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!

An early infestation of Oleander 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!

    • 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.

    • 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…

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