12 Good Ideas for Keeping Milkweed Aphid-free…and 1 Bad One!
One problem that plagues almost allgardeners 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!
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 replacethe tropical milkweed 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, the seeds I collected that season gave me a better indicator of milkweed health…only 20% of thoseseeds sprouted the next season! Every other year without heavy aphid infestations, seed viability has been about90%.
Keep in mind expectant monarch mothers will also avoid laying eggs on aphid-infested milkweed leaves…and if they did, would you ever be able to find them?
Little did I realize, I could have stopped ourinfestation from getting so out of control. Over the yearsI’ve learned more about treating aphids and preventing infestations, soI’m here to help you avoid our 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. Below, you might see two harmless aphids sitting under tropical milkweed flowers…
…but I see the potential beginnings of an aphid army!
Here’s are 12tips to keep that aphid army from ever forming, so you can save your precious milkweed plantsfor monarchs:
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.
UPDATE:Community Member Joe G. says he uses a small spray bottle filled with isopropyl alcohol to spray the aphids on his plants. After about 5 seconds, he hoses the plant down with water and those pesky milkweed invaders are dead. This sounds like a great idea, but I would only recommend this for heavy infestations…don’t destroy your local ecosystem with an aphid-free garden!
4. WASH THEIR MOUTHS OUT: a little soap never hurt anybody, but it can kill those pesky aphids. Add 2 Tablespoons of dish soap to 1 gallon of water and spray the aphids directly, rinse, and repeat. Get more details here:
How to Use Dish Soap to ConquerAphids
5. BRUSH THEM ASIDE: Use a detail brush to brush them off the milkweed plants and get in those nooks and crannies without damaging the plants:
Find a Detail Brush to Sweep Away Aphids
6.GROUND THEM:Those naughty aphids need a time out, so keep them away from their favorite milkweed plants by sprinkling coffee grounds around them. There are conflicting reports as to how effective this is, but it can’t hurt to try.
7.DIVERSIFY and SCRAMBLE: This preventative measure can become very effective as your milkweed patches start to mature. Try planting several species of milkweed, and put them in several areas of your yard and garden. The aphids will likely have a favorite area and you can sacrifice one small patch to the angry aphid gods.
More milkweed varieties could attract more aphid predators too. Could it also attract more monarch predators? Yes, but that’s a good excuseto bring a few eggs/caterpillars inside to watch the amazing process of monarch metamorphosis.
Still have aphids? You have a couple options left to regain aphid control. Unfortunately, this next option option is unpredictable and could have unintended consequences…
8. WHO’S BUGGING WHO NOW?!: Introducingbeneficialinsects to eat the aphids sounds like a great natural solution, but beneficial bugs like ladybugs and mantids also feed on monarch eggs and larvae.
In some regions, parasitic wasps have been released to control unwanted pests. Unfortunately, these wasps are also targeting beneficial species, including monarchs! ?
There are already enough monarch predators in your garden…what will happen if you unleashthousandsmore?
On the other end of the spectrum, I’ve heard reports of mass ladybug releases, only to have them all leave without making a dent in the aphid population.
9. REPEL WITH PLANTS: Some plants,includingonions and marigolds, have been shown to repel aphids and naturally reduce their numbers. Planting these repellents close to milkweed can attract more butterflies whilekeeping aphid numbers down to reasonable levels.
California Butterfly Lady, Monika Moore, takes thin strips of banana peels and places them on milkweed stems near buds/blooms where aphids like to congregate…not appealing to aphids!
10. CUT IT OUT: 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. 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.
Then, try options #2 , #3, or #4 on less crowded areas so they can’t start another infestation.
It’s not fully understood if/how oleander aphids overwinter, but cutting back infested milkweed plants in late summer/early fall might help you avoid an aphid Gardageddon next season!
11. STICK ‘EM UP:this seems like a good option for indoor plants if you discover the aphids beforea serious infestation. Community member Micha B. also suggests wrapping the tape around a pencil to increase the sticky surface area:
12. SUCK THEM UP: This aphid-control strategy was recently shared with me and it eliminates the aphids without using any harsh chemicals or hurting the milkweed.
Patrick attached a micro attachment forhis full-sized vacuum cleaner, but you could also try a mini keyboard vacuum cleaner
.
How effective is this strategy? Video doesn’t lie:
13. A BAD IDEA: You could also apply a professional gradepesticide 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 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.
Info about Organic Pest Control for Other Milkweed 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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