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.

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

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 they’ve completely engulfed you milkweed, I would suggest doing nothing and learning your lesson for next season: start your aphid battle early to avoid Gardageddon!

You could apply a professional grade pesticide like malathion, but there’s a higher likelihood 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.

  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…

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