Theresa Howard showed us the collections stored in the Cocoon and this gave us an overview of how the dry and slide entomology collections are kept. This photo shows four levels of protection for these pinned specimens.
We started the day with a tour of the Coleoptera (beetle) collection with Beulah Garner. She showed us a recent acquisition of beetles from someone’s collection that was going to need re-curation.
The beetle collection has not yet been moved to the Cocoon, but this room is noticeably less humid than the public galleries and the specimens are in neoprene sealed cabinets.
Beulah showed us some amazing historical specimens collected by Joseph Banks, and a drawer with a map of beetles collected by Darwin. The red circles in the drawers means that it is a type specimen. The one pointed at has Banks’ handwriting on the label. These specimens are not part of the main collection, but are kept separate due to their historical value.
Interestingly of all the beetles Darwin collected, none were described by him, they were all sent out to experts and then came straight back to the museum. Darwin’s expertise was barnacles.
We then got hands on, and sorted some specimens from Borneo that had been caught with a flight intercept trap.
We were looking for beetles and bugs (Hemiptera), these specimens are from a high biodiversity area and there are perhaps new species in here.
He showed us around the Darwin Centre, where the spirit collection is kept, these collections are also in a temperature controlled environment, as it reduces evaporation of the alcohol.
The entomology specimens are generally double jarred in a glass tube, then stacked in a le parfait jar, traditional ground glass jars are preferred, but they are prohibitively expensive.
The alcohol used is 80% Industrial Methylated Spirits (IMS) this is a combination of methyl alcohol which is poisonous and ethyl alcohol. 100% Ethanol is also available but is much more expensive as you have to pay duty on it, because you could drink it if you really wanted to.
This picture illustrates the variety of jars used in the Arachnid collection, the yellow paint on the jars means that it contains a type specimen.
Mammals can also be kept in spirit, but if the alcohol content gets too low, the bones will start to dissolve. (be warned Freshers)
The majority of entomology specimens are pinned. Unfortunately the historic techniques, cork, brass pins are not so good for long term preservation.
The current practice is to use polyethylene foam (aka plastazote) and acid free interchangeable unit trays. This makes lay out flexible and it is possible to remove a small group of specimens without disturbing the rest of the drawer.