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Here’s a time-lapse video from a project I did using Dermestes lardarius to clean a rat’s skull. The project was aimed at showing different imaging techniques i’d learnt during the third year of my Zoology BSc but I used it as an excuse to access the university’s colony of dermestid beetles. To prepare the rat’s head I removed the skin and the brain. 

Dermestidae of Germany, including larvae and morphological details

Dermestids (specifically Dermestes lardarius) are a favorite beetle of museums and those who prepare bone specimens on a moderate-to-large scale. When maintained as a large enough colony, they’re an invaluable resource in cleaning the last of the flesh and fat from animal bones, and produce a much better final specimen than boiling or bleaching bones does (as boiling causes fat to be absorbed into the bones and bleaching is both dangerous and ineffective).

They’re also used in forensic entomology, as they’re scavengers, and they only appear when (and if) the flesh of a cadaver begins to dry out. They refuse to eat rotting flesh, and they refuse to live in a wet environment, so the weather and climate plays a significant role in determining the amount of time that would have passed before the beetles would have arrived.

Fauna Germanica: Die Käfer des deutschen Reiches, Vol III. Edmund Reitter, 1911.

Larder or Bacon Beetle

Dermestes lardarius

It’s good being a nerd. It took me about 15 minutes to collect, asphyxiate, and identify these two beetles and about 1 minute to figure out that they are a pest that likes proteinus foodstuffs.

I found these two fuckers in my produce bowl on top of the microwave. All I had in there was an avocado, garlic, and ginger root, and none of these were infested, so I think their food source must be something in the pantry above. Most likely my room mate’s part of the pantry above…

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Chicago Field Museum - Dermestes maculatus 

The FM has a great system setup for their dermestid colony.  They have multiple individual tanks (I think 9 in all) in which skeletal remains are processed.  Everything is organized in metal trays so the beetles can easily move between specimens, unlike our museum where we use porcelain dishes that the beetles have a difficult time climbing up, and as a result we have to create bridges between each tray, which can be inefficient.  As the beetles live and die in the Field Museum’s colonies the wire grates are moved up on top of the frass and dead beetles until they reach the top of the tank, at which time the tanks can be cleaned out and reused.  Our system here in Montana is not so organized, resulting in specimens getting buried in the bottom of our colony, sometimes for months or years.  I will definitely be taking what I learned in their dermestid room and applying the system where I can  in the UMZM! 

Pictures:

  • A bird skeleton after freezing off straggler beetles in the freezer
  • The gorilla’s foot - by the way, it is possible that individual was suffering from ankylosing spondylitis, a form of inflammatory arthritis that is genetic in humans. 
  • A small bird (did not get the ID) and Jackson’s Chameleon (Trioceros jacksonii)
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Images used in the bone cleaning project from my last post. The main photo is the head of an adult dermestid beetle using scanning electron microscopy (SEM) with a zoom section of mouth parts. The photos below are as follows: Dermestes lardarius using focus stacking on Helican Remote software (top left), almost cleaned rat skull using focus stacking (top right), head of larvae using SEM (bottom left) and larvae using photomicroscopy (bottom right). 

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