Aphids and companion planting

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  • #14842


    I often hear things like "plant garlic by your roses to deter aphids" but does this actually work? And does it also work for milkweed aphids (Aphis nerii) or just the kind of aphids that go for rose bushes. When I google aphid+rose it seems that kind of aphid is Macrosiphum rosae?

    Likewise I’ve also been told sage repels aphids from celery, but when I google aphid+celery it seems that kind of aphid is Myzus persicae.

    Another suggestion is that aphids are repelled by the smell of marigolds. Which aphids? Which marigolds? (French Marigold, Tagetes patula; Mexican marigold, Tagetes erecta; English marigold, Calendula; Tree marigold, Tithonia diversifolia; Desert marigold, Baileya multiradiata; Corn marigold, Glebionis segetum; Marsh marigold, Caltha palustris)

    Others say sticky yellow traps are the way to go.

    It’s all very confusing to a novice gardener such as myself.

    Has anyone ever tested these aphid deterrents for effectiveness? Does anyone want to help test them?

    What I suggest is we do some research!

    (how did you know I was going to say that? ;->)

    If you know of any other supposed aphid repellents then please post them to this thread. For instance our aphid factsheet also mentions banana peel as at deterrent.

    Want to be a tester? The trick to research is to focus on the thing you are testing by eliminating as many variables as possible. So we need everything else to be the same, the only difference will be in the deterrents.

    So get 2 or more large pots or planter bags. I reckon PB8 would be a good size. That is 8 pints or 4.8L. But whatever you use make sure they are all identical. Buy a bag of potting mix and put the same amount of potting mix in each bag. This will make sure any differences are not due to the soil chemistry.

    Plant a couple of seeds in each container. Use the same sort of seeds for the whole set, eg all G.physocarpus, or all A.currassivca etc.

    Leave one pot with just the host plant. That will be your control. Then plant your chosen deterrents in the other ones. Label the pot carefully. A good way is to label the pots A,B,C and somewhere else record A= Tagetes patula, B=control, C=banana peel or whatever you use.

    Put them somewhere where they can be close to each other, but not too close. We don’t want the Tagetes patula or whatever in pot X to protect all the other pots as well. They should also be in similar conditions. We don’t want one in the shade and another in full sun for example. Finally whatever else you do to them, do it the same to all of them, eg the same amount of water etc.

    Then wait for the aphids to come calling. When they do resist the temptation to squash them or wash them off, just wait and see what happens. Finally you could ask a friend or neighbour who doesn’t know what you are testing to rate the plants in terms of aphid attack. Photos of each would be great too.

    Then post your results here. If we have a lot of testers we should be able to build up a pretty good picture of tried and true Aphis nerii deterrents.

Viewing 25 replies - 1 through 25 (of 43 total)
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  • #32788


    Interesting read.

    This is my first swan plant and Monarch season, just to add more info the the research, my plants have vast spearmint plants around them, chives just inches from the base of  a couple of plants and I often throw banana peal in the herb/swan plant garden. Sadly Aphids were a plague here too !

    I have since made up a spray  bottle of boiled water, dish wash detergent (tablespoon-ish) few mils of any cooking oil and I steep granulated garlic in boiling water , draining a couple of teaspoons of the liquid.

    I spray direct on to the aphids ( and anything else in the garden ) and repeat every week or so. The numbers lessen dramatically or disappear all together.

    I also sprinkle dried granulated garlic ( from bin Inn) around our vegie garden and any trouble spots, each time you water or it rains the odor of the garlic releases and sorts out the bugs. I reapply every couple of months.



    I forgot to say that I think a small hover fly type insect is also predating on the Aphis nerii.  I have taken a photo of the fly.  I will try and upload it. I havent done that before



    My observations on those horrid orange aphids in Dunedin.  Hosing no real use, have to do it every day.  Leaving it to the ladybirds only works so so, they out do the dozens of ladybirds I have in the garden.   The winter here does nothing to reduce their numbers, unlike other aphids.   Garlic spray dosn’t work very well.  Squishing the clusters round the stem does drastically reduce their numbers and the available breeding and accumulation sites, they do not seem to like  breeding on top of this black stuff.  I dont wash it off.  The couple of times the rain has done so the aphids are back again.   I have my suspicions about ants too.  The do eat the carcase remains of my squishing  but I am wondering if they are spreading them.  There has been a drastic reduction in the infestations since the nearby nasturtians got rampant.  I dont know if there is a link as it is also very hot and dry here this year and despite my assiduous watereing the aphids may be succumbing to the weather.



    Great reading about Aphidius colemani.


    I was looking to find out if A. colemani was something that ants like – I had my suspicions. I went out there this morning to find that ants are onto the mummies, i.e. they’re probably eating them! Aargh!!! What’s that saying about you try and solve a problem, and you just create MORE problems. 🙂




    Wendy – just noticed your comments. Not sure about your rhodo problem… I guess you have to just try different things to solve problems. I surely don’t want to use a product that is bad for the environment.

    I ran out of time using the garlic etc spray which seemed to be working if I used it every day, but there’s not time to do anything, so I contacted the folk at Bioforce about Aphidius colemani which I have used before with success. This is what they told me:

    Aphidius, and biological control in general, are much better at maintaining pest populations at low levels than quickly controlling large populations of pests. If you feel that the aphid population will kill your plants soon, then it is unlikely that Aphidius will be able to reduce the population quickly enough. Aphidius works well if introduced when aphid populations are small, or if released periodically as a preventative. Aphidius will take at least 2 weeks to develop inside the aphid at current temperatures before emerging as an adult and continuing the process. Aphidius is a good control measure for aphids in the genera Myzus and Aphis, but its parasitism levels are much lower in less suitable hosts.

    Are the aphids on plants that have caterpillars on them already?

    Bioforce promotes the concept of Integrated Pest Management (IPM). In some cases it may not be feasible to control the pest using biological control, for whatever reason. In that case, the judicious use of a chemical pesticide might be the best option. The pesticide Chess (pymetrozine) appears to be very benign to most organisms, including people, and could work well to quickly drop the aphid population. Its mode of action causes sucking insects like aphids and whiteflies to have a reduction in saliva production, preventing them from feeding, with the aphids subsequently dying. It has essentially no impact on our beneficial organisms, and is not known to cause mortality in chewing insects, including Lepidoptera or beetles. If your aphid population is high, it might be an idea to spray with Chess, then introduce Aphidius once the sprayed aphids have died (as the parasitism would otherwise be wasted). If you were using with your Monarchs already on the plant, then perhaps you should try a test plant or leaf.  

    If you are comfortable that the plants can survive the current aphid population for a reasonable amount of time, then I’m happy to supply the Aphidius now. We also have some ladybirds that control aphids, however they may eat monarch eggs.

    Also, as a secondary note, the plants will have Aphid mummies on the leaves, as they remain for some period after the wasp has emerged. A consideration for display plants, however they can be washed of if needed (although they do hold fast).

    I inquired about Chess but it was only available in rural retail outlets – rural as in Pukekohe, Drury, Taupaki – too far away for me. Also, the chap I spoke to about it said much the same as the Bioforce man – “much better at maintaining pest populations at low levels than quickly controlling large populations of pests”.

    So last night, I went out there and squished and high pressure water hosed the avphids I did have and knocked them back to manageable numbers, and today released the A. colemani.  Bioforce despatched them the day I paid – marvellous turnaround – and they were here the next day.

    Will keep you informed.



    re the confidor issue – I had a beautiful young rhodo so badly infected with thrips that it nearly died.  Repeated assault on the little beggars with thrips  eventually saved the plant and it is now growing well.  If I don’t use confidor, what is the alternative?



    Had an interesting experience this year. Last year my tree was ruined with aphids so when they appeared this year I squished them all  – every day or two for maybe a week I went over the tree and squished.  My population was gone and it hasn’t really come back, neither have I had them on the nearby roses, even though they were a different colour / type to the swanplant ones.



    Build up of aphids again and growing – took action a couple of days ago and now, NO APHIDS!

    So I’ve kept a record of the “secret formula”.

    I have a cheap spray bottle which I bought at a $2 shop. Almost fill it with tap water. Add 1 tsp oil (anything), 1 tsp detergent, and squeeze in the juice of 3-4 garlic cloves. Spray the plants with this and left it until the next day. Make sure you spray from more than one side (i.e. I spray from 12 o’clock {imagine you’re looking down on a clockface], give the plant more than a 1/4 turn so you’re at 4 o’clock now (or your body, move around the plant) and spray again, and then the last spray from the “other” side (8 o’clock). That way you get them from all angles.

    Next day I hosed the leaves well. Aphids like new growth so that’s where you’ll find them. More information here:


    Aphids! BE GONE!!



    Great thanks Jacqui. Sure is interesting.

    We may give the recipe a go and see what happens.

    Thanks 🙂



    No Charlotte – still no aphids, interesting eh? I just used olive oil – whatever I reached for in the pantry – no secret ingredient and definitely no recipe as such, a bit like my cooking, a bit of this a bit of that.



    Jacqui have your aphids come back on your swan plant since you used this recipe below?

    So I came indoors, got a toothbrush, some detergent, some oil and some garlic and mixed that up, brushed it on with the toothbrush. Waited ten minutes, washed it off and there are now no aphids on the property! That was 2-3 months ago and still no aphids here. Unbelievable.

    Having recorded that… it will be just my luck that I have an invasion tomorrow.

    What type of oil did you use?

    They can be pesky little blitters that’s for sure.



    I hadn’t been aware of that until recently – and see where a while ago I suggested it could be used!

    Thanks for telling us, Romi. Is any action being taken in this regard? If this is correct we should recommend that it be taken off the market. There aren’t many bees in my garden this summer at all.



    Romi Curl

    Hi there

    I am new to the site and having a look through, on the topic of aphids, saw that someone had recommended Confidor to get rid of them from Swanplants. This was an old posting, so hopefully we are all wiser since then, but I still need to say: PLEASE DON’T USE CONFIDOR AT ALL in your garden. This contains Imidicloprid, one of the Neonicotonoid group of insecticides that is known to be toxic to bees. It can disorientate them so they can’t find their way back to the hive, and it can kill them. I would like to see all of these products taken off the market. Bees, like our butterflies are precious, and their numbers are declining rapidly, here as well as overseas. Best regard, Romi







    Strange how it goes, Neil. I have seen only a couple of paper wasps over the past few days – and they seemed to be buzzing flowers.

    As far as aphids, I did have about 2 inches of them on one milkweed shoot, squished them one day, went back the next and they were back in about the same numbers. So I came indoors, got a toothbrush, some detergent, some oil and some garlic and mixed that up, brushed it on with the toothbrush. Waited ten minutes, washed it off and there are now no aphids on the property! That was 2-3 months ago and still no aphids here. Unbelievable.

    Having recorded that… it will be just my luck that I have an invasion tomorrow. 🙂

    I do have silver-eyes and fantails around, so that may be helping.



    I have had a dramatic drop in aphid populations in recent weeks, I don’t know why but suspect White Eyes are eating them as there has been a lot of white eyes frequenting the plants. As they are fairly timid I haven’t been able to observe what they doing. Does any one know of this actually happening?

    Before this occured some plants were dying from heavy infestation of aphids. I have used insecticide on my fruit trees which are close by, but was very careful and there are now thousands of cats and hundreds of butterflies so I don’t think there is a co-relation there.




    Hi there

    Here’s something that might be worth trying if you have less than 100 aphids… but remember if it was 100 when you last looked, there’s probably 105 now… and 110 next time you look.

    From a story on the Gardening Pages of the LA Times:

    “Though tedious, dabbing aphids with cotton swabs dipped in isopropyl (rubbing) alcohol is most effective. That kills them outright. Alcohol, however, also is lethal to monarch eggs and larvae, so care must be taken when dabbing.”




    According to what I’ve read, A.colemani is very good at scouting out even small colonies of aphids. The mummies don’t need sustenance, and that is how you can buy them. So yes, those old branches with mummies could be useful.

    However like ladybirds, A.colemani are better as a preventative: they can’t really keep up with a swarm of aphids popping out new aphids as fast as they can clone them.

    The length of the life-cycle of A.colemani is temperature dependant, but interestingly the mummy stage is near the end. An infected aphid can keep moving and feeding for days, so those “a few live aphids” you mentioned are probably on their way to becoming mummies as well.

    The bad news is that there are hyper-parasite wasps which prey on A.colemani! The mummy looks similar, but A.colemani leave a clean round exit hole, while the hyper-parasite leaves a messy hole. That isn’t very helpful since its a bit late once the hyper-parasite has left, and with my eyesight I don’t think I’d be able to tell the difference anyway. But either way its fatal to the aphid.



    Hi Darren – don’t know how I posted that – I started writing it, then realised I was wrong, getting my wires crossed. Didn’t realise I “sent” the post, thought I’d deleted it.

    So… here’s my next thoughts: I have these mummified aphids on dead/dying swan plant with a few live aphids as well. If I was to put this on top of the mulch in a part of the garden where there are no swan plants, I think the wasps will come out of the mummified aphids and then go in search of live aphids, won’t they?

    Question: The mummies don’t NEED any sustenance until the adult wasps come out?

    I’ll never have a garden free of aphids, pests etc, but this seems to me to be an effective way of controlling the aphids. What do you reckon?



    No worries Sally.

    Jacqui, Ladybird beetle eggs look like this:

    Aphids that have been parasitised by our friend Aphidius colemani (Viereck, 1912) look like this:



    Thanks Darren. After posting my comment above I found your other topics on aphids (including re. ants). So, sorry, I’ve really just taken up space here :). I didn’t know ants can be pillar-predator though….good to know.



    Darren – with the research you’ve been doing, can you tell me something about aphid mummies, which I know will become ladybirds. I have just cleaned up my butterfly house so have kept the aphid mummies… I wonder how long it will be before the ladybirds come out.



    Hi Sally, welcome to the forum. Ants are a predator of butterfly eggs and small caterpillars, so its best to keep on top of ant colonies anyway. But yes, ants also farm the milkweed aphids for honeydew and other nutrients. Different chemicals from the plant are also found in the honeydew depending on which bits the aphids are on, and ants prefer the colonies from the flower tips 3-4 times more than colonies from the leaf terminals (Are ant-aphid associations a tritrophic interaction? Oleander aphids and Argentine ants. C. M. Bristow. Oecologia, Volume 87, Number 4 / September, 1991 http://www.springerlink.com/content/v22m7345j61q4120 )



    Hi everyone. My first post in your Forum. Firstly Id like to say how wonderful you all are!

    Darren, have enjoyed reading through your aphid experiment. Amongst your research did you come across mention of Ants? I few years ago I read that Ants farm aphids. Given that aphid infestations seem invariably to have an energetic ant trail going to and from, there could be something in it?

    I haven’t gardened enough since reading the article to have properly tested whether getting rid of the offending ant nest actually helps but maybe?



    I agree Jane that all those have their place in a well balanced garden. Although I have used Wildflower World’s “Butterfly Garden” mix in my latest garden, I have added Borago officinalis, Phacelia tanacetifolia, Tropaeolum majus, and a few others to attract predatory insects.

    However during my literature search I had found many references that specifically stated that Coriander would repel aphids, for example



    Hi Darren,

    If you’re trying out coriander for attracting ladybirds, you may like to try other umbelliferous family members. Ammi majus member and relatives like queen annes lace, bishops flower, parsley carrot and parsnip. Their family of anthriscus, carrota, and ammi are well known for attracting beneficial insects due to their pollen. Kings seeds were selling a beneficial insect blend which included these flowers.

    Personally I have found too that the ladybirds can’t keep up with the burgeoning ahpid population rate!

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