Beetle elytra

[bugsy]

As some may have experienced, it sometimes happens that the elytra of beetles killed and/or preserved in liquids (e.g. alcohol) will spread apart as they dry.

Does anyone know any methodology to prevent this from happening or to fix specimens where this has occurred? I've tried relaxing specimens so I can firmly keep the elytra pushed together as they re-dry, but they always seem to spread apart again.

Any help appreciated.

[58chevy]

Place a pin against each side of the abdomen to hold the elytra in place as the beetle dries. Make sure it is completely dry before removing the pins.

[KKarns]

Most problems can be avoided, and it starts with how the beetle is killed. Specimens placed directly in alcohol will be brittle and often the elytra pop open. No real reason to use anything other than ethyl acetate for killing Coleoptera. The beetles can remain in the killing jar for a reasonable length of time and be totally relaxed when removed for preparation. Most beetles killed in ethyl acetate can also be transferred to alcohol for long term storage with no problems. A few taxa may have the elytra pop open if stored in alcohol for an extended period of time. Choice specimens can be removed from the killing jar and immediately field pinned when on a collecting trip. The beetles can then be relaxed and prepared as usual with no risk of the elytra opening upon drying. Freshly killed specimens can also be papered and relaxed up to many years later with no issues. To be safe on large species bracing the elytra with pins, as mentioned by 58chevy, can also help assure a perfect mount.

[bugsy]

Thanks for the information guys.

I know alcohol is not the best for killing beetles. Unfortunately, I have large amounts of collected material over last 15ish years stored in alcohol. Generally I've not minded the drawbacks of alcohol, but I've recently become more interested in carding specimens so I'd like to be able to get some nicer looking specimens.

I'm assuming the problem with the elytra is due to the muscles becoming excessively stiffened from the alcohol. Are there any methods to thoroughly relax such specimens? I'm going to try an extended time in relaxing container but I'm open to other ideas/methods. I saw on extreme-macro.co.uk a method using pepsin/HCl to relax very stiff beetles. Anyone tried that? Alternatively, maybe soaking in Barber's Fluid?

[kevinkk]

I have a small bottle of Barber's fluid- I think you'll need some luck to find it now, since it came from Biouip.

Well, you can learn something nearly everyday- there is a recipe online for the fluid, apparently developed in 1934.

[bugsy]

Yeah I used a recipe to make up a 100 mL bottle when I was in grad school. Its very useful, though I've barely used any of it.

[HowardMathis]

Use of fixatives: Fixatives such as ethyl alcohol or acetone can help strengthen and secure the elytra in position. Before using, consult scientific sources or insect dissection specialists for recommendations on the use of fixatives.
Use of glue: Some researchers apply a very thin layer of glue to the surface of the elytra to prevent its disintegration. However, care should be taken not to damage the specimen and not to use too strong an adhesive, which can distort the structure of the elytra.
Use of Support: When beetle specimens are dry, small stickers or other materials can be used to support the elytra in position until they are completely dry. This can help prevent them from disintegrating and keeping their shape.

[Chuck]

I've experience a similar (or same) with Catocala moths. It's the same muscles, so I'd think it's the same issue.

Catocala dispatched by dropping (knocking) into isopropyl alcohol will stiffen the wing muscles such that they cannot be set. I've found no method to subsequently relax these muscles.

[AKColias]

I've experience a similar (or same) with Catocala moths. It's the same muscles, so I'd think it's the same issue.

Catocala dispatched by dropping (knocking) into isopropyl alcohol will stiffen the wing muscles such that they cannot be set. I've found no method to subsequently relax these muscles.

Pepsin can be used for relaxing very stiff specimens where the set muscles have become too hard to be relaxed with Acetic Acid. Read more at http://extreme-macro.co.uk/chemicals-fo ... z4c5n0ZHnx

[bugsy]

Interesting paper that touches on relaxing techniques. Includes a modified formula for Barber's solution without benzene.

https://www.researchgate.net/publicatio ... Formicidae

I'm going to try the pepsin technique to see how well it works.