Degreasing Specimens

by Scott Smith

Hi Bill,

The following is a method I have found useful in recovering a greasy or "oiled" specimen.

Many species of Lepidoptera, especially large moths, have a significant amount of stored body lipids (fat) in their abdomens. These lipid cells often break down into a liquid after death. This fluid fat leaches out of the abdomen and onto the wings and body scales; this can sometimes ruin an otherwise perfect specimen.

The goal here is not to regain 100% of the specimen's original glory (this is seldom the case), but rather to make the best of a bad situation, generally getting back about 85-95% of the original color and scalation without causing much damage.

This male Hylophora gloveri is about as badly "greased" as you'll ever see. Here, along with some photos, are the steps I used to de-grease him.

1) Photo of a badly "greased" male H. gloveri, unmounted, right out of an envelope; you can process spread specimens the same way. Leave them on their pins and follow directions.

2) Removal of the abdomen, I pry it away gently with an insect pin, scalpel, or small scissors...be careful with the abdomen! You will need it later!

3) Fill a small jar with 100% Acetone (clear only) and add the separated abdomens. Put the lid on and let them soak overnight (several days for large species).

It is fine to have several abdomens soaking in the same jar.

4) Fill a metal or glass pan with Acetone to a depth of 1/2". Lay specimen in liquid (don't worry, it evaporates 100% later). Soak no longer than 1 hour! If you soak too long, the Acetone may break down the fatty tissues that hold the wing scales to the wing surface. Short soakings are not a problem.

Remember that Acetone de-hydrates; it removes all moisture from the specimens! Treat specimens that are "wet" with Acetone as if they are bone dry or breakage may occur.

5) Lay the specimen on a clean paper towel to dry (give it an hour). Inspect for oily spots after the specimen has dried. If you find any greasy spots, put the moth back in the Acetone and soak for fifteen minute intervals, repeating process until no oil shows on the dry specimen.

6) After the Acetone has evaporated from the specimen, you can relax it as you normally would a dry specimen. I inject the thorax with hot water using a syringe. The hot water almost instantly makes them flexible enough to begin spreading. I allow about 30 minutes before getting started.

Another relaxing technique is to place the specimen in a tightly sealed container, having a high humidity, for about three days. Lay the specimen on top of dry paper towels over a layer of bubble pack over some moist paper towels. This will keep the specimen out of the water but in a very humid environment.

I choose to spread most species upside down on a balsa wood board. This method was suggested by a friend and, after much hesitation, I started using it. I have spread on many surfaces, some foams are okay, but balsa seems best to me. Suprisingly I have not seen any problems with scale loss, and the antenna are much easier to spread.

Pinned plastic strips are used to hold wings in position. Wings are moved by using pin tip below a tough wing vein rather than puncturing wing.

6) The next day (or when abdomen is done de-greasing), dry the abdomen (at least one hour) and glue it to the thorax in its original position with silicone. Use pins to prop it in place as needed while it dries.

7) Once the glue has dried (overnight), use short puffs of breath or VERY cautiously use a compressed can of air (like you clean computer key boards with) to fluff up the body and wing scales. NEVER FLUFF SCALES WITH A PIN! This will dislodge and remove scales. The breath or compressed air works fantastic! Use the compressed air with only a partially depressed trigger to control air pressure; full blast will blow the wings to bits!

8) To prevent wing damage on fresh specimens, it is best to let them dry a few days on the spreading board to stiffen up a bit. Then, before the oil has a chance to leach out onto the wings, carefully pry off the abdomen and soak it on its own. After the specimen is dry, glue on the nice clean abdomen. The fluffing of the scales will hide most of your handy work.

Thanks for the article, Scott. Congratulations on a finely restored specimen.

9) Don't be shy! This works on Luna's to Bird Wings, there is no limit, Acetone is your friend.

That's it! Go get an oily Cecropia and give it a whirl.

Here are before and after pictures of the detached abdomen. I had to lighten the image of the greasy abdomen (left) quite a bit just to make it recognizable.