen years of verdigris growth (specimens retained for demonstration purposes, courtesy of Malcolm Kerley)



So what is verdigris? The name verdigris originates from the Old French word verte-grez, an alteration of vert-de-Grèce (green of Greece), since it was used by Greek artists as a pigment for painting and other artistic crafting.


Here is the chemistry bit:

Verdigris is a green pigment which forms when copper, brass (copper and zinc) or bronze (copper and tin) is exposed to air, seawater or organic substances such as insect lipids over a period of time. Verdigris is primary a copper salt that is commonly found as carbonate, but it also can be found as a chloride (i.e. if sea water is present) and as an acetate (i.e. if acetic acid is present); and less commonly as a formate, hydroxide and sulphate. Secondary components of verdigris are various other metallic salts, organic and inorganic acids, gases and water. All the components are in an ever-changing and extremely sophisticated chemical equilibrium which depends on the environment.



Historically entomological pins were not made of the robust and non-corroding stainless steel we use today. They may have been made from various alloys, including copper, which at the time, would not have been recognised as potentially causing harm to the specimen. This is one of the major pitfalls of caring for an historical collection. With over 9,000,000 specimens, we could spend our lifetimes (and we do) conserving and curating!

We keep our collection in a temperature and humidity controlled environment, but verdigris can still occur, and decades ago, when we didn’t know as much about collections care, specimens may have been kept in an environment conducive to verdigris forming.

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Pins affected by verdigris (specimens removed - obviously!)


One of our curators, Malcolm Kerley, has indeed decades of experience of caring for historical collections. Here he is giving a demonstration on specimen repair to some MSc Students from Imperial College   

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With all our combined experience and knowledge we gave a demonstration at the last Natural Sciences Collections Association (NatSCA) conference at The Great North Museum in Newcastle to fellow curators and museum / academic professionals on how to repair specimens.


My colleague Alessandro Giusti, who is a Lepidoptera curator and I showed the various ways specimens can be extricated from their damaged pins and re-pinned onto a shining new stainless steel pin which should survive for another 200 years!


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Alessandro demonstrated the amazing specimen exploding machine (or more sensibly put, ‘the de-pinning machine’) which essentially involves passing an electrical current through the pin, which heats up, in turn melting some of the dried fats from within the specimen. This is actually a safe method of removing Lepidoptera from pins, as other methods could damage the body, and more importantly the scales. (It has been known for the specimen to ‘explode’ when the current gets a bit too racy, but of course, that has never happened to us!)


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Here we have the 'Heath-Robinson' of all de-pinning machines.. the NHM, cutting edge science at its most dynamic...


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A typical example of how verdigris affects Lepidoptera



I demonstrated the dry and wet methods of removing beetles from corroded pins. The wet method involves soaking the specimen in heated distilled water for a few minutes (approx. 60-70°C) until it is softened enough to be slipped from the pin.

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A beetle suspended by a plastazote float in distilled water.


Re-pinning involves allowing the specimen to dry thoroughly and then using a thicker pin than the one previously removed to be placed in the same hole. The labels are placed on the pin in the same order and a further label is added to the specimen to record the conservation measure, as well as recording this on our database.

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Here we both are demonstrating to our enthralled audience(!) Notice complimentary butterfly blouse as modelled by me!


We often retain our historical pins  as believe it or not they can tell us a lot about a specimen / collection, for example, certain collectors only used a certain type of pin (Sir Joseph Bank’s Collection used immaculate (and probably very expensive) pins with hand spun heads which today still retain their original condition!


For more information our protocol on Verdigris specimen repair will soon be made available on the NatSCA website.



Beetles; Czech!

Posted by Blaps Mar 13, 2011

Hello Beetlers,


It's been  a while, but things have been very busy in the Coleoptera section this month, and this is because we have all been occupied by getting ready for the big event that is the Prague Insect Fair! (Please see deliberate pun in title, courtesy of Max Barclay).

Yes, that's right, a whole weekend in March dedicated to insects; and if that's not enough, the good entomologists of Europe and beyond, do it all again in October!

This is a really important time for our department and it's been all hands on deck to prepare beetle specimens ready for transport to the Czech Republic.

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Here are a number of entomologists getting excited about insects...


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And here are some more entomologists - this time really excited...

Where to begin? Well, our over-arching aim in the Coleoptera section is to improve the quality of the collection, in terms of identifed specimens, specimens made available for research, and a far reaching geographical spread of species that supports not only the taxonomic research community but also the ecological and conservation community; essentially our specimens can help inform conservation practice throughout the world - and Prague provides the platform for this to occur.


So this month we have contacted all our colleagues throughout Europe to see if they will be attending the fair, and if there are any specimens from our collection they would like to see - this is our loans system, which facilitates world-wide research in to the specimens held in the NHM's collections. Our colleagues put in a request and we 'process' the loan - yes, it has kind of felt like a very long beetle production line this month. The specimens are exchanged in Prague, along with a few beers and some fascinating exchanges on all things Coleoptera no doubt!



The other job is to prepare all our specimens collected on fieldwork trips for transit, in order that they can be mounted, or identifed by some of the most proficient experts in Europe and the World.

It's not an easy job to carry thousands of insects abroad, so we recruit a number of 'carriers' to get our insect stash out of the country, along with a couple of responsible (?!) members of staff.



Here's some interesting statistics yielded from last October's Insect Fair (too soon for this year's results):

Loans for 34 people (56 boxes) were carried to Prague and we returned with 41 people's pre-existing loans in 62 boxes; this meant we met with and exchanged loans with 58 people from 14 countries!


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Here's Max signing off a loan for some expectant Coleopterists.


We returned with 92 boxes of newly mounted material (insects pinned or carded) which made up a whopping 18,428 specimens!

The total number of specimens identified for us by borrowers from our undetermined material was 2,170 and an additional 1,243 specimens were indentified from unprepared material by specialist mounters.
In total 3,413 NHM unidentified specimens were identified on this trip.
As good will it is the convention to exchange specimens between organisations as 'gifts' and so we received 16 specimens (mainly paratypes) and19 new Holotypes - how generous!.  We also received 226 new paratypes from previously unidentified NHM material.



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Here are a number of 'responsible' members of staff and highly respected scientists , with their 'carriers' from left to right:

Martin Brendell, Donald Quicke, Mike Morris, Howard Mendel, Fran Sconce and Max Barclay

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Entomology’s very own Spice Boys, rocking a ‘geek chic’ vibe, thanks to some cheeky accessories and some luxurious matching luggage (I wish I could take credit for such wit, but sadly I cannot. This is the work of the Entomology Department's inimitable PA Esther Murphy)

From left to right: David Oram, Max Barclay, Martin Brendell, Roger Booth, Mike Morris


The best is that the NHM benefitted by 208 new species names to the collection as a result of this trip!


Can't wait for October!


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Photo courtesy of Rafal Ruta
The Coleopterists have left the building!



Member since: Sep 15, 2009

I'm Beulah Garner, one of the curators of Coleoptera in the Entomology department. The Museum's collection of beetles is housed in 22,000 drawers, holding approximately 9,000,000 specimens. This little collection keeps us quite busy!

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