How To Control Aphids On Milkweed Plants

7 Ideas for Keeping Milkweed Aphid-free

7 Ways to Stop Aphids from taking over your Milkweed Plants

One problem that plagues almost all gardeners across North America is the relentless attack of oleander aphids. They suck the life from milkweed like little orange vampires.

The degree to which their infestations effect plant health is debatable, but the ugliness they unleash upon your butterfly garden is not!

Aphids on Common Milkweed
A Common Pest

In 2011, they showed up in droves on our tropical milkweed. I cringed every time I walked by those plants and wondered if I should consider other milkweed varieties to cut down their numbers. A couple gardeners assured me the milkweed would be OK. Miraculously, I even found two 5th instar caterpillars crawling over the orange-covered leaves!

However, I believe the seeds I collected that season gave me a better indicator of milkweed health…only 20% of my seeds sprouted the next season! Every other year without heavy aphid infestations, my seed viability has been at least 90%.

Little did I realize, I could have stopped this infestation from getting so out of control. Now that I know how to better control aphids, I’m here to help you avoid my aphid-blanketed milkweed debacle of 2011.

Of all the questions I receive about butterfly gardening, “how can I control aphids on my milkweed?” is probably the most frequent. A good idea for all gardeners is to check your plants regularly. In the following photo, you might see two harmless aphids sitting below tropical milkweed flowers…

Two aphids looking innocent below tropical milkweed flowers
Aphids In Bloom

…but I see the potential beginnings of an aphid army!

Here’s are some tips to keep that army from ever forming, so you can save your precious milkweed plants:

Before you try any of these methods, rescue any monarch eggs or caterpillars from harms way and relocate to other milkweed, or try raising monarch butterflies inside:

1. RUB THEM OUT: some people simply get rid of aphids by rubbing them off with their fingers and thumbs . This can be effective when the numbers are low if you’re not afraid to get your hands (or gloves) dirty.

2. HOSE THEM DOWN: a steady stream of water on the aphids can also displace them. You’ll need to hold the milkweed plant with your other hand to avoid stem breakage. Using a spray bottle on stream is also effective.

3. ALCOHOL OVERDOSE: This was reported in the LA Times as the secret to killing milkweed aphids and not monarch eggs

Please note that if isopropyl alcohol is applied directly to monarch eggs or caterpillars it will kill them.

4. WASH THEIR MOUTHS OUT: a little soap never hurt anybody, but it can kill those pesky aphids. There are many homemade “recipes” floating over the internet. Obtaining information from credible .edu sites can help to avoid creating dangerous concoctions that harm plants or surrounding wildlife: Aphid Control: Soaps and Detergents

5. CUT IT OUT: if you don’t catch the aphids right away, you can still avoid harsh chemical solutions by cutting off plant stems with the heaviest infestations (and using #2 , #3, or #4 for less infested areas). Make sure to discard the cuttings far away from the garden to avoid a touching aphid-family reunion. I suggest using a yard waste can if you have one.

Still have aphids? You have a couple options left to regain aphid control. Unfortunately these options are unpredicatable and can have unintended  consequences…

Ladybugs can help control aphids on milkweed plants
Everything In Moderation

6. WHO’S BUGGING WHO NOW?!: Introducing beneficial insects to eat the aphids sounds like a great natural solution, but beneficial bugs like ladybugs and mantids also feed on monarch eggs and larvae. There are already enough monarch predators in your garden…what will happen if you unleash thousands more?

7. WORLD WAR G(arden): If it’s come to the point where aphids have completely engulfed your milkweed, cut back all areas of moderate to heavy infestation and throw out.

Aphids lay eggs when it starts to cool, so cutting down the mating population in late summer/early fall can help you avoid an aphid Gardageddon next season!

Cut Back Aphid Infestations on milkweed each Fall if you want less aphids next spring.

You could also apply a professional grade pesticide like malathion, but it’s likely that monarchs, other wildlife, and the environment could suffer injury (or worse) from using harsh chemicals. There’s a reason most butterfly gardeners use organic pest control…it won’t kill the butterflies!

Whatever solution you choose to control aphids, remember that early intervention is your best chance for for defeating these sap sucking pests.

Have any of these techniques worked/not worked for your milkweed? Have you controlled aphids with other methods? Please comment below and help other gardeners avoid the wrath of milkweed aphids. Thank you!
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Comments

  1. John U. says

    First off, it’s GOOD to see this site on Facebook. The monarch butterfly needs our help anyway we can do it considering the low population that they had in their wintering sites in Mexico.

    I believe the MAIN thing that can help with increasing the monarch population is EDUCATION! You’d be surprised (or maybe not) at how many people do NOT KNOW that milkweed is the ONLY plant that the monarch needs to breed and survive! And, as mentioned above, when some people hear the word “weed,” that’s enough for them and they fee they have to destroy it. It wouldn’t hurt for those of us that love the monarch butterfly and want to see their population increase to “spread the word” in our local communities.

    I’m thinking of talking with local borough officials in possibly setting areas apart to grow milkweed and to encourage it’s growth in certain areas where it would not be considered a nuisance. I’d LOVE to hear your thoughts and comments on this. Thanks!

    • says

      Hello John,

      thanks for your insightful post. I also believe that education is a key factor in getting the monarch population moving in a positive direction. Getting local officials to start planting milkweed in non-nuisance areas is a great idea.

      Another idea is to educate gardeners about the different milkweed species and cultivars available. Not everyone wants a garden filled with native milkweed that can potentially be invasive with underground rhizomes and seeding. I respect that. Instead of telling people what they NEED to plant based on scientific theory, I try to explain the options along with the potential issues and benefits. I currently have 8 species of milkweed growing in our garden (both native and exotic) and they all get used by the monarchs at some point in the season. A few of these species would not be recognized by most as a “milkweed” plant.

      I think anything we can do to get more milkweed into our communities is worthy of consideration since not everyone has the same motivations for growing it.

  2. Ethel Nylund says

    I would like to know what causes the milkweed to get all sticky on the leaves. I have not gotten the first Monarch this year and I am really disappointed. Any others have this problem?

  3. Don Young says

    I’ve had more yellow aphids than ever on my tropical milkweed and they’re way out of control. I should have started hosing them off early but didn’t get around to it as I have dozens of plants in my backyard. However, I’ve also had more full-grown caterpillars on my plants than ever before. This is now late January and we’ve had temperatures in the 70s and 80s here in southern California for the past 2 months. A few days ago I found 6 or 7 Monarch caterpillars and several were almost full-grown.

    I’ve begun cutting down the plants as much as I can without disturbing the caterpillars. As soon as I see aphids on new growth I’ll be sure to hose them off.

    • says

      Hi Don, sorry to hear about your infestation…the last time we had one (in 2011) I also remember finding large caterpillars on the same milkweed. The problem with the aphids is that they hurt the milkweed. I took seeds from those plants in 2011 and the germination rate was horrible…not to mention, they make the plants look sickly and disgusting.

      In 2012/2013 I noticed more lacewings and ladybugs in our garden. They’ve taken care of the aphids since 2011…hopefully some of their predators discover your garden! Congrats on all your monarchs and good luck keeping those aphids at bay…

  4. Sarah Dalton says

    #1 is my favorite — I prefer to think of them as orange bubble wrap!!! They pop so nicely! Just don’t lick your fingers or rub your eyes…

  5. says

    Hi guys, I too am plagued with these little buggers. Pay attention to you population of aphids. if you begin to see hard brown casings in and amongst them, this is a sure sign that you have a predatory wasp that eats the aphids. I was so happy when I discovered what those brown little dots on my mw plants were!

    I still rub out and spray with water. The wasps cannot get every one of them. I also have a really healthy number of lady bugs that mate and lay eggs over and over in my garden every year. Hoverfly and green lacewings also eat the aphids. Happy Hunting!

  6. says

    I bought a pair of tweezers specifically for removing these milkweed aphids from my Narrow Leaf Milkweed plants. I pick them off a few at a time and place them in a cup of water. They are surprisingly easy to pick off the plant – they don’t make any attempt to run away. If you have only a few plants and do this a few minutes each day, you can stop the infestations from getting too serious.

  7. Jacki says

    I’m in Oklahoma and the aphids are horrible. I mix a spray bottle with a couple of teaspoons of Dawn and fill the rest with water. Every morning, I spray the aphids and they’re dead by afternoon.
    I do have a new problem this year though. I have what I thought was a new variety of ladybug, but noticed the new bugs were eating the leaves at a very quick rate. They’re different colors, from beige to yellow to orange. They have a roundish body, and a snout. They’re not a worm. They’re literally eating my butterfly weed like crazy. They fall off easy enough, but will climb right back up. The soap water does kill them. It’s more of a nuisance than anything, but I’m wondering if anyone knows what these new critters are. Any feedback is appreciated.

    • says

      Hi Jacki,

      glad to hear the dawn is working for you. Sounds like a quick, easy, and effective mix. The problem with spraying in the morning is that’s when monarchs usually lay their eggs…so hopefully you get them all soon so you can stop spraying.

      I’m not sure what the milkweed pest is you’re looking for, but try searching google images to see if you can figure it out:
      http://images.google.com/

      If you want to get rid of them permanently, try the old “Japanese beetle” remedy. carry around a cup/bucket of soap water and just flick them inside. You could also try planting other milkweed varieties. Milkweed diversification is a key to consistently attracting more monarchs.

    • says

      Please have a look at this website for your beetle – it might be Milkweed Leaf Beetle. I have these in SE Texas on my plants of Asclepias perennis and A. curassavica. I just pick them off, squish ‘em, and add to the soil. I have also seen them on wild plants of A. perennis. Good luck!

  8. Jacki says

    Tony, I’m in Oklahoma and this is the first year I’ve noticed the ‘tick’ looking buggers and now these beetles. My butterfly bush has two problems; yellowing leaves that are falling off and leaves that are turning purplish/black. We’ve had a lot of rain so far so I think the moisture has contributed to the yellowing of the leaves. I’ll try to figure out how to post a link when I have time to take a picture today.
    You’re full of information! Thank you for your continued feedback.

  9. Peter Hornby says

    The LA Times article you linked to in point (3) said that alcohol is lethal to monarch eggs and larvae

    • says

      Hi Peter…it is if you get it on them. Whenever your treating milkweed you should always remove any eggs or caterpillars first. After you’re done you can rinse or spray the plant with water.

  10. Shefali says

    Hello! I read that horticultural oil will work to get rid of the aphids. My concern is making sure that our caterpillars are safe and that the oil won’t harm them. Have you heard anything about this?

    Also, will the dish detergent harm the caterpillars and chrysalis? We have both on our milkweed right now so I’m hesitant to put anything on the plant right now for fear of killing both.

    Last question: We went on vacation for a week and when we came back we saw one of our chrysalis next to the milkweed pot. Is there any way to save it? Or is it dead? Any ideas on how it would have been removed from the plant? We’re so sad about it!

    TIA!

    • says

      Hi Tia,

      any potential substance like horticultural oil or insecticidal soap needs to be rinsed off before it is safe for monarch eggs and caterpillars. You can always try hanging up the chrysalis by tying dental floss around the cremaster (top black part) of the chrysalis. If it’s going to hatch, it should hatch soon. Good luck!

  11. Ginger Burns says

    Help!

    I live in coastal southern California and have had my orange flowering milkweed for 2 years. Last year I had several caterpillars that matured and became monarchs. Also had many eggs that produced caterpillars but then the babies started to disappear. This year my plants are bigger and healthy looking with many flowers but no caterpillars. My neighbor had so many that they ate her plants to the bare stems.. She brought over 5 small to medium caterpillars and put them on my plants, they too disappeared after a day or so. Two days ago she put 8 more on my plants, 2 large and a mixture of medium and small. Today the large ones were gone and I assumed they were went off to find the ‘hanging’ spot to become monarchs. I found a “dead one” on underside of a leaf and no others. Eggs have been laid over last several months but nothing hatches.

    There something wrong either with my plants or soil. I do have some assylum and weeds growing at base of plants and there is a scattering of bark covering the soil. Plants are in full sun and are lightly watered once a week. I have noticed that the leaves on my plants are narrower than my neighbors but nothing else. I do use a smattering of flower fertilizer once a year but do not use insecticides. I’ve had aphids both years but this year they disappeared quickly with no intervention on my part. Any suggestions as to what the problem could be would be welcome.

    • says

      You may be having an issue with predators. Wasps, ants, spiders, stink bugs, lizards… If you think there is an issue with your soil, check with a local university to see if they do soil testing. They can analyze your soil, then give you specific suggestions to improve the quality.

      However, since you were successful with these plants last season, predators sounds like a more likely scenario…

  12. Ginny Reeves says

    I raise monarchs and have been pretty successful here in Houston but this year the aphids on the milkweed are insatiable. The first year we were plagued by wasps that ate our cats. I cut down the low hanging fronds on our palm trees (where the wasps were keeping house) and so that problem was gone. I also built a “nursery” where I keep the cats that is bug proof. So far this year I have released 50 beautiful monarchs. My problem is keeping a good supply of milkweed and the ever present “black death” of some cats. Has anyone come up with a reason for the “black death”? Is it the soil, is it the milkweed, what the heck is causing this?

    • says

      Hi Ginny, black death is caused by the NPV virus or a bacteria. This is more likely to occur if you cage has excess condensation. In a humid region like Houston, I can imagine you have to keep a closer eye on this. If you are interested in learning about the process I use for a 95% survival rate, you might be interested in Raise the Migration 2 starting in August

  13. Jacki Snider says

    Hi Tony, I’m back with a question. I found my first Monarch cat and eggs today on my butterfly weed. I have been plagued with aphids and have been diligent to spray them nightly with a soap mixture. They’re still there and have taken over! Now that I know I have eggs and cats, is it safe to spray with my soap mixture? I’m harvesting the eggs and cats as soon as I see them (we have tachinid fly issues here), but really need to spray the aphids

    • says

      Hi Jacki, as long as the soap is thoroughly rinsed off the milkweed leaves, it shouldn’t harm your caterpillars. Milkweed diversification and having several patches spread around your yard/garden is one of the best ways to “naturally” deter them. As your garden evolves, hopefully more of the aphids predators start to patrol it. I hope you are able to rescue lots of monarchs from those flies!

      • Jacki Snider says

        Thanks Tony. We are growing and expanding our garden and hope that next year it will help considerably. We have two 5 day old cats and 10 eggs. I’m sure we have a lot more but I haven’t found them yet. It’s been raining a lot and I haven’t been able to investigate the plants.

  14. Stacey says

    I always use a fireplace lighter to sizzle aphids. I started doing this on my hibiscus years ago. If you wave the lighter back and forth quickly, it doesn’t hurt the plant. Of course, you will want to remove any eggs or cats first. Then, I spray them with water. The aphids fall off and I have made sure I haven’t started a fire.

  15. Chris says

    I just found a cluster of these pests on one of my swamp milkweed plants this past weekend. I filled up a spray bottle with water, adjusted the nozzle to stream and blasted them off the plant while gently holding it. It worked. Bye bye aphids!

  16. says

    At the risk of sounding like a contrarian, I I have confess that I never ever worry about my aphids on milkweed.

    Milkweed grows pretty rampantly. Especially the common milkweed, asclepias syriaca.

    You note that the aphids can dampen the seed production of milkweed — I have to admit I see that as sort of a system of checks and balances. Since common milkweed also spreads underground, I don’t really need more seeds. In fact, this plant can sometimes be a real thug and will take over an entire landscape/garden.

    It is such a valuable plant to monarchs, that I prize it regardless. But I don’t mind if there are fewer seeds. I grow other things for other kinds of wildlife, so I don’t want to become a milkweed seed factory.

    Soaps and oils can harm the monarchs, and I also kind of trust the ecosystem to do its thing with this one.

    So I just leave the aphids and consider them part of the color of my garden.

    Most years I have had many many monarch caterpillars. Last year was a bad year region-wide — monarch numbers were down everywhere. And interestingly, I didn’t have many aphids last year or monarchs. But when the monarchs are good and the numbers are high, they do not seem to be bothered by the aphids.

    I suspect that there’s a relationship going on with the aphids, monarch caterpillars and the plants that may actually be productive or beneficial. If I find some data on that I’ll post it here and on my own blog. In the meantime, I do not like to treat any of my plants in any way.

    This is a great website and I love to see others encourage monarchs and milkweed. That is something we all should be doing! Keep up the good work.

    • says

      Hi Alison, I don’t typically worry about aphids either. We have lots of milkweed and the predators take care of most of them. But for those that have smaller butterfly gardens and a limited milkweed supply they can be an issue. I regularly get comments and emails from gardeners about how to treat them so I wrote this post so people would know their options. One thing I’ve come to understand over the past few years is that there’s not a “one-size-fits-all” solution for creating a monarch butterfly garden. I agree that treating plants with any soaps/chemicals in a butterfly garden is usually not the best idea, and should be considered as a last resort.

      BTW- aphids are typically a bigger problem with species like swamp and tropical.

  17. says

    I just checked my milkweed and found no leaves, no seeds but lots of those little orange critters all up and down the stalks…aaaargh. I just planted it this year in the hopes of growing a new habitat for the monarchs. Fortunately the little critters haven’t found the frier milkweed on the other side of the barn. I haven’t checked the plants down by the stream yet. I will definitely check earlier next year to make sure that nobody is enjoying the milkweed except the monarchs…

    • says

      Hi Virginia, aphids and monarchs can coexist on milkweed, but you’re not likely to get eggs during an aphid infestation. Catching aphids at the beginning is key to stopping them. However, sometimes predators will step in and take care of the problem for you. If you pick 1-2 plants to protect next season that’s more manageable than the whole garden. I still hope you get some monarchs this season, Tony

  18. Craig Popov says

    Hi Tony, I live in South/Mid Florida and am building a butterfly garden and am having a bit of an aphid problem and was reading your notes here and you mentioned using several cultivars of milkweeds,, SO please advise which might be the best for this area. I so far have 6 plants which are all Scarlet. Two weeks ago I had 8 cats that were doing well and I was going to take them in and the next morning- ALL GONE- maybe Blue Jays?
    Now plants are recovering but are COVERED with aphids- I ordered a small amount of lady bugs
    and that might help, but would like to get other varieties of the plants too!

    Thanks,
    Craig

    • says

      Hi Craig,

      sorry to hear about your aphids. Milkweed diversification is a good way to make sure you always have some viable milkweed for your monarchs. Check out my resource page that lists 18 different milkweed and what regions they are native to. there are also non-native varieties that can be grown across most of North America:

      18 Different Milkweed Varieties

    • says

      Hi Craig, also wanted to comment on your missing cats. There are a TON of monarch predators that seem to have adapted to the toxins in milkweed. It’s impossible to stop them all. Since only 1-5% survive outdoors, my best advice is to raise a few indoors where you can raise with over a 90% survival rate if you have a good system in place.

  19. Ginger Hand says

    Hi. I contacted you a few days ago about this pest, and find that the alcohol really works. Each day since Sunday I’ve been checking the 2 Swamp Milkweed plants that I have, and am down to just a small number each time – but they keep coming! (Maybe they don’t realize that their free happy hour is deadly!) But today I noticed a white residue on the leaves and pods that had been covered with the aphids. Could this be a fungus, or could it possibly be a result of the alcohol on them? I haven’t seen any butterfly eggs yet, but have a few monarchs that visit.

    • says

      Hi Ginger, perhaps alcohol residue left on the plants + the sun is burning the leaves and pods? Overfertilization can also cause leaves to turn white. Funguses are often caused by overwatering. Swamp usually starts to look a little worse for wear this time of year, though ours has responded well to all the rain. The best advice I can give you (without knowing for sure what the problem is) is to remove the affected leaves and pods.

  20. Miss R says

    I tried spraying my plants with DEET to possibly kill aphids and prevent further infestation. It seemed to kill some, but now especially my milkweed looks worse and downright awful. Should I just leave it alone?

    • says

      While DEET may kill aphids on your milkweed, it’s also going to kill monarch eggs and caterpillars. If you want to attract butterflies and pollinators, an “organic” approach is essential to your success. Native milkweed typically looks pretty bad by the end of the season, so your milkweed may be at the end of its growth cycle.

  21. Melanie says

    I work in landscaping at a 5-diamond resort, so of course Aphids are a big no-no. Best way I’ve gotten rid of them (along with spider mites) is to just hose them off. It is very beneficial to cut off parts of the plant that has more infestation, then you can hose off the rest. Definitely keep an eye on your plants so you can catch them early! :)

    • says

      Thanks for sharing your experience Melanie. Many times in home gardens (where you have the luxury of letting things play out a little longer) aphid predators will take care of the problem. We have been aphid-free the past few years without intervention, but have started to see a mini-infestation on our milkweed as this season nears the end. I did end up cutting back a few areas of heavier infestation, and now the ladybugs are taking care of the rest…

  22. Brett Budach says

    I think we need to make some things more clear for the readers. Someone I know just told me they interpreted the use of alcohol to mean that it was harmless to the Monarchs and only damaged the aphids. This could obviously lead to some horrendous mistakes in an aphid-infested garden. That was obviously a ridiculous mistake on their part, but it seems worth noting on this page that the LA Times article does say that it will kill the Monarchs, and must be used on a cottonball to dab only the aphids.

    • says

      Thanks for the suggestion Brett. It actually does say that alcohol is lethal to monarchs in the LA times article, but I added a block quote under #3 for clarification. Also, I use cotton swabs…it’s easier to access small spaces.

  23. Karen Murray Joss says

    I raise my cats inside a “butterfly house”. A netted place where I put my cats & plants. I have found that I must keep about 20 plants in pots covered with popup laundry hampers to use as the cats eat up what is in there enclosure. I have raised and released over 60 monarchs this year. I trim back the eaten up plants and regrow. When I find 1st or 2nd instar I use a fine artist brush to transfer them to the butterfly house.
    I also raise zebras this way as the are very slow growing and the anoles get them.
    For aphids I use a different brush to paint the aphids and then rinse with water; or just squish them. Very few butterflyies in my garden now – is it the heat? I live in SW Florida. I can keep my plants going all year.

    • says

      Hi Karen, a brush sounds like a good idea for scarping away aphids too…and easier to get in the nooks and crannies as opposed to with your fingers. Now that September is upon us, it will start to cool up north bringing more butterflies your way. Enjoy!

  24. Mitz Oates says

    I was in Wis for a week and gathered some milk weed seeds and hope they spout. When I returned to Florida I had lots of cats on my outdoor plants. I had to leave for TX the next day for 4 days and when I got back I could not find one cat…I think I have maybe one egg. What would get to the cats so quickly? Now my plants are 2 1/2 feet or so. Should I cut them down and let them start new once they go to seed?

    • says

      Hi Mitz,

      in Florida I would cut back plants one or twice a year to avoid build up of disease spores on overused plants. I would try to cut back during periods when there are typically less monarchs in your area.

      You also have more predators than the rest of us including lizards. There are many monarch predators that can wipe out your patch pretty quickly. Ants, spiders, wasps to name a few.

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