PESTICIDE RECIPE: The Best Bug-Killing Mix for Mites, Mealybugs, Aphids, and Thrips (Works well for orchids & house plants)

In Orchid Tips & Care
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I don’t like using systemic pesticides – they are not easily available for purchase in Canada and they can generally be pretty toxic to insects, pets and people. To be transparent, I have in select situations, used imidacloprid for particularly infested plants. If you are going to opt for systemics rather than less toxic options, select something that isn’t a spray application (because it’ll increase your chances of inhaling it).

The following non-systemic pesticide is a surface application and it works well for application on a few plants; it becomes more difficult to broadly treat large collections (because all it takes is one pest to survive to restart the cycle). So start early and do your best to eradicate pests from the start AND consider applying this application to new plants you bring into your home.

It works because it smothers the insect pests—but in order for it to be effective, it needs to coat the insect. It also means you need to repeat application a few weeks in a row in order to catch any newly-emerging nymphs from eggs.

Kill Spider Mites, False/Red Mites, Mealybugs, Aphids, and Thrips

Ingredients for the Best Bug for Killing Pesticide

  • 1 Cup of Water
  • 1/2 tsp – Dr. Bronner’s Peppermint Soap – after hearing the value of this from a few sites and from Glen Decker from Piping Rock Orchids, I started using this and love it.
    • Substitution soap: 5 drops of Blue Dawn Dish Soap; not sure why the blue version is specifically called for, but it appears that everyone on the web says THAT is the one that works best (and it worked for me, so I’m not arguing it).
  • 25-40 drops of mineral oil – I have used baby oil in a pinch.
  • Optional: Some people use 1/2 ratio of isopropyl alcohol to 1/2 water.
    *I don’t but I have used straight ethanol rubbing alcohol for spidermites and mealybugs in addition to this above recipe. In that case, I’ll apply the rubbing alcohol; wait 15 mins and then apply the oil-soap mix.

Added Oomf / Additional Bug-Killing Power

More Oils! You can use a combination of these, or all of them. Your goal is around 25-50 drops total (mineral oil AND whatever substitutes) per cup of water.

  • Neem Oil is a good choice (10-20 drops)
    Often available at healthfood stores in the “pills + skin section”; coldpressed is what you want and it’s a solid at room temp, so you’ll need to heat it up before adding it to your soap/water mix. It affects the growth and feeding cycle of insects, so it’s a really good choice.
  • Cinnamon oil / extract (10-20 drops)
    Stinks—makes your whole house smell like cinnamon (which sounds nicer in theory than it does in practice)…but it does seem to work well.
  • Eucalyptus oil / extract (10-20 drops)

Directions for Applying this Home-Made Pesticide to Infested Plants

In a spray bottle mix the above ingredients. I ensure the first 20% is warm water, then I shake it mixing up all the oils, then I’ll add the rest of the cooler water to top-up the spray bottle. Shake it up, mix the soap and ingredients around before each use, then generously spray the plant. Get the tops of the leaves, the bottom of the leaves, and the stalk/stem. Also coat the mites, aphids, thrips, mealybugs or whatever bug you’re trying to kill. Soak the top and bottom sides of all the leaves (it’s okay if it gets into the substrate/soil). Let it sit for about 5–10 mins. Spray again liberally; wait another 5 mins then take them to the shower (or sink) and spray all the leaves with clean water; let the water run through the potting mix for a while too to rinse out any soap.

Tips for Mealybugs & Thrips (hard to kill bugs):

If you really want to get rid of pests on a plant, repot it the first time you do this application. Spray the leaves, the stem, AND the roots…nuke the plant with the spray. I have eradicated spidermites and false mites with a single application by doing this.

Tip for Spider mites (the kind that make webs):

Use a really fine atomizer spray bottle and just make a nice clouding mist around the plant from top to bottom. The webs will grab the droplets and the spidermites are hooped b/c they cant walk around without getting stuck in oil. I don’t even drench plants that have these, I just give it a good and even misting spray a couple days in the week, followed by a shower at the end of the week and the spider mites are gone for another year.

Tip for False/Red mites (the kind that don’t make webs):

These things are a pain and will be all over the plant including on the roots and in the pot. Make sure you fully drench the plant if you have false spider mites…for orchids like phals and jewel orchids, it’s a good idea to repot them and spray the roots. If you’re not going to repot…then run that mix through the potting media a couple times so that it kills any on the roots or in the media.

Caution: Test this home-made bug spray first

Before you go spraying ALL of your plants with this mix, you may want to test it on your plants. Also, know this: orchid buds and blooms do not do well with alcohol or soap on them. I lost a giant spike on my Phal. Malibu Madonna that had over 20 flowers on it when I sprayed—all of the flowers: DEAD.

Why does this non-toxic mite, mealybug, thrips and aphid killer work?

The soap reduces the surface tension of the water and allows the oil to mix. The soap also has that surface-tension changing property on the bug’s waxy outside layer…so insects that can normally repel, now can’t. The ratio of water to oil helps distribute/dilute the oil so you’re not coating your plant in a thick layer of oil. The diluted oil is enough to coat the insect and they suffocate. In the cases where a bug is able to avoid suffocation by the mineral oil, the inclusion of other oils like neem, cinnamon, or eucalyptus make the plant surface less ideal for the bug. Neem stops them from feeding so it’s the best. Cinnamon burns my mouth…so I assume it does the same to the bugs. And Eucalyptus is likely toxic to many bugs…so it just makes sense.

Anyways, the point is, this mix suffocates and drowns your bugs.