How to protect my mounted insect specimens from ... insects?

Question

I have a modest collection of insect specimens that I caught, prepared, mounted, and dried myself. I'm entirely an amateur collector, so my procedure may be causing me this trouble now, but here's how I preserved them.

1. Killed in the freezer
2. Placed in a sealed container on a dry platform, with a 50% isopropyl alcohol solution under it. This lets the specimen thaw and remain moist, while the alcohol prevents rotting.
3. Kept in container for two to three days.
4. Stretched over foam and held in place with paper and pins.
5. Kept on stretching board for three weeks.
6. Placed in a consumer grade display box.
7. Stored in a dark, dry closet.

It's been a while since I worked on this hobby, but I do like to pull the collection out from time to time and admire it. Today, I was surprised and disappointed to find that some of my best specimens have been turned to dust by a small caterpillar type bug. There are live bugs in my display case, eating my bugs!

I've had these for years without issue, and now I find this. What can I do about it? How can I keep this from happening again? Should my preservation procedure include some other step? How are they even surviving? There's no moisture in there at all!

I'd rather not put something toxic in my display case, as I like to take them out and examine them without the glass in the way. I don't want to be exposed to toxic things every time I look at them. I hope there's some effective, cheap, and safe thing I can do. I've become rather proud of my collection, but it's disheartening to have worms eating them before they've even eaten me.

Here's some pictures of the devastation:

That stain on the right used to be a specimen.

The big pile of dust there on the left used to be a praying mantis. I don't even know what the pile on the right use to be.

This beetle's entire insides have been eaten.

This horsefly looks like it was mounted a hundred years ago.

Apparently moths and butterflies don't taste very good.

The culprit! This little guy and his pals are responsible. You can see exoskeleton sheddings all throughout the other pictures.

Answer 1

I ran into the same issue when collecting bees in a hot, humid environment. As arboviralstated, freezing is a great way to help with the infection but keep in mind:

• It may not kill all of your pests
• It will not keep your specimen from future pests
• It may damage your samples

From the USDA website, you could pretty cheaply use paradichlorobenzene or naphthalene:

Two of the most widely used fumigants are paradichlorobenzene (PDB) and naphthalene, both of which are obtainable in balls or flakes. Never mix PDB with naphthalene as they react chemically and produce a liquid that may damage the collection. It should be noted, that most major collections are now moving away from the use of solid fumigants because of health concerns and in some jurisdictions, it is now against regulations to use some fumigants.

That being said, I used a combination of freezing and then naphthalene (moth balls). It's cheap and anecdotally pretty effective for my purposes. I also didn't access my collection frequently once established, so the health concerns were less of a worry for me.

Definitely worth mentioning that there has been talk that using naphthalene or PDB may damage DNA and hurt DNA extractions on down the road, but this is demonstrably false. That being said, keep in mind these chemicals still pose some heath effects - especially with prolonged or occupational exposure - such as poisoning and carcinogenic risk.

Answer 2

As @picapica says, these look like beetles of the genus Anthrena: museum beetles, furniture carpet beetles or something similar. I'd lean towards furniture carpet beetle (Anthrena flavipes) myself, but this isn't a species ID question.

Your best bet would be to use an insecticide. However, pages 18-19 of Story (1998) "Approaches to pest management in museums" list 15 non-chemical ways to deal with these beetles. Based on this source, I suggest you:

1. physically remove as much of the infestation as you can, then
2. freeze the whole collection (again, as first suggested in the comment by @picapica).

Dermestid beetles like Anthrena are relatively heat-tolerant and the other control methods are more based around reducing the chance of an infestation in the first place. To be effective, freezing may need to be as low as -30°C (generally domestic freezers will only maintain temperatures from −23 to −18°C) and sustained for up to three days.

Once you've got rid of this infestation, some of the other suggestions to avoid reinfestation may be useful, such as sealing or screening possible routes of entry in the cases to stop beetles getting back in.

Nice collection, by the way!

Answer 3

Adding to the allready fine answers, I would suggest to use some camphor. Camphor is relatively inexpensive. I could buy it at the local pharmacy, but depending on your location, it might or might not be available there.

I successfully used camphor to get rid of Dermestids. However, it is much more effective to prevent infestation than to get rid of one.

However, if you use it, you might not want to store your collection in a part of a building where people spend prolonged times. Also, you definitely want to put your collection in a near-airtight container. Camphor evaporates quickly, and an airtight container is important to keep the atmosphere more or less saturated. Glass, of course, is best. Plastic might permeable, and even get brtittle, depending on the specific material. Sidenote: Professional and (very expensive cabinets) use hardwood boxes with a glass cover cemented in the lid, which have the additional advantage of making it difficult for dermestids to get in.

You should apply it using a watch glass, and not let it come into direct contact with both your collections and the material the specimens are pinned on.

Answer 4

Use borates, like for wood treatment. It's not a repellent like moth balls but it will kill them and not be smelly and it has low toxicity.

Borates are also used in taxidermy, especially for controlling dermestid beetles, however salty crusts can develop so, you might have to play around with the concentration- so that you don't use too much.

Also, peppermint and citronella are fine repellents. There are repellent satchets on the market, but you could probably save your money and just get a dram of peppermint oil or (pure) citronella oil (soak a piece of wood- like cedar).

Also, DEET is good repellent. But these repellents won't last as long as moth balls.

Answer 5

Another addition. If you like to avoid chemicals, I recommend using vacuum bags that are meant to store clothes in, which you can easily buy. They are like big zipper bags that close airtight and keep away the pests. This is an alternative to very expensive airtight boxes. To get rid of beetle larvae that are in your collection, you need to kill them. For me, it always sufficed to freeze at -18, but this might not always work. My home freezer is quite small, so I would re-pin the insects to a smaller box, clean up the 'main box' very thoroughly (also removing bottom plate!!!), and after 3 days of freezing put the insects back. Check your collection at least once a year. I have old museum boxes with lids that do not close so well anymore. Since I use vacuum bags I (5 years now) had no beetle infestation so far.

"Apparently moths and butterflies don't taste very good." Well, you were lucky. These beetles love moths and butterflies the most!

Answer 6

I preserve all my bugs in resin. It is an absolute ton of work, and not always guaranteed to turn out, but I have successfully done over 150 bugs.

Answer 7

I like your collection! I am sorry about the beetle tragedy.
I recommend that in addition to killing the ones you have in the collection (freezing) that you put your collection in a beetle proof container to save what is left. That is not practical for a mounted water buffalo but I am sure you can find a Tupperware-type container that can house your collection and prevent beetle entry.

Also: check the rest of that closet. Those beetles came from somewhere. Carpet beetles ate tracks in one of my nice coats a few years back. You might have a colony in the closet. Remove the stuff, shake it out and spray the floor with roach spray.