Written by Nancy Miorelli
The internet is chock-full of advice for collecting and if you’re looking to build an insect collection but can’t take a formal class, there’s lots of available help.
I myself, have a YouTube series dedicated to helping budding entomologists put together their first collections.
But there are always those awkward middle steps that seem to be left out of the conservation. I don’t think anyone means to, it’s just we’ve all found our methods that we like the best. However, for someone just starting out, those steps can be really important. Since it’s almost spring here, and people might want to start collecting, I thought this would be a good time to write about this.
I received this series of questions asking about all those bits that aren’t usually mentioned in collecting tutorials.
Before we get started, insect collections are used for many purposes including outreach and research. I won’t be discussing the reasons for insect collections in this article, only how to do it. If you’re interested in why entomologists kill insects, you can read one of our previous articles here.
1) Plaster or Plastic?
The plaster kill jar just holds a charge longer. The Acetone (or Ethyl acetate if you’re fancy) seeps into the the plaster and lasts a lot longer than just a cotton ball in a plastic jar. Even if you don’t use the jar with the plaster, I’d suggest always using glass – like a jelly jar or a mason jar – because the acetone or ethyl acetate can melt the plastic and your insects can get stuck in it. Some newer killjars, like the ones sold on bioquip have a canister that secures into the top of the lid that contains the liquid and the substrate. This is helpful, because, while it’s not so much of a problem for the cotton ball, the plaster can take a long time to absorb all the liquid. The canister at the top holds everything so your insects don’t get all wet and stuck to the bottom of your kill jar.
As for acetone vs ethyl acetate, the ethyl acetate also holds a charge a bit longer than the acetone, but acetone is really easy to get and cheap because you can just grab some nail polish remover. If you’re just going to go out collecting for an afternoon every once and a while, a cotton ball/acetone gets the job done. If you want to make a long term thing of it, I’d suggest the plaster/ethyl acetate which can be found on the BioQuip website. https://www.bioquip.com/
You don’t have to use kill jars. One of the drawbacks of the kill jar is that it almost instantly kills things. I really only used them to subdue angry stinging things. The kill jar kills all insects really well, but can cause problems for insects with predacious diets. The oils and fats in their digestive system seep through their body when they die and discolor the exoskeleton. One way to help prevent this is to let them live long enough to poop and cleanse the system. Then you can put them in the freezer and pin them when it’s most convenient.
2) Caught them! Now what?
I always put mine in the freezer. You can store your insects in ethyl alcohol, but if you keep them there for a while, then want to spread the bugs , the alcohol can make them brittle and hard to move around. This can make it easier for your insect to break or become damaged. The freezer preserves them without the insects becoming too brittle, so it’s easy to pin them and move all their legs and wings around to make them look nice in a collection.
3) Butterfly Triangles
Butterfly (Lep) triangles are triangluar pouches made, usually out of paper, to store butterflies. You can use wax paper, or buy expensive (and not really necessary) glassine envelopes. You would use butterfly triangles for any kind of Lepodoptera (butterflies/moths). It’s mainly to keep the butterfly flat and prevent it from damaging the wings and/or rubbing the scales off. You can put the whole thing in the freezer and leave the butterfly in there until you’re ready to pin it.
Here’s a video about how to make butterfly triangles.
Alternatively, I tend to use ziplock beading bags for my bug catching. I like to stay really organized, so I put each bug in one bag. I then label the bag: where I was, the date, and the habitat I took the bug out. Then when ID it, I’ll write the ID on the bag too. You can use the ziplock bag for butterflies. I was told that, because the bags don’t allow airflow, the butterflies can mold inside, but I never had a problem with this. Some people just like to get a big ziplock bag and throw everything in, but I can’t handle that amount of chaos.
I also carry a hard plastic pencil case around me in the field in my backpack. I put my bags of bugs I’ve collected in the pencil case, and when I get home, slide the whole pencil case into the freezer. This prevents the bugs from getting damaged in the field. If you get them around the beginning of the “back to school season” you can get them for like a dollar.
4) Freezers vs Alcohol
Insects stored in the freezer are easier to move around later if you want to pin them. However, people who might want to do genetic work and need the DNA to not degrade will store the insects in alcohol. That being said, anything can be stored in alcohol if you don’t want to pin it right away or ever.
There are also a lot of insects/arthropods that don’t preserve well outside of alcohol. These include arachnids (spiders/daddy long legs/scorpions/etc…), soft bodied insects (termites, neuroptera [lacewings/dobsonflies], stoneflies, mayflies, caddisflies, fleas, lice…), and larva/nymphs (caterpillars, maggots, dragonfly nymphs…). If you don’t store these insects in alcohol, they’ll shrivel on the pin. In some cases the body can recede completely into the thorax. I’ve had some luck counteracting this, if you store your insects in acetone for a few days before you pin your insect. The acetone replaces the water in the insect and they dry faster.
Some people store things in alcohol that are really too small to pin, or are fragile and might break if pinned. If you want to pin soft bodied insects, you can soak them in alcohol/acetone first, then pin them and it helps them retain their shape when they dry. Otherwise, oftentimes the abdomen shrivels into the body cavity and it looks like half your insect disappeared.
5) Relaxing Chambers
If insects aren’t stored in a freezer or in alcohol, the insect will dry out. Their muscles become stiff as they start to dry. This is the process that makes insect pinning effective, however if they dry out before you can pin them, they cannot be pined and break very easily. People will use relaxing chambers to try and rehydrate the specimen so they can attempt to pin it. You can avoid having to do this by just putting your insects in the freezer when you get home. Most people just make their own out of a solo cup, and some damp cardboard/paper towel. You just have to make sure that your insect doesn’t mold.
This person uses a Tupperware, but it’s basically all the same.
6) Freezer Time
How long you store the insects in the freezer depends if you’re using the freezer to kill them or not. If it’s just storage however long you need. If you’re using it to euthanize the insects, at least 24 hours. Some insects are freeze tolerant and will wake up. Some of the bigger and heartier grasshoppers/moths you’ll probably want to leave in there for a few days.
I personally use the freezer to euthanize the insects. It seems to me, the most humane way to go about the process. Since they’re exothermic, their metabolism and everything slows down until they just go to sleep.
7) Thaw Time
Depends on how big the insect is. Little leaf hoppers thaw in a few minutes. Big moths might take 15-20 minutes. Just try and move them around. If they’re still really cold and resistant to moving then let them thaw out for a bit longer.
8) When Can You Pin the Bugs?
If you use a kill jar you can pin the insect immediately after. Just take the insect out and wait a few minutes before pinning. Sometimes they seem dead, but aren’t really. I usually put everything from the kill jar in the freezer for a day just to be sure. I had a wasp wake up on me once and it’s not something I’d like to repeat.
In some cases, extra measures have to be taken when preserving insects. For really large tropical insects, oftentimes the guts have to be removed so the insect doesn’t mold. I don’t have any experience with this, so if anyone does, feel free to chime in in the comments below.
I hope this was helpful! If you guys have anymore questions feel free to leave them in the comments and I’ll be happy to tackle them =D If you have any advice too, please leave it below in the comments! This kind of stuff you usually learn about in class, so it can be hard for people to find this information =)
Here’s some collecting bloopers. Enjoy =P
Any tips for field collection during long trips? For example, backpacking without access to freezers or long term storage?
Alcohol. Put everything in alcohol vials. Or if you want, you can just sort everything later and just bring a big jar of alcohol. It’s not uncommon for entomologists to store insects in their beer or vodka in a pinch.
Thanks so much for this article. Quick question, when you store your insects in the freezer what exactly do you store them? Bags, plastic containers etc? Also, how do you deal with the condensation that the freezer may cause. Thanks 😀
I usually store them in ziplocks. Although if your household inhabitents dont like seeing dead bugs in the freezer then hard pencil cases work great. The condensation isnt a problem. The bugs just dry off. =)
Thank you so much :D:D
I have a couple of butterflies in my freezer and would like to find a way to show them. Perhaps in a glass ball or frame. Where would I go to have this done? I am in Tampa Florida
I’d suggest a shadow box from your local hobby store =)
If they’re pinned already you might see what a professional framer can do.
Should we thaw the frozen insects in relaxing chamber before pinning? If so, how long??
Should we thaw the frozen insects in relaxing chamber before pinning? If so, how long?
Is it ok to just thaw them im room temperature?
You don’t need to put them in a relaxing chamber if they’re coming from the freezer. Just let them thaw to room temperature and that they’re soft enough to move their legs around and such.
This is a really well-written article with excellent advice. I am about to start identifying some beetles caught by another member of faculty that were stored in alcohol for >6 years. If possible we’d like to pin a few voucher specimens. Do you have any advice on how to rehydrate and relax them? What techniques work best? How long does it take? Thanks Barbara
Anything that has been stored in alcohol that long will be hard, so the first question I have is is it necessary to rehydrate them? Or can you pin them and still see everything you need (tags and antennae).
Or can you ID them and then pin them?
The rehydration chambers (whether you use cups or Tupperware, paper towels or sponges) all work the same way so your biggest thing is to check every day and make sure your beetles don’t start to mold.
Hope this helps!
I’m going on a cross country road trip and wanting to collect insects and pin/spread them when I get home. Will storing them in alcohol for 3 weeks make them to hardened and difficult to pin and display? Thanks for this article!
Hi, I’m glad I came across your page. I found a dead stag beetle that I placed into the freezer yesterday, along with two dead cicada killers. The beetle was on its backside and not moving when I found it, but since the legs/ pinchers still moved, I placed it into the freezer right away. The wasps were caught and saved by the local exterminator at my request and were euthanized by the freezer.
I have not pinned any of these yet, but plan on removing from the freezer to do so over the coming week. My plan was to place the bugs into resin. I know about pouring in layers, silvering, etc, but being a first time resin user, I would appreciate any tips. I’m going to do a test on the spare cicada killer as well as a few spare small wasps I found locally.
I know the bugs have to be dried as thoroughly as possible. For extra dryness, after pinning, I was thinking of placing the pinned beetle and killer into something like a cookie tin, along with some silica gel, and a couple of moth balls, closing, and then leaving that way for 2-3 weeks.
Anyway, your thoughts would be welcome. I’ve seen quite a few videos on resin embedding, but few on the actual recommended drying processes leading up to the resin process.
Thanks in advance,
I’ve ever actually resined insects before.
Leaving the insects to dry them out would be a really good idea. I know of some people who lightly bake them in the oven and other people who leave them in their hot car for a few days. Sorry I can’t be more help.
The most important thing for the resin is to add it layer by thin layer. A lot of people get impatient and just dump a huge layer on but then then you get air bubbles.
If any of your insects are iridescent, note that the acrylic can possibly change the color. The acrylic might fill the microstructures (as with morphos) or change how light is reflected out. I’ve seen Eupholus weevils turn silver in acrylic becuase it just changes how light bounces out of those structures.
Thanks, Nancy. Because of the uncertainty of the resin method, I decided to abandon it for now. Insects are currently being stored in either sealed plastic containers containing both silica gel and moth flakes, or inside glass domes for presentation purposes. I’ve been drying anything caught for several weeks inside a toaster oven first with temp set around 125 F. Most butterflies are ready to leave the oven after 3 days, but I usually keep them in their a week.
The domes have been a problem. When they are purchased, they come with a wooden base, but unfortunately the base is porous. If silica gel or moth flakes are placed within the dome, the former turns pink after 24 hours and the latter smells strongly even if the dome base is sealed to the wood with silicone. I’ve tried coating the bases with several layers of shellac….. this can work for future domes but not for the ones I already created. It is too much trouble to try and detach everything glued down with the existing domes (so that I can shellac coat the top side of the base), plus the butterflies would be easily damaged, so I am looking at sealed acrylic canisters of the proper size for the domes I cannot coat entirely.
I also have two small shadowboxes that also had a wooden outside frame. The complete frame was shellac coated several times, and then the back was replaced with a thin metal seal. Everything was glued together with silicone once the shellac dried. With those, since there is a complete seal, the silica gel and moth flakes inside do their job and don’t smell.
First I know this post was years ago this info might be use to others. I have never encapsulated inside in resin. I’m providing info on resin and how it might be used. Use a type of resin designed for “river table” (best for thick and long cure time) or slow curing casting resin (use for small or thinner pour) this type of resin allow for thicker pour and slower cure, Never use hardware resin their design for super thin layer coating for table and cracking issue with cracking if poured to thick. The advanage for the “river table” and “slow curing casting resin” is that it allow for all bubbles to surface before hardening and their also designed to not crack due to the exothermic reaction as it cure and harden. Problem with some resin and multiply layer is that something these layers back be seen. For small insect that can be done is a single or 2 layer without special equipment like a vacuum or pressure chamber. Alumilite resin is a very popular casting resin but even their slow still require a pressure chamber to have bubble free casting (work time is 12min max and demold time 2-4 hours) . I have not used “Liquid Diamond” but it as a 1 hour work time and 24 cure time and does not need special equipment like a pressure chamber. Check out reviews on youtube and check out what is the current and best resin people are using for “river table”, Casting resin, and resin for woodworker.
I have an imperial moth and it’s on the large side I wanted to know if I need to gut it or not. I haven’t been able to find any information about dealing with large type moths.
Thanks so much.
You probably don’t have to. Just make sure you keep it really dry.
I think gutting is more necessary in large beetles.
Glad I found this site! Have a quick question; so yesterday I saw a dragonfly on the path, she was dying and I put her somewhere safe in the bush, today she still there and passed away peacefully. I picked her up and she is now in the freezer. I won’t be able to do anything until the 8th of August as I am away, but when I come back I would like to take some high quality pictures, so I am not too sure what I should do next? Should I defrost her and then deep her into acetone, then let here dry… then inside an air sealed frame? The priority is to take pictures, especially macros, then I am tempted to keep her. Please advise I am a first timer. Thank you 🙂
Dragonflies are tough because they’ll lose their colors over time.
I’d defrost her, and then take some pictures of her.
To save her for long term storage Id then dip her in some acetone to break down the fats. Then pin her up, and store her in a shadow box away from sunlight or splurge on UV protective glass.
Thank you Nancy, I appreciate your help!
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Do you think I should remove the guts from cicadas before pinning them? I am just getting into this and want to know how to keep my specimens looking beautiful and accurate for as long as possible.
You shouldnt need too =)
Would the guts need to be removed before pinning an adult female giant prickly stick insect?
If so, what’s the best method to do this without damaging the specimen?
Hi I am making a bug collection for one of my classes but i have a 3 day road trip to get back to school and all of my bugs are currently in individual bags in the freezer and i don’t want to pin them yet so i was wondering what you would sugest for the best way to travel with them. Also most of what i have in the freezer are moths and i was wondering if you can keep moths in alcohol or if that would ruin them? Also to thaw the insects can i keep them in the bag or should i take them out in the open?
The problem with putting bugs in alchohol is that they “freeze up” and the muscles become stuff. Moths tend to lose to lose their scales. I think for three days if you just kept them in a tupperware they would be okay, but you would have to make sure that they don’t dry out.
Is it possible for you to pin / mount them before you leave and travel with them in a shadowbox?
Thank-you for all the great advice! I am just starting a insect collection for a college course and I was wondering: Are there any issues with freezing over long periods of time? For example, if I were to store my insects for a few months before creating the collection, would there likely be any damage?
Thanks for your time!
A few months is fine =) You won’t have any damage. I did the same thing for my collection
Ok that is great news 🙂
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I think I’m in the exact same class as Dave up there, but I have a few butterflies that I was too nervous to pin the day I caught them. I have a swallowtail, a luna moth and a white Tiger moth (just now realizing that I have more moths than butterflies). How long would you say to rehydrate them before I can pin them? Their wings are folded. Also, I have a leaf beetle in alcohol. Can I still pin it, or would it be too brittle? It’s been in there a few days but I would really like to pin it
You can pin the beetle.
As for the leps, gently try and move the wings or the legs. If they move around easily go ahead and pin it. If they d9nt you’ll need the rehydration chamber. Usually a couple days but check it every day to be sure. It’ll depend on where you are and the conditions. I’d you’re in the deserts of Arizona it might take a while. I’d you’re in humid Georgia it should free up within a day or two. The most important thing is to keep it from molding
Thank you so much 🙂 I’m rehydrating them now and they seem to be getting more flexible. I pinned the beetle. I like it so much more than in the vial of alcohol. Swallowtail butterflies are my favorite so I really want these to come out nice.
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Hello. Today I found a praying mantis that had just died, in perfect condition… I kind of have a nack for finding recently deceased insects… I would like to put him in a shadow box to place on my wall. Can I pin him because he has a soft body, or will he deteriorate? Also, someone mentioned to me about spraying him with lacker, is this a good idea?
You can just pin him. I wouldn’t suggest spraying him with lacquer and I don’t know why this person suggested it to you.
I’ve been collecting butterflies and wasps for the last six weeks now with many caught with a homemade hanging butterfly trap. My take on kill jars is mixed. Out in the field, I discovered that the pinching method often suggested pretty much does the trick and no kill jar needed. At home, for the wasps for which obviously I can’t do the pinching method, I use a mason jar. I slightly wet a small piece of paper towel with ethyl acetate, then quickly anchor it on the jar’s inside lip at the top. The wasps are already in the jar, but with practice this can be done quickly and the bugs don’t escape, plus I might firmly tap the jar on the ground a few times to dislodge the bugs from near the top. I’ve resorted to this type of makeshift kill jar because I find way too much “sweating” of the plaster jars. I have even left the jar opened for a day or so until all the ethyl acetate smell is gone, but after resealing the sweating is back especially if temps are warm. This isn’t so good for butterflies as it could mess up their scales, with beetles and wasps it isn’t as much of an issue obviously.
The one thing I find the most difficult to preserve are caterpillars! Monarch caterpillars especially! I have been trying to create the life cycle of the Monarch in a small dome for young kids to look at when they study butterflies. Both the Monarch caterpillar and chrysalis turn black shortly after starting the drying process. For the chrysalis, this was finally solved by removing the internal contents after several days, flushing out the interior with alcohol, carefully refilling with silicone, and then spray painting the chrysalis to the approximate color it had been. For the caterpillar, inflation has been attempted several time as well as refilling the cleaned out body with silicone but usually will turn black within a day. My understanding is that the turning black has to do with the breakdown of internal proteins, so I recently tried “poaching” some frozen ones by dropping in boiling water for a minute to hopefully “fix” the color. I haven’t yet tried to dry the poached ones (still in freezer) but so far color hasn’t changed other than initial color shift and fade from the poaching process (was expecting that as I read it would happen). I have another caterpillar drying using a freeze drying method I read about by placing the caterpillar under vacuum… that still has another week to go before it is supposedly dried. What troubles with caterpillars… recommend folks just stick to easily dried insects like butterflies!
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I have just caught and froze a pair of blue mud daubers. I have put them into yogurt cups and into tupperware and I am storing them in a freezer. I need them for an entomology course with my wildlife class in September and I was wondering if they will last in the freezer until that time?
Hi Nancy! I would like to ask what is the proper way of collecting insects without killing or stressing them out?
It depends on what you want to catch!
This is such an old post I hope I get a response. My 10 year old daughter loves all animals and bugs. She wants to become a Veterinarian when she grows up. She loves to learn about everything in nature and we encourage her to do so. We were just on vacation and she found a complete Dragonfly. It is completely dried out, and she would like to start collecting and pinning different insects, moths, butterflies, and other creepy crawlies LOL… What should we do with the dragonfly until we figure out how we are going to store them. I read a lot about freezing. I also read about the relaxing box. Also placing bugs in alcohol. Does everything need to be placed in Alcohol or is that just a way to store some bugs in small jars? Or used to send them off to their deep slumber? I also read about moth flakes. Those are to prevent molding? I was also wondering if you can use a light coating of polyurethane would work if you wanted to display them in something similar to a terrarium that mimic’s their natural environment. (Not a living terrarium.) Thank you for any advice. I hope someone still reads this LOL… Angi
Thanks for the great info! I am collecting bees this spring using blue vane traps with soapy water. Do you think it would be possible to freeze the bees for storage and wash them afterwards? or would freezing them still-soapy pose a problem?
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