Insecticides Repellents and Poisons

Insecticides, repellants and poisons

Let’s start with basic safety rules about handling and storing insecticides!

Don’t ever store in drink bottles or food containers as some doofus may drink it by mistake.
It happens so commonly that in most places it is actually illegal and considered negligence. As in “negligent homicide”, something well worth avoiding…

A much safer option is old bleach, fuel or solvent bottles with a child safety lid, never soft drink, milk bottles, or jam jars. You can buy childproof bottles online for very little money. I use amber glass spray bottles and even when empty I keep them all securely locked inside an old steel ammunition crate.

Label them clearly using a method that is easily understood and can not be removed.
Kids can’t read, lazy drunk or stupid folks just won’t, and not everyone speaks your language so adding a skull and crossbones or scary image is a very good idea too. Keep them locked up out of reach of children and pets. Even if you trust them, just pretend you don’t and keep them locked up out of reach anyway. After all, the neighbours lost dog, their handicapped cousin or someone suffering from a mental illness could come over when you are not even home, entering without your knowledge, let alone permission. If they die or are injured because of your irresponsibility, then that will cause a fair bit of drama to your day to day life.
I personally love my life so I take it all very very seriously…

Never use them on food crops that you will be eating in the near future!
They are designed to kill critters, don’t let them kill you too! Cooking fumes from toxic insecticidal poisons are offensive and DANGEROUS! By cooking them all your are doing is breaking them down into smaller pieces and dissolving them into the solution. Some volatile chemical components can be evaporated and rise up with the steam vapours, which has the potential to poison you and anyone else nearby.

You are not making soup, you are making INSECT POISON!
The indoors kitchen of your one bedroom apartment is NOT a safe place to be messing around with any of this stuff.
I use our outside wood fired barbeque pit. A very affordable and simple option for folks in the suburbs are the mini camping gas burners just sitting supervised in the middle of your driveway or lawn.
These are a very cheap and easy solution costing only ~$20.00 each and you can get them from every camping, fishing, hardware, and even most supermarkets these days. Each can of disposable butane gas is ~$3 each and a single can will easily boil up 20lts of spray. That’s more than I normally use in a whole year.

Only make small batches.
Make enough to use for a specific job, then dispose of any excess safely.
You physically can’t, accidentally poison someone then. Plant-based insecticides often break down very quickly when exposed to air and sunlight.  When you first make a batch potency and effectiveness is very high but that effectiveness drops over time. Plus you just wiped out your insect issue, so there is no need to have more spray, at least not in the near future.

Handle toxic plant poisons as if they were TOXIC POISONS!
Just because it is a plant and “natural”, does not mean it is safe. When harvesting any part of these plants, in any quantities, it is a good idea to protect your skin from contact. Wearing gloves, long sleeved shirts, even chucking on a mask are all good ideas, and I always dump my clothes and jump straight in a shower when I’m finished just to be on the safe side. Sap or even just build up of volatile oils from cutting and bundling the plants can make you itchy, burn the skin, or give you a rash.
Overexposure can also cause you to suddenly become sensitive to them, whereas in the past they didn’t worry you, so for that reason alone it’s always good to be over-cautious.

The easiest way to deal with a problem is to completely avoid it from the start.

The last rule is to always assume everyone is stupid, including yourself!
If you just assume you and everyone else is a moron, and plan for super statistically unlikely moronic situations that should never really ever really happen, then you remove all ability for things to go wrong. As awesome as I am, I do really bafflingly stupid stuff all the time…
No doubt you do too, as does your Mrs, your neighbours, kids, pets, everyone on the planet. Plan for this, not for common sense, as sometimes folks just don’t have any.

Insecticidal plants.
The basic recipe at the bottom can be used interchangeably with most plant species.
Your only goal should be to kill disable or remove the insect species that is overpopulated and causing you problems to your ecosystem, without harming anything else. Depending on the plant and the insect pest this can by many different mechanisms or modes of action including but not limited to the following.

  • Damaging or interfering with the central nervous system preventing movement.
  • Turning off the signal to feed, breed or hide from predators.
  • Removing the ability of the species to pupate or develop further, like grasshopper nymph to adult, lawn grub to beetle, or caterpillar to moth or butterfly.
  • Destroying the mouth parts, the gut or digestive tract.
  • Masking the taste or smell or food plants, making the pest think it is no longer edible.

Very basic insecticide recipe.


  • 1x large pot or pressure cooker that will only ever be used for making insecticides.
  • 1x large nylon nut milk, honey, or wine filter bag that will only ever be used for making insecticides.
  • 1x heavy flat object, piece of steel, or ceramic dinner plate that fits inside the pot to weigh down your herbs. It will only ever be used for making insecticides too.
  • 1x pot half full of very tightly packed insecticidal herbs of your choice, all cut into manageable pieces.


  1. Take your pot half full of herbs and pour them into the nylon filter bag.
  2. Crush and scrunch them right into the bottom of the bag, twisting it up as much as possible to remove air spaces.
  3. Tie the drawstring of the bag shut and place it back inside the now-empty pot or pressure cooker.
  4. Lay the excess twisted bag and the drawstring neatly and then place your weight top.
  5. If using a pressure cooker make sure you do not overfill it and that the pressure release mechanism is clear of all obstruction, even when it moves during cooking. Don’t blow yourself up!
  6. While leaning on the weight to push the herbs down, slowly fill the pot with water just until the herbs are barely covered.
  7. If using a pot bring it to the boil, then immediately turn it down to a slow simmer until the herbs have oxidised gone a dark colour, and collapsed released their oils. This takes about an hour.
    If using a pressure cooker just crank it up to max for 15minutes or so then turn it off and leave it to finish cooking and cool down for about an hour.
  8. When cooled down to room temperature remove the nylon filter bag and tie it suspended above your pot so it drips all its goodies out.  I just hang it off a tree branch or the fence with the pot sitting underneath it. Keep it supervised the whole time so no kids or critters can get at it!
  9. Dump or bury the fibrous pulp and you’re done.

Now you can dilute the poison juice to a nice tea colour and spray it directly on the critters causing you dramas. One part poison juice to four or five parts water is normally pretty spot on. You can add a little vegetable oil, compost water, worm wee, fish or seaweed emulsion, or even dishwashing detergent to help it stick to hairy or shiny insects and leaves but it really is not needed.

Always mix it up really well before using and only spray in the early morning or late afternoon as it lowers the chances of the volatile oils burning your plants.  It also lowers the chances of you killing the good guys like spiders, praying mantis, bees, wasps, etc. Predatory insects do a way better job at controlling the overpopulation of insects long term than any insecticide will so be sure to never hurt those guys.

The only insecticides we use are made from the plants we grow and we don’t really even bother doing that very often.
With the diversity of species we have here now we have attracted a wide range of predators, and with everything in balance as an ecosystem of sorts, minor insect attack just isn’t an issue any more?
As soon as something gets to be unbalanced and in high numbers, something else soon comes along to control the numbers for me. Nature hates waste.

An incomplete list of insecticidal herbs and plants.

Chillies~Capsicum species
The fruit contains capsaicinoids like capsaicin, dihydrocapsaicin, nordihydrocapsaicin, homocapsaicin, homodihydrocapsaicin, nonivamide and other related chemicals. These are powerful caustic irritants, naturally bound to sticky oils within the fruit of the plant. They are long lasting, and very hard to remove, preventing all but the keenest of critters. The fruit being edible makes their use on food crops a very convenient option.

The leaves are potentially very toxic and should never ever be eaten. There are a couple of varieties that have “edible” leaves that were eaten in small amounts historically.  But in my opinion, the leaves of chillies should not ever be used as food due to the fact they are not bred or selected for taste, and definitely not for safety. They are only selected for fruit, shape, colour, yield and size, and the leaves could have any concentration of nasties hiding in them.

Capsicum species are all in the nightshade family Solanaceae. The leaves contain widely varying amounts of steroids and glycoalkaloidal poisons like solanine, solandine, nicotine, along with various other very toxic alkaloids. This is why they are only ever eaten by insects long after all the better tasting less toxic stuff is gone.

Blending the leaves and applying as a spray will make a very very effective insect repellent, as well as killing pretty much everything it touches. It is important to consider spray made from the leaves to be very dangerous and it should be handled with great care. Unlike the fruit, it is never a good idea to apply it to food crops that will be eaten anytime in the near future. If you handle it or ingest it you may experience gastrointestinal and neurological disorders which can include nausea, stomach cramps, diarrhea, vomiting, cardiac dysrhythmia, nightmares, headache, dizziness, itching, eczema, thyroid problems, inflammation, pain and even death. The fruit is relatively safe but the leaves can be very very dangerous, especially when concentrated, and they need to be taken very seriously!

Marigold, but Tagetes minuta ONLY!
This one really gets me fired up!
I understand folks hear something cool and take it as fact repeating it. The thing is if you then try it and it’s a dismal failure, then you should then also change your opinion or at least do extensive further research. Especially if you are in a place of authority charging folks big money for your expertise like those organic gardening and permaculture garden gurus and advisers that seem to proliferate social media these days.
Likewise, if you have a large and loyal audience like the TV and Magazine gardening celebrities do, then you should do your due diligence to make sure the information you provide your massive audience is as accurate as is possible.

It is a fact that multiple studies have shown some Marigold species to very very reliable insecticides against nematodes and leaf eating insects.  They also have a strong repellant action and they can even prevent seed germination of some weeds when grown together in some crops.
All true.

The thing is, it isn’t the bloody garden centre ornamental marigold!!!
Those are most often Tagetes patula, Tagetes erecta or hybrids of the two. Those guys are very pretty, and like most marigolds they are edible for people. They are also eaten by pretty much everything with a mouth as they have absolutely bugger all insecticidal chemicals.  You might as well just plant another tomato…
The real insecticidal Marigold is Tagetes minuta.
It is also called Huacatay or Stinking Roger, and it smells very strongly due to the huge amount of oils and insecticidal chemicals.

It looks completely different from every ornamental marigold you have ever seen, and it is not even normally available for sale to the public as most folks only know it as a weed here in Australia. It grows 2 or 3meters straight up and has tiny boring flowers of only a couple millimetres across. From a distance it kind of looks like Cannabis~Marijuana, if you really squint…
It is impossible to get confused about which marigold is which, and it absolutely disgusts me when I see “experts” cashing in by misinforming the public to promote their sponsor’s ornamental man-made hybrids as truly insecticidal species.

They don’t lie when they say “Marigold can do blah blah blah”, but it definitely isn’t very bloody honest of them. If you want pretty flowers then any old Tagetes species will do, they all look quite good. If you want insect killing and companion planting that actually works, as proven time and time again by scientific studies, then Tagetes minuta is the only species you should bother with. All the rest are just a waste of time and money. The part used for making spray is all the above ground parts and the very start of flowering is the most potent time to harvest.

Epazote~Dysphania ambrosioides~Chenopodium ambrosioides
This species has a million common names and for a huge part of human history, it was one of if not the main insecticide and wormer used by man to protect ourselves and our animals from worms and parasites. It also very effective at killing insects and preventing crops from attack. It contains very high levels of Ascaridole in its oil(up to 70%!) as well as limonene, p cymene and small amounts of numerous other monoterpenes and monoterpene derivatives like alphapinene, mycene, terpinene, thymol, camphor and trans isocarveol.

In small sensible amounts, it is used as a food spice and because of its depressant action on the gut it prevents wind. It is often used in bean and lentil dishes for this reason and it really makes them taste great.
In large amounts, it is very toxic to pretty much everything, especially insects, nematodes and worms.

Back in the day when “Oil of chenopodium” was commonly available in a super concentrated form, there were even occasional suicides and accidental deaths from overdosing with it. The part used is everything above the ground. The seeds and flower heads are the most potent as they contain the most oil.

Eggplant, Tomatoes, Potatoes and Solanum species
These guys are all in the nightshade family Solanaceae.
Their leaves contain widely varying amounts of steroids and glycoalkaloidal poisons like solanine, tomatine, solandine, nicotine, along with various other very toxic alkaloids. This is why they are hardly ever eaten by insects and when it happens it’s generally long after all the better tasting less toxic stuff is gone. Blending the leaves and applying as a spray makes a very effective insect repellent. It will also kill pretty every insect it comes in contact with.

It is important to consider spray made from the leaves of all Solanum species to be very dangerous and they should be handled with great care. Despite often having edible and delicious fruit, it is never a good idea to apply a spray made from the leaves it to food crops that will be eaten anytime in the near future because of this toxicity. The liquid is easily absorbed through the skin and if you handle it or ingest it you may experience gastrointestinal and neurological disorders which can include nausea, stomach cramps, diarrhea, vomiting, cardiac dysrhythmia, nightmares, headache, dizziness, itching, eczema, thyroid problems, inflammation, pain and even death.

The fruit is normally relatively safe but the leaves can be very very dangerous, especially when concentrated into a liquid. For this reason, they need to be taken very seriously!

Garlic as an insecticide in its own right.
This is mostly myth or misunderstanding but it does have the potential to cause toxicity, that bit is true. It also has a very strong repellant action because of the sulphurous chemicals it contains. But, the effective dose rate to cause actual toxicity in most insects is massive. Because the bit you want is tightly bound to the oil, the amount of oil needed to kill the critters would smother the plant, reliably killing it too. This smothering action would kill critters faster than the actual toxic action would.

Just because you add a couple of cloves to your mix and it works good or better is not because the garlic is super toxic.
It just works better because when the garlic oils are emulsified and applied they become sticky when they dry. Vegetable oil, compost water, worm wee, fish or seaweed emulsion, or detergent will all have a similar effect despite most of them being chemically pretty harmless to insects. They aid attachment to hairy or shiny smooth surfaces, and because of this, it helps the real active ingredients and irritant chemicals to do their job better. In most recipes that’s the chemicals found in the chilli plants.

Jicama~Pachyrhizus erosus
Mostly know for the huge deliciously crunchy roots they produce, it really surprises folks to discover these guys have very toxic leaves, stems, flowers and especially seeds. They are jam packed with Rotenone.
Commercial “Derris dust” or “Tomato dust” is also loaded with the stuff and rotenone is a toxic substance that reliably kills insects and just as reliably kills fish. At the same time it is destroyed by heat and light so it must be used as a powder or slurry and never heated or boiled.


  1. Harvest leaf stem flowers and stems and dry them in the shade.
  2. Grind it all up and dust it onto the affected plants.

Melia australis~Native neem~White cedar.
The attractive looking very poisonous yellow berries are insecticidal napalm when made into a spray. It is not something you would ever use on a food crop!

With these guys, it’s also very important to keep them out of the heat and light as much as possible because the neurotoxic diuretic poison Azadirachtin is destroyed by exposure to sunlight. That active ingredient is the same found in all the Neem based commercial products.


  1. Add 1cup of methylated spirits, strong moonshine or vodka to 1cup of whole fresh picked berries and leave them in the dark for 1-4weeks until the liquid goes bright yellow. The stronger the solvent the quicker this happens.
  2. Pour this liquid off and set it aside again in the dark.
  3. Add 1 cup of water to the container with the berries and shake the crap out of it here and there over a couple of days until that water goes very dark grey and cloudy.
  4. Strain the dark grey liquid, and add it to the bright yellow liquid. Like magic, it goes brilliant white and it is now ready to use.

This stuff is truly toxic and it should NEVER be used on food crops.
Imagine its a can of fly or cockroach spray. The solvent content will burn the leaves of plants and damage painted surfaces and when you consider that studies show 6-8 whole berries is enough to kill a full grown man, a concentrated spray like this is not something you want to mess around with…
It’s perfect for wasps nests or meat ants nests that are in hard to get places and resistant to most other plant based poisons.

Keep in mind those guys help actively protect your garden from insect pests so if they are not directly a serious risk to your safety you should really just consider them cranky neighbours and just leave them alone.