Chemicals For Insects

by Johan J Ingles-Le Nobel
Last updated August 31, 2017

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Entomologists and insect stacking photographers use various chemicals in their work and many can be bought easily through eBay if you're in a country where they're not available to individuals.

Toxic chemicals require special care in use and all killing and storage jars should be marked clearly POISON, airtight and breakage resistant.

Toxic chemicals require special care in use and all killing and storage jars should be marked clearly POISON, airtight and breakage resistant.

Beware, in the context of entomological preservation there is no 'one-size-fits-all' method for treating specimens - smaller specimens require different concentrations and/or preservatives to larger specimens, whilst soft-bodied or scaled specimens present unique challenges of their own.

Hair Matting

Hair matting on cleaned insect specimens

Hair matting on greasy hair, a common problem.

Hair matting is a common problem when preserving and cleaning specimens; having tried a variety of solutions I can confirm that there really is no known solution other than doing it the old-fashioned way, combing out the hair. It is thought that hair matting occurs because of various greases etc that come out a body after death but degreasing agents don't appear to help much, if at all. Your help with this would be appreciated as it drives me round the bend!

Insect Preservation Chemicals and Solutions

Ethyl Acetate, Acetone (Nail Polish Remover)

Easily sourced killing agent with good anti-rotting preservative properties and low toxicity to humans. But can also cause a killing jar to 'sweat' inside sometimes destroying specimens. Use glass container (solvent, eats plastic). Versatile chemical that is also used to relax, preserve and declump but will still leave hairs matted.

Ethyl Alcohol (Ethanol)

Often abbreviated to EtOH, Ethanol is used as preservative at 70-90% for soft-bodied specimens, used in a killing jar for hard bodied specimens. Some insect taxa and stages, however, don't do well in alcohols. For example, some larvae will discolour (darken) if killed in alcohol; plant bugs (Miridae) often lose their legs; and Lepidoptera lose their scales. High concentrations of ethanol has been claimed to keep the wings from twisting/folding, hairs from matting, soft organs from shrivelling and to speed up relaxing. Beware, specimens may revive if removed from the killing jar too soon. Use glass container (solvent, eats plastic).

Isopropyl Alcohol (Rubbing Alcohol, Isopropanol)

Isopropyl Alcohol (IPA) is a common alternative to Ethanol but fades some pigment-based colours, especially reds and greens; high evaporation rate, so not well suited for traps that are unattended for long periods. Can also be used in ultrasonic bath to clean specimen. Used to rinse after water bath for faster drying.

Ethylene Glycol, Propylene Glycol (Car Antifreeze)

Easily sourced, low cost killing agent and preservative. Some glycols are hygroscopic (absorbs moisture) and therefore may 'dry out' specimens (ie Propylene glycol). Use glass container (solvent, eats some plastics).

Chloroform, Ether, Carbon Tetrachloride

Used in killing jar to kill insects. Some of these chemicals harden muscles to such an extent that the specimens are brittle and seemingly impervious to the subsequent humidity of the relaxing chamber.

Sodium Cyanide, Potassium Cyanide

Cyanides are dangerous to use and should be used only by trained workers. Used in fumigation chamber to kill insects. But can also be obtained cheaply using the method used by Victorian entomologists by crushing common laurel leaves (Prunus laurocerasus) - bruise the leaves by putting them in a sock and thock them with hammer. Insects killed with cyanide usually can be relaxed very easily and successfully. Cyanide may change the colour of some bees and wasps.

Ammonium Carbonate

Solid form killing agent - alternative to liquid killing agents. The powder is not poisonous or flammable, but can be irritating to the lungs and corrosive to mucous membranes.

Barber's Fluid, Gin

Used in single drops to relax individual anatomy parts such as legs, antennae etc. Barber's Fluid is ethanol / acetone / ethyl acetate and water - used to contain Benzene but that gives you cancer.

Acetic Acid (Pickling Vinegar)

Neat Acetic Acid at 10% is used in airtight container to relax insects. Pickling vinegar is 5% acetic acid. A more pleasant odour than many relaxing fluids. Insects can be kept for a very long time relaxing in acid without deterioration.

Hydrochloric Acid

Hydrochloric acid (HCL) is used in the relaxing process to dissolve pepsin which needs a low pH value to become activated (1.5-2)

Cellosolve (2-Ethoxyethanol, Ethylene Glycol Ethyl Ether)

Soak 1-48hrs to remove moisture depending on size and construction type of specimen. Brand name used by Union Carbide to market ethyl and methyl cellosolves. Does not excessively harden specimens but is highly volatile.

Xylene or Histo-Clear

1hr - removes Cellosolve. Or used to dehydrate specimens by placing them for at least 5 minutes each in 70%, 90%, 99% alcohol and finally Xylene. If dehydration is incomplete small (especially slide-mounted) specimen can become clouded in the mountant. If specimens are in 80%-90% alcohol, they can be placed in Cellosolve (ethylene glycol mono ethyl ether) without having to use absolute alcohol and Xylene.

Naphthalene, Phenol, Chlorocresol

Used when relaxing dead insects to prevent mould.

Gasoline, Toluene, Xylene

Degreasing agents to remove fats (lipids). 1hr soak can restore greasy moth wing to original condition.

Warm Soapy Water

Used as bath to re hydrate doli eyes. Add a few drops of dishwasher liquid.

Absolute Alcohol

Pure ethyl alcohol with less than 1% water is expensive. Denatured might be cheaper but the added ingredients may make it not be effective. Squirt over wet specimens to speed up drying (azeotrope).

Water

Can be used in its own for relaxing insects, but if specimens require more than a day or two consider adding Chlorocresol, phenol, or naphthalene to prevent mould.

Hot Water

Used for larvae - no discoloration as with alcohol, and leaves larvae 'inflated' making the study of setal patterns more convenient. Surfactants in 'soapy water,' as is commonly used in pan traps, break the surface tension of the water causing insects/spiders to drown. Absorption of water often results in distended organs, however.

Paradichlorobenze (Moth Balls)

Kills dermestids (which destroy preserved specimens), but can promote grease so you may need to degrease. Also prevents mould.

Methanol

Lens cleaner. Longer chain alcohols have a higher tendency to eat plastics due their lower polarity so methanol is the best choice, if available. Typical solvents in commercial lens cleaners are acetone, methanol, and isopropyl alcohol (Isopropanol). Don't ever use pure acetone on plastic lenses. Blow, brush, wipe, and use the minimum amount of liquid, wick up any excess.

Triethylamine

Active ingredient in flynap, a commercial product for anaesthetizing drosophila. Flynap is 50% Triethylamine, 25% Ethanol % 25% Fragrances.

WD40

Killing agent and insect repellant when out in the field near mosquitoes.

Pepsin

Active enzyme in stomach acid used for relaxing very stiff specimens where the set muscles have become too hard to be relaxed with Acetic Acid.

Ammonia, Borax, Decon90

Used in taxidermy to re hydrate or prevent dehydration; 10% ammonia on dehydrated beetle eyes will bring some colour back; borax powder solution used in fish taxidermy, a very challenging craft that would appear to resemble the challenge of insect eye dehydration prevention.

Comments (9)

Article: Chemicals
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Max Rockbin says...
A note on matting: I asked on the Reddit What's This Bug community about how to avoid matting with wet insects (after one guy complained it made a bee hard to ID). They pointed me to Sam Droge at the USGS bee survey. He has posted videos on youtube as well as slide shows showing how to clean and dry bees specifically to avoid matted hair. He emphasizes thorough cleaning and either a paper towel or blow dryer technique he describes in slide shows here: http://www.slideshare.net/sdroege/presentations and on youtube here:
https://www.youtube.com/user/swdroege/videos
1st April 2015 3:05am
Johan says...
Hi Max - I've had several discussions with Sam about his autobeedryer - but this device is more designed to make his bees fluffy rather than for the short matted hair. Matted hair tends to have some sort of body grease/fats on it which binds them together and getting rid of this is problematic. Various chemicals have been tried such as Toluene to dissolve this and other degreasing agents but as yet my queries with all sorts of people have sadly still not found a good way to deal with this =(
1st April 2015 8:39am
Harold Gough says...
This may help when small insects, e.g. chalcid wasps, need to be mounted (on card or card points) for study or for photography. The problem is that the surface tension of the liquid tends to fold the wings and they will dry folded, unless suitable action is taken. I devised the following method in the 1970s: Obtain some absorbent paper. (I used standard laboratory filter paper). Place the wet insect on the paper and manipulate it with a very fime paint brush. Turn it on its back and spread out the wings, while they are still moist, so that they are flat, held against the paper by surface tension. Then let the insect dry out, which will happen with the wings held flat. Then lift the insect off the paper and mount it, as required.
1st December 2013 2:28pm
Harold Gough says...
Where alcohol solutions are a suitable preservative, those containing 5% glycerol are more likely to retain some flexibility in the appendages of insects stored in the liquid.
1st December 2013 2:11pm
Mike Adams says...
I am playing with using carbon dioxide. It is widely used for knocking out fruit flies in genetics labs, and should work with most insects. An advantage is that it does not kill the specimen, but arranging may be a problem.
27th November 2013 4:44pm
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