Aphid Control Using Garlic Pesticide | Green Patches - Mediterranean Gardening

Monday, June 10, 2013

Aphid Control Using Garlic Pesticide

Last week I had the unfortunate displeasure of meeting aphids for the first time in my container garden.  In hindsight I was the one who introduced them to my garden quite unknowingly.  They hitched a ride on my Hoya, and I had no idea they were there until two entire stems were completely covered in yellow.  I had noticed the yellow tinge before, but never really took any notice of it.  I foolishly thought it was how new stems looked, since the stems were a darker color than the rest of the plant, see the mistake here.  All was well until I realized, the yellow tinge was moving, and some of it had wings!

Hoya with Aphids
Aphids on Hoya

My first reaction was run for the shears; my second reaction was moving the Hoya away from the rest of the plants.  It took me a few seconds to realize that this was useless in my small yard.  If the aphids can fly, they don't have to go very far to get to another plant. My final decision was to run inside, and search the net.  The source of all wisdom, I was bound to find the answers there, and here is what I found.

To my relief, the yellow aphids were oleander aphids, which are mostly found on Oleander (no brainer that), Milkweeds and the Hoya among others.  They are bright yellow indicating high toxicity, and spiders and birds tend to stay away from them.  Luckily for me, they were not attracted to any other plants in my garden.  

Oleander aphids feed on the sap from the plant terminal.  A colony can get very big, very fast and the aphids can cause substantial damage to a plant.  Depending on the size of the colony, the plant can suffer a few stems, or it can be killed altogether.  A good indication of the damage done comes from the aphids themselves.  If they grow wings, then the colony is getting too large, and they are preparing to move on.  This could mean that there is not much left of the plant to sustain them, or that the colony was centralized in one place, and they have outgrown it.  In my case, all the aphids were congregated on two stems, and the rest of the plant was untouched.

Oleander Aphids, Aphids, Hoya
Oleander Aphids - Image Source

Now, how do I get rid of them?  In all my gardening adventures I always try to go as natural as possible.  The only store bought item in my garden is an all purpose liquid fertilizer, which I don't use very often since I made my own homemade compost.  I was lucky that I never had to deal with pests before, so I was quite unprepared for this one.  I once again turned to the net.  I found all sorts of homemade solutions for getting rid of aphids, and for various reasons I dismissed all of them but one.  Garlic.

Garlic is such an incredible plant. I have a high regard for it, and I always try to use it in my cooking.  I also found out that it makes a great natural pesticide.  It can be used against a whole list of bugs, diseases, fungi all without damaging the host plant. The plant will smell like garlic for up to a month, but it's a small price to pay. 

So here is the garlic pesticide recipe:

4 cloves garlic
1 cup of water
1 splash of olive oil (not sure what this does)

Boil the water and add the garlic. As soon as you can smell the garlic, take the water off the heat, and strain it into a spray water bottle.  Once the water has cooled down, add a splash of olive oil, give the bottle a good shake to mix it up, and you're done.  Please resist the urge to spray boiling water on the poor plant.

With my pesticide in hand I sprayed the aphids until I could no longer see any movement.  I sprayed the entire plant with garlic, and the smell was awful.  It worked beautifully, however, and I got rid of all aphids in no time at all.  

Hoya, Oleander Aphids, Garlic Pesticide
Hoya soaked in garlic pesticide

The reason this works is that aphids are soft bodied creatures, and the garlic will burn them up.  One drawback of using garlic as a pesticide is that it will kill beneficial insects and bacteria as well, so it would be best to use it in a localized area, not like I did.

There is a natural predator of the oleander aphid, and it is not the ladybird.  The braconid wasp attacks oleander aphids, and kills them in a rather gruesome manner.  I always imagine insects killing each other by eating one another, and that is somehow acceptable to my mind.  Not the wasp though, the wasp will use the aphids to inject her eggs inside them, sort of like an incubator.  The aphids will carry on with their daily life, until the eggs hatch inside them, and the wasp larvae start eating them alive.  Once the larvae turn into tiny wasps, they cut a hole through the aphid's body and come out, leaving behind an empty shell.  It's like watching a horror movie!

I think I will stick to my garlic remedy, it's better to fry them and kill them quickly.  The next day, all the aphid bodies had fallen to the ground, and no more movement could be seen.  My Hoya was pest free. I gave the stems a quick wipe, and that was the end of that.  My only concern now is that the stems where the aphids were are dark brown, and possibly dead.  I am not sure whether I should cut them off, or wait and see if they recover.  I think I will wait and see.


  1. I should try this too, though I once used a mixture of pepper and garlic and onion worked too :)

    1. Hi Tobiloba,

      Yes onion works as well as chilli! As long as it's natural and does the job I don't really mind what we use. Thanks for stopping by.

  2. I have heard that garlic repels vampires, so aphids should be no problem! Sounds like a good remedy. I think the olive oil helps the solution to stick to the plant.

    1. Hah, that's true. Someone else told the same thing, olive oil is to stick to the aphids and the plant. Thanks for stopping by.

  3. Great advice I've got the water on the boil as I write.I really don't like killing anything but when it's a pest like this I can't see any alternative. Thanks again!!

  4. oil helps the mixture cling to the plants better.

  5. I soak a cotton pad with rubbing alcohol and wipe it down the stem to remove them. Seems to work, with no ill effects.

    1. I put alcohol in a spray bottle, hang the plant in the shower, spray and in a few minutes wash/rinse the plant.

  6. Thanks everyone! Just what I needed. It's "natural or nothing" for me and I didn't want to lose my aphid-overcome plants.