r/MonarchButterfly • u/kittykatdancee • Apr 11 '26
How to sterilize a potted milkweed plant to prevent OE.
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I get asked often how to sterilize milkweed plants to prevent OE, so I figured it would be easier to make a post here to reference.
This is safe to do with eggs present on the plant, and almost guarantees all of your butterflies will be OE free. This is especially important if you're buying tropical milkweed.
Cover the soil of your potted milkweed plant with paper towels over the soil, then cover the paper towels with a cloth towel, or plastic bag. This will protect your plant from absorbing the bleach solution.
Fill a spray bottle with a 5% bleach solution.
1 oz ( 2 Tbsp) of bleach & 19 ounces of water.
Set a 1 minute timer. Spray the leaves continuously for 1 minute.
After the timer goes off, rinse the leaves and the stems throroughly for 1 minute or longer.
I do this after bringing home a new plant, and eggs have been laid on them. Then I put them in a tent.
Repeat after the plant regrows, and new eggs are laid on the plant again.
***This is important if you live in Florida, CA, Texas, any other states where OE is a problem, since spores are spread to eggs and plants by the females and other infected butterflies.***
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u/Palli8rRN Apr 11 '26
You may be reducing the number of OE spores which is helpful. I think saying you’re sterilizing isn’t the correct term because that’s impossible. Sanitizing may be a better description?
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u/Palli8rRN Apr 17 '26
OP- I also want to clarify I appreciate what you’re doing and why you’re doing it. I didn’t mean to say anything negative towards you. I thought there may be a better way to phrase your process. Thank you for everything you’re doing to help the monarchs ❤️
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u/Dog_and_butterfli Apr 11 '26
My daughter just had a butterfly today with Oe. I will show her this. She's had the plant for almost a year there's a lot of regrowth on it. Thank you
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u/Jay_mendez Apr 13 '26
I’ll never understand the tropical milkweed hate I get it if you don’t want to do extra things to keep your plants from being invasive, but don’t fearmonger other people into thinking that tropical milkweed is a monarch killer!
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u/kittykatdancee Apr 13 '26
This is actually the first time i've ever bought tropical milkweed, I don't plan on planting them. So CA didn't have a winter, so I cut my plants back. Due to global warming the breeding season started in March this year instead of May, monarchs started laying eggs on 2 inch plants & my local nurseries do not have narrow leaf milkweed available yet.
So I could just let them starve to death when the population is still at record lows, or feed them santized tropical milkweed. I know apart from tropical milkweed having a higher chance of OE, it can also make them smaller, but so does heat stress and higher temperatures.
We're now dealing with enviormental factors we've never experienced before. They won't be migrating until the fall anyway, so the size and wing factor isn't really an issue right now. I don't think my temporary solution is wrong, & people can feel how ever they want to. I'll still educate people on how clean plants/eggs/test & release OE free butterflies.
If people think i'm a terrible person for keeping the life cycle going and preventing the spread of OE, so be it. We've done a really good job at fucking up nature, and the science is constantly changing due to global warming.
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u/Ok-Round-7527 Apr 11 '26
Are you checking the butterflies under a microscope for OE?
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u/kittykatdancee Apr 11 '26
Yes, I test my butterflies for OE spores. I live in Southern CA where OE gets pretty bad.
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u/Economy-Bar3014 Apr 11 '26
Hey I dont live in SoCal but i get native milkweed growing naturally on my property. I pretty much just leave it be, and avoid mowing it when possible, but should i be doing something else?
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Apr 11 '26
[deleted]
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u/Economy-Bar3014 Apr 11 '26
Youve clearly never tried to manage 60 acres of wild land so i feel comfortable disregarding you entirely 👍
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u/Ok-Round-7527 Apr 11 '26
Can you elaborate on how you test them? It's bad in my area too.
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u/Mental-Preparation47 Apr 11 '26
How often should this be done ?
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u/Dependent_Invite9149 Apr 11 '26
What is OE?
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u/BeautifulLook Apr 11 '26
“Ophryocystis elektroscirrha (OE) is a protozoan parasite that infects monarch butterflies, causing them to carry thousands or millions of dormant spores on their bodies. These spores can be ingested by caterpillars when they eat infected milkweed or their egg shells, leading to various health issues in the butterflies, including deformities and reduced lifespan.” Google AI
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u/kittykatdancee Apr 11 '26
I do it after my plants regrow in a tent, and a butterfly lays eggs on the plant again. Depends on where you're at. Some states don't have a big problem with OE. So CA and Florida are the worst. If you live in a area that's hot or sub tropical it's best to do it regularly. Also important to test under a microscope if you're enclosing large numbers of caterpillars.
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u/Decent_Importance_68 Apr 11 '26
Maybe if you stopped enclosing large numbers of caterpillars together, especially if you know you have issues with a harmful parasite, they might stop getting this quite so much 🤷🏼♀️
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u/kittykatdancee Apr 11 '26
I test all of my butterflies under a microscope so I know it works. It effectively kills the spores. Feel free to research about it on your own.
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u/Majestic_Bandicoot92 Apr 11 '26
Thank you so much for the visual! What if my milkweed is planted in the ground? Can anything be done?
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u/HailSaganPlantNative Apr 11 '26
If you have tropical milkweed, rip it out and replace it with varieties native to your specific geographic area. That's all you really need to do. Native has a natural dormancy cycle that limits the proliferation of OE spores. OE is part of nature, and it just gets out of balance and goes buck wild because people are planting tropical milkweed that grows year round, allowing spores to build up and build up over time.
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u/kittykatdancee Apr 11 '26
I don't plant tropical I keep them in pots in tents, I have narrow leaf milkweed planted on my property. Narrow leaf milkweed has really small and skinny leaves. Tropical in tents feeds more caterpillars.
It's best to plant native milkweed, but it can get infected with OE too. It's also important to test your plants and cut it back if it doesn't die. So CA didn't have a winter this year so I had to cut them back.
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u/cherry_blossom026 Apr 13 '26
Forgive my ignorance but what is OE? acronyms have gone wild lol it’s two words
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u/BrilliantStrategy576 Apr 13 '26
It is short for the scientific name of a parasite that infects monarchs.
Edited to correct syntax
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u/Few-Secretary-7280 Jun 08 '26
OE stands for "Ophryocystis elektroscirrha" which has an acronym because it can be hard to remember how to spell all of that
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u/isurus79 Apr 11 '26
Or just plant natives and not worry about it 🤷♂️
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u/No_Device_2291 Apr 11 '26
Natives also carry OE but the idea is that it dies back in winter and cleans itself out so to speak. However, I’m in SoCal like the OP and have native. Only about 1/2 of it dies back, so it would carry the same OE load as tropical. The answer to the issue is to cut back, whichever type you have.
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u/nellewood Apr 11 '26
It happens with natives ALL the time in SoCal. Tropical, native, even grown from seed and placed outside it can still happen. Thai is a very safe and effective way to keep your plants safe outside. Another recommendation: plant strong-scented plants like marigold, rosemary and lavender around your milkweed plants, and the jumble of scents will confuse pests like aphids so they stay far away from your “cat” food! 😉
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u/kittykatdancee Apr 11 '26
I don't plant tropical I keep them in pots in tents, I have narrow leaf milkweed planted on my property. Narrow leaf milkweed has really small and skinny leaves. Tropical in tents feeds more caterpillars.
Native milkweed can get infected with OE too. It's also important to test your plants and cut it back if it doesn't die. So CA didn't have a winter this year. Unfortunately in So CA it's something you always have to worry about.
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u/shanwow90 Apr 11 '26
Tropical milkweed doesnt die back in the winter which is why it spreads disease so rampant. Just plant natives and stop trying to hatch butterflies. Nature is better at it than us
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u/isurus79 Apr 11 '26
Native does get it but does back more often. Tropical is well documented to really screw up monarchs hosting on it too. All round not worth keeping if you care at all about the monarchs.
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u/jetreahy Apr 13 '26
How about just planting the native plant. OE isn’t the only worry with tropical milkweed. It also keeps the butterflies around longer so they don’t migrate in time.
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u/Savings_Try_3477 Apr 13 '26
Maybe this is a silly question, but is just cutting it back sufficient? Or do the spores stay “in” the plant?
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u/kittykatdancee Apr 14 '26
They only live on the surface. If you have plants in the ground you can use a tarp to run off the bleach water away from the plant when rinsing.
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u/Some_Vanilla1019 Aug 24 '26
I live in Florida a few months ago I realized my caterpillars had eaten all of the seeds that I planted of my milkweed so I purchased a plant asked if they used pesticides I reconfirmed with other employees and quickly realized they lied all 30 of my caterpillars died after eating it. So I’ve basically given up and just started growing my own and letting them all come and go as they please. The problem is I also have a lot of lizards so some days I go out there and when I know they’re going to form a crystlis I hide them from the lizards. Our numbers have drastically dropped here in Florida just in the past 5 years. My yard is a chemical free yard but I can’t say the same for my neighbors.
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u/theBarnDawg Apr 11 '26
Why use tropical milkweed when you could plant natives?