Wednesday, October 10, 2012

The Inexplicable Mojo of Tiger Beetles.

mo - jo - noun.
1. A magic charm, talisman, or spell. 2. Magic power.

Comments on Curation.

With their long spindly legs and thread-like antennae, curating tiger beetles, particularly Cicindelini, can be the ultimate challenge of one's dexterity, eye sight, and patience. When cleaned (degreased), pinned and labeled properly, the intrinsic beauty of a schmitt box or museum drawer of tiger beetles can be impressive.

Regrettably, I have borne witness to many a tiger beetle collection spoiled by poor curation. Hence, the impetus for the present series of posts.

After month's of planning and waiting, you've finally reached that mecca of tiger beetles that has eluded you. You've only had a single specimen of an endemic species that occurs here that a colleague gave you - just to whet your hunter-gatherer instincts. The summer monsoon has just soaked the locality within the last day, the sun pounds down on you and the humidity is perfect - for tiger beetles, anyway.                                                            
So, let's begin right there in the field ...

I collect specimens straight into double-seal vials of 95% ethyl alcohol (isopropyl or 70% can also be used). Several vials will easily fit in a cargo pocket, safari vest or backpack. Thus, hundreds of specimens can travel safely being held in a liquid medium, and, if need be, stored until time permits to begin the degreasing process. I also use the same system when collecting New World Acmaeoderini (Buprestidae:Polycestinae).

Before storing, I insert a small piece of paper with basic locality data written in pencil into the vial. Other collection and locality details are jotted down in a field notebook for later reference.

To secure the vials while en route, I use a vial tray adapted to fit inside of a wooden cigar box ... 

A piece of opened-celled rubber foam (upholstery foam) fits between the vials and box lid minimizing any jarring or rattling during transport.

Okay then, ... so what is "degreasing" and why is it necessary?

Degreasing, as it applies to adult tiger beetles, is the process of removing internal lipids (body fats) by placing specimens in a series of cleansing "baths" using a solvent, for example, Ether or Hexane.

If not removed, over time, these internal body fats may leach out to the exterior surfaces of the pinned beetle resulting in a badly discolored specimen sometimes to the point of obscuring the beetle's vibrant colors and distinctive maculations (markings). The hair-like setae will become matted as well.

In a nutshell, here is my process using petroleum ether:

I have found that it may take up to three, rarely more, sometimes fewer, degreasing baths of 7 to 10 days each to clean specimens thoroughly. After that interval, the ether will gradually discolor from the removed lipids. At this point, the liquid needs to be replaced with fresh ether. Continue this process until the liquid remains clear after the 7 to 10 days. When the series of degreasing baths are completed, the specimens can remain in the vial awaiting pinning and labeling. If longer storage is anticipated, return the specimens to alcohol.

A colleague, using Hexane, informs me that his specimens are fully degreased in about 3 days. In a pinch, "white gas" (Coleman lantern fluid) can also be used. I experimented with it years ago but didn't care for the final results.

NOTE. When using any of these highly volatile solutions use common sense and safety precautions:

  • Store containers in a cool dark place. 
  • Always use in a well ventilated area.
  •  Keep out of reach of children - and some adults.

Next time, how to properly pin, set, and label your degreased specimens.

                                                 © Delbert La Rue 2012. All Rights Reserved.


  1. Great post. Everybody has their own variation on this theme - I use ethyle acetate (because I can get gallons of "waste" from our protein sequencing lab).

  2. Thanks, Ted.

    I began using ether from an ancient article in the journal, Cicindela.

    Ethyl acetate, huh?

  3. Any organic solvent will work - the choice depends more on availability and safety. Ethyl acetate vapors have relatively low toxicity and flammability and, for me, is readily available. Hexane and acetone are also commonly used, although the latter will dissolve nylon pin heads if used to degrease pinned specimens. Many people shy away from ether because of its extreme flammability.

    p.s. your word verification is a real obstacle to leaving comments...

  4. Agreed. Ether or hexane have always been readily available for me.

    Thanks for the tip regarding word verification. I guess that is the default on Google Blogger. I had no idea since I never comment! I've changed the setting to "No" ... hope that makes commenting easier.

  5. Delbert, Does the petroleum ether leave the specimens stiff? I had a collector detail to me his procedure for degreasing and you have to pin the bug ahead of time. He uses acetone which supposedly doesn't effect the pins if the heads are above the surface and they are in the vat for a short time. A jig is used to pin the specimens and keep them under the surface. It works nice but is a pain... So, how does the petroleum ether work? (Time for the post on properly pinning and setting!) Thanks! Paul

  6. Hey Paul,

    While the method you described works, you're right, sounds like a real pain and a lot of unnecessary trouble.

    I leave the specimens in their collection vials, drain the alcohol, then top off with petroleum ether. YOU DO NOT HAVE TO PIN FIRST. When the ether remains clear after the series of "baths" and you're ready to pin,... with forceps, I pull one or two specimens out at a time. Insert the pin, check height with pinning block, set pinned specimen on a piece of styrofoam, then start setting legs and antennae using insect pins to hold them in place. They dry fairly quickly but I leave them set for three or four days to be sure. Yes, they dry stiff. Take your time, be patient.

    I have always used pet. ether and it has worked great for me. Look at the photos of my tiger beetles posted in the blog. Ted said he uses ethyl acetate, and others I know use Hexane. All can be purchased on the internet, like Ebay.

    I'll get to that "Pinning & Labeling" post some time soon I hope. Most of my computer time is being spent trying to finish up a manuscript on new Polyphylla.

    Let me know if you need help with your tiger beetles. You can email me directly as I'm not checking my blog very frequently now days.

    Best wishes, have a good holiday season, ...