Milkweed Diseases

Are you dealing with milkweed fungus, leaf spot, and other issues not caused by annoying milkweed pests? Then you’ve come to the right page…

Milkweed Diseases can ruin your plants and create a garden eyesore. How much these diseases affect monarch caterpillar health is still in question. Check out some ideas to treat and prevent milkweed disease and other not so fun-gus...
Photo Courtesy of David Allen Jones

Over the years, I’ve been less concerned about what’s ailing our milkweed, and more concerned about treating it early. This strategy has worked well to keep our milkweed patches healthy and ready to support monarchs.

Funguses are often the result of too much rain or watering. When leaves turn yellow, or start getting spotting/discoloration, try one or more of the following:

1. Remove sick leaves–  Whenever you come across sickly milkweed leaves, remove and discard. When it make sense, prune away entire sections of the plant. Do not compost diseased leaves/stems and risk spreading fungus spores into the soil.

2. Thin out the herd– if your milkweed plants are crowded, your milkweed patch can become a breeding ground for fungi. If you don’t have milkweed to spare, you can transplant what you remove:

How To Successfully Transplant Milkweed with Taproots

3. Water at the base of the plants– this is less necessary if your plants have good air circulation.

4. Spray spores away– spray milkweed plants and the surrounding soil with a hydrogen peroxide mix (4 parts water to 1 part peroxide) to kill fungus spores:

Click Here to Buy Hydrogen Peroxide for your Garden <<<

Hydrogen Peroxide Mix for Sick or Fungusy Plants

Find a Garden Sprayer for your Hydrogen Peroxide Mix

Hydrogen peroxide also adds more oxygen to the soil to prevent root rot. It can also prevent another common fungus that causes milkweed to wilt and die.

What can you do to stop milkweed fungus from ruining your milkweed patch? These these tried and true tips for growing healthier milkweed plants for monarchs and their caterpillar kids.

5. Replenish their milk?– for fungi similar to blackspot, try this simple rose remedy after removing the affected leaves:

Milking your Milkweed

note: If you’re spraying sickly milkweed and notice webbing on the plant, you’re probably dealing with microscopic (almost) spider mites and can check out our milkweed pests page for specific treatment options.

Milkweed Yellows Phytoplasma

This bacterial disease is spread mainly by leaf hoppers and is recognized by yellowing leaves with twisted shapes, and die back of branches. Plants affected by this should be immediately removed and discarded. If left for the leaf hoppers, they’ll quickly spread the bacteria to other plants in the vicinity.

If you’ve successfully conquered milkweed diseases by using other techniques not listed, please share your experience and help a gardener out…
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  1. Hi Tony, I live in MA and have about 9 growing cars of various ages. I’ve got them separated into three different milkweed cuttings. Yesterday they ate everything and today, I cleaned and replaced food with fresh cuttings from the same found space I’d fed them leaves from before. These cuttings aren’t a perfect looking as some of the others but I can’t identify what I’m seeing. How do I know if the cuttings are ok for these caterpillars? It’s been all day now and they’re slow to munch. After yesterday’s wild feat i expected most of these leaves to be gone by now. Should I try and find new cuttings from a different source? It looks like tiny black / brown dots all over the underside and almost like bruised or wet spots on the top side. Could I have maybe just beat them up a bit too much when I was washing them? Thanks in advance for your help!

    1. hi Caroline, sounds like it could be a fungus…if supply is low I would just offer them the best of what you have. Plant diseases shouldn’t affect caterpillars, but if you have access to healthier milkweed I would use that.

  2. Hello!
    I noticed one of my plants started getting the yellow curled/twisted leaves that you mentioned is caused by leafhoppers. I removed the whole plant to be safe and when I checked the underside of all its leaves I found 2 small cats. I’ve brought them in and have them in their own cage. Will they be fine having been on that plant?

    1. Hi Ashlee, the plant disease shouldn’t affect the caterpillars. Happy Raising!

  3. Help! Please! If I water my milkweed plant (from the base) it turns yellow, if I dont water it wilts. What can I do to save the plant?
    Thank you

    1. Hi Darby, you have to experiment to find that happy medium where the plants will thrive. Just break off yellow leaves and discard.

  4. The black spots on my curassavica look exactly like your picture so I’m going out right now to remove the unhealthy ones. I would like to try the hydrogen peroxide/water spray (I read thru the instrux) and BUT I’m not totally clear: can I do this while caterpillars or eggs may be present? I’ll look first, and remove any I find to safety, but of course I may miss some. Will this dilute spray harm them if some hits them by accident? what about residue remaining on leaves that they may eat?

    1. I also need to know if it’s safe to spray with H2O2 solution when eggs and cats are present?

      Tony, what do you think?

  5. Thank Tony, for the leafhopper damaged post. I thought it was from the heat and lack of rain this summer, but now I’m going to remove all of the yellow mishapen plants and hope for some healthy ones to come back up.

  6. Thank you so much for this! I have been wondering what the heck is wrong with my plant! Do I saturate the ground with hydrogen peroxide or just spray the surface? Thanks for all you do. You have been a tremendous help to me!

    1. Hi Claire, we typically use the h2o2 preventatively on small plants and soil before the plants come up. At this point, you could try cutting back the affected areas of the plant and then spray the remaining plant and soil…good luck!

  7. Hi – I just noticed that my otherwise healthy looking Asclepias tuberosa – butterfly weed – has yellow-ish leaves with dark green veins. It’s the sort of thing I see when my blueberries need more acidic soil – sclerosis. Is this something that happens to milkweed? The soil is probably already pretty acid but I will check it just to be sure. The other plants in the same bed look fine. I’ll send a photo if you can tell me how.

    1. Hi Lynne, I’m not a plant disease expert. We remove any problem leaves and treat soil preventatively with hydrogen peroxide which has worked well for us. For info on specific plant pathogens:

      What’s Wrong with My Plant?

  8. I have just begun raising monarchs. I have successfully released 4 with 2 chrysallis pending.
    I have several milkweed plants in my lanai. Within the last 2 days I have had several cats die. They have basically “keeled over” on a branch and died. Several seemed to have tried to chrysallis to early since I see the silky black pile on the leaf and they were very small.
    I have since removed my other cats onto another plant.
    I checked for spiders/mites etc but can’t seem to figure out what has happened.
    Any suggestions would be greatly appreciated. I thought of cutting down the plant totally just in case I missed something.
    Thank you.

  9. What is the best way to trim back my milkweed? I try and let the caterpillars do it, but in areas where there is rust the stem just seems to die.

    1. Hi Cait, I cut ours back with a hand pruner. Milkweed is pretty resilient. I would also try spraying the remaining stem with a hydrogen peroxide mix…see the chart linked in the article.

  10. I’m a first timer here and at home! I planted a butterfly and pollinator garden a couple of months ago. I have two milkweeds that are doing somewhat well. I have 5 monarch chrysalises safe inside now. While I’m not seeing many aphids (the ladybugs are getting them!), I notice one of my milkweed plants is growing yellow leaves at the bottom. The stems look ok, I guess, but like I said, I’m a newbie to all of this!! Any suggestions?

    1. Hi Tammy, I would just removed the affected leaves. Yellowing leaves can be from too much or too little water…adjust water levels to see if this makes a difference.

  11. I live in Fla and have what looks like white barnacles growing on my milkweed.

    We just had a ton of rain in the area.

    Any thoughts?!

    1. Hi Elana, sounds like a possible fungus…I would remove the affected leaves. good luck!

  12. Hi Tony,

    I have a ton of cats on my milkweed plant, mostly very young to about a week or so in size. About 75% of them seem to be trying to leave the plant. As a background, there must be at least 25 cats on the bush which is average size in a container about a year old. Lots of foliage since I trimmed it back. If there are too many on a plant, do they try to go elsewhere?


    Kelly in San Diego

    1. Hi Kelly, that’s way too many caterpillars for one plant. I would focus on adding more pesticide-free milkweed plants to your garden, or there won’t be enough to feed them all.

  13. I dug up a large tropical milkweed after last years first frost and it grew beautifully all winter. But as spring arrived, the leaves started looking sickly. I put it in a large glass spaghetti jar filled with water and just the leftover loose soil that was on the roots. It flourished this way. So I’m unsure why after many months it’s begun dying.

    Oddly- my neighbors yard has become overgrown with this same type milkweed which were healthy until this past week the leaves have a silvery blackish spotting along them. I see little black dots on the leaves as well- which makes me wonder if it’s an insect causing this?

    I was going to dig up most of their milkweed and transplant it. But if it’s sickly, obviously I don’t want to do that.

    Any ideas?

    I’d also like to add that last year I had the worst aphid infestation imaginable. The only thing that helped was a mixture of water and Stop n Shop organic plant based dish detergent. It killed the aphids, didn’t harm the butterfly weed and the cats seemed to be ok.

    1. Hi Allie…hard to say. it may perform better if it’s allowed to go through the winter part of it’s growth cycle, which it is able to do in perennial zones that still experience a true winter where the plant dies back. I’m not sure what those black dots are but taking some photos and asking around. I though maybe milkweed weevil eggs, but not sure…

      Here’s more short and long term strategies on:

      Stop Aphids from taking over Milkweed

  14. My milkweed on the patio have white mottling on the leaves. Is this from too much shade or what?

    1. Hi Barbara, fungus can be a problem with too much moisture or when plants are spaced too close together. I would removing the affected leaves and then spray the other leaves with the hydrogen peroxide mix listed in the post to see if that makes a difference. Leaves can also look mottled if infested with spider mites:

      Spider Mites Milkweed Pests

  15. Tony, do you have to use food grade hydrogen peroxide?

  16. I’m in Houston and have been raising asclepias for 25 years. Rather than fight the flies and hornets, I pluck off all the eggs and instars and raise them inside. The plants infested with aphids you have to wash off the aphids by hand using water in a squirt bottle. This way you can find caterpillars and protect the plants. The pheromone bag is a great idea; I’ve never seen any to buy. You can also find beetle eggs and remove them while killing aphids. I recommend wearing rubber gloves to keep your hands away from your eyes, and showering immediately thereafter if you are tending a large number of plants. Those little beggars will crawl up your arm and bite like chiggers and will drive you crazy for a day.

  17. I am doing a project on the Monarch Butterflies and it includes their decline. I am learning that the Tropical Milkweed (Asclepias curassavica) contains a protozan parasite Ophryocystis elektroscirrha that kills off the monarchs and the caterpillars. How can we detect if a plant is infected with the parasite? or is this something that is naturally occurring in the plant?

  18. I started several tropical milkweed from cuttings, and they were doing well until a couple of days, the leaves have tiny white spots and the leaf color is lighter green. Is this fungus? Or is it not getting enough sun?

    1. Hi Brenda, you could always try spraying leaves with a hydrogen peroxide solution and/or removing affected leaves as is listed in the post…

      1. Will the peroxide help with rust spots do the leaves and will it hurt the caterpillars ?

        1. Hi Michelle, we use h202 preventatively (in spring before milkweed emerges) and to overwinter plants indoors. When plant leaves get fungus, I remove them so it won’t spread. There are links in the post for how much to use…we use the chart for sick/fungusy plants. I don’t spray monarch eggs/caterpillars directly with hydrogen peroxide and not sure if/how it would affect them.

  19. I successfully raised over 50 butterflies at the beginning of the season and now the last 3 cages have been dying as the cats get nice size , they stop eating and just sit there for days and gradually die. Help, I am doing everything the same , I totally wash all the stems before bringing in to the cages. Everything is super clean. It has to be the milkweed, do you think the late season milkweed (tropical) could have oem that doesn’t wash off. Is there something I can use to wash the milkweed, a mild solution of ??? Please help, I still have 2 cages with cats.

  20. Hi there. My swamp milkweed leaves turned purple towards end of summer, then yellow, then red, and now they are falling off. I can’t find anything that says if this is normal Fall behavior or not (chicago, zone 5b). I’m especially concerned because this is only happening to one of my plants, although they do get different amounts of sun exposure.

    1. Hi Renee, this is how swamp milkweed goes out every season. I’m not sure what triggers it…perhaps cooler temps or less sunlight? Anyhow, all plants come back just fine the next season…

  21. Why are my plants’ leaves turning purple? I seems like the caterpillars also do not like those leaves/plants. He leaves look healthy otherwise. It is so odd! It appears like a fall changing leaf, but the leaves otherwise are healthy. Is this a water or soil condition issue?

    1. Hi Sara, this happens to milkweed in mid-late summer…most often on swamp milkweed. All I do is remove the most affected leaves, which are usually at the bottom. I’m not sure what causes it, but it’s never been a serious problem.

  22. The flowers on the tops of my tropical milkweed plants are wilting and dying. What could be causing this problem?

      1. Tony. I need help with my giant milkweed. I have 4 plant. They are
        Less than 1
        Year old. I live in central Florida. They all have the problem. It starts off with small
        Yellowish brown bumps all over the underside of the leaves. This develops on the leaves then the leaf yellows and drops off. Is there a way to send you an electronic picture. What is it. ? And how do I treat it?

  23. My swamp milkweed plants has reddish/purple edges on some of the leaves. Is it dangerous for the caterpillars to eat these leaves?

    1. Hi Katie, this is normal for swamp milkweed and I’m not sure what causes this. I usually remove/discard those leaves and it’s never developed into a serious problem. I have never heard of these leaves potentially hurting caterpillars, but I’ve never found any caterpillars on those leaves either.

  24. Hi Tony

    For the first time, my milkweed is covered with rust fungus. I tried the peroxide, but this is really bad and it did not help at all. I have a lot of milkweed- probably 15 different patches throughout my yard. All of it is infected. It happened in just a couple of weeks. The only plants not infected are the family jewels plants. Is there anything else I can do? I am thinking of cutting most of it down to stems and then spraying the stems and the ground and then hope there is new growth in August. Any suggestions? Do you know if those bacteria based fungicides are safe to use around monarchs?

    1. Hi Sandra, sorry to hear this. I’ve never heard of fungus spreading like this. I wonder what the issue is. We use the hydrogen peroxide preventatively, soaking the soil before the plants emerge in spring. This sounds like it would be a good idea for you next season. If the fungus is really bad, i’m not sure what option you have besides cutting back plants. I have not used bacteria based fungicides before and don’t know how they would affect monarchs or your local ecosystem. I would research thoroughly…good luck!

      1. Will the hydrogen peroxide spray hurt Monarch catepillars? Every bit of my milkweed has the rust colored fungus and my catties are eating them, so I hope the fungus doesn’t hurt them either. At least I know what to do next year. Thanks, Terry Greenwell

        1. Hi Terry, I use this more preventatively at the beginning of the season and overwintering plants indoors. I don’t spray h202 on eggs/caterpillars so I can’t say for sure if it would harm them. Spray early next season including the soil before plants emerge…good luck!

          1. Anyone ever use the dawn and water to see if it helps with rust? It does wonders for the aphids.

  25. Hey Tony, will spraying my milkweed with the hydrogen peroxide mix for fungus hurt monarch eggs or cats. I noticed a monarch butterfly around yesterday. It was the 1st one I’ve seen this season here in Massachusetts. I have a lot of yellow and black spotted leaves. Thanks for any advise.

    1. Hi Ralph, I only spray plants after I’ve checked for eggs and caterpillars. I would not spray while they are present. I typically remove the affected leaves…

      We mostly use h202 preventatively on the soil before the plants emerge in spring

  26. I have a gray film on the leaves of my plants. It is working its way up from the bottom of the plants. The leaves at the bottom are dried up and brown. Any suggestions? The plants are only about 2′ tall and bloom pods are just beginning to appear.

  27. I planted tropical milkweed in a sunny area in my moist garden about four weeks ago. Today it’s wilting and almost looks like it’s rotting at the base. We have had a lot of rain. Can They get root rot?

    1. hi Meg, if it’s not planted in well drained soil, root rot is a possibility, although i haven’t seen this with tropical milkweed in our northern region. We always turn over the soil a few times with a large shovel before planting.

  28. I have a number of butterfly weed transplants that I am trying to sell at a farmer’s market. Little yellow spots have developed on the leaves. Do you think this is fungal? Its been damp lately but the plants have been protected from being rained on directly and I have only been watering them minimally. Would the hydrogen peroxide possibly work?

    1. Hi Karen, I would remove the affected leaves and try spraying the plants (and soil) with hydrogen peroxide after…good luck!

  29. Tony, i sprayed with the 1 tablespoon 3% hydrogen per 8 oz water yesterday. I also removed a few of my plants with spots which were seedlingd last year so they were still small this year. I didn’t see anywhere that talked about how often you can spray. Do you know how often I can spray? And do you know how much to spray on the ground. Is it a light dusting or a drench? I want to get ahead of the fungus this year because last year I was far behind. Thank you

    1. Hi Gloria, I use it preventatively and haven’t had to use it during the season. I wouldn’t worry about overusing it though. I have never seen plants have an adverse reaction to it and I often use more than the charts. I soak the soil with the solution before plants start coming up. When spraying plants, make sure you get all sections and under the leaves too…

      1. Well, I found more spots today, removed the leaves, and sprayed the plants and sprayed the dirt with an almost 50-50 solution of 3% hydrogen peroxide. I figure they are either going to die for sure from the leaf spot (the1 tablespoon 3% peroxide per 8 oz didn’t do anything after the fact), so I might as well treat them aggressively and see what happens. I am sad though. I have a bunch of seeds to plant and no safe place to plant them now 🙁

  30. Hi! I recently bought and planted 4 nice sized Asclepias curassavica ‘Silky Deep Red’ – Red Butterflyweed plants. I have them in some pretty sunny places, like full sun and heat most of the day. I have some yellow/orange looking leaves. I am not sure if the plant is dying, the sun is killing these leaves or if this is normal. Because everything is freshly planted, I have hand watered all the new plants (all are drought tolerant plants, ground cover) and not sure if I have too much or not enough water now for the milkweed. I also have some butterfly bushes that have a little bleach looking area, but the milkweed is more worrisome for me. We are in SoCal with some really hot temps now. When planted a few weeks ago we were in the low 80s.

    I have not seen any aphids on them or other bugs for that matter. Thoughts?

    Much thanks!!

    1. hi Kat, if your plants are getting too much direct sun too quickly the leaves can burn. When you purchase new plants, it’s best to place them in a shadier area and gradually exposing them to more sun. If you cut back the burnt foliage, new growth should appear healthier…good luck!

    2. Milkweeds can take full sun with some wilt if temp goes up to 110 , temp around 80-mid 90’s should be ok …they don’t need much water after the first year

  31. I live in central FL and this is my second year raising monarch butterflies. My tropical milkweed is growing beautifully and I started seeing eggs in march but no cats. I have seen a lot of ants. Can they be eating the eggs and cats? What can I do to prevent this without hurting the plant or cats?

  32. Hi Tony, is it safe to spray milkweed with a baking soda mixture or would it be harmful to cats. Thanks

    1. Hi Ralph, I’ve never heard of anyone doing this, so I would suggest testing a plant. During the season, I never spray any foliar treatments on milkweed because monarchs use their feet and head to detect whether a plant is milkweed. I’m not sure if foreign substances would affect their perception…again, you can always test.

  33. Tony, what peroxide mixture did you use to water your dirt before plants began to emerge?

    was it the 1 tablespoon of 3 % for each cup of water?

    Did you soak the dirt or just spray on top of it?

    I have sprouts coming up that were fungusy last year. I also have seeds I want to plant in the same area. I don’t want to hurt them..

    1. Hi Gloria, hydrogen peroxide is actually food for plants, adding more oxygen to the roots. I have never hurt a plant by using too much hydrogen peroxide. I use the measurements for sick/fungusy plants…2 cups in a 2 gallon watering can of the 3%

  34. I’m in central Florida. All my tropical milkweed has the black spots and then turns yellow. They’re not planted very close together. I have used the hydrogen peroxide solution with some success. My question is I now have Monarchs laying eggs. Is it safe to use the solution on the plants with eggs? Should I just cut them all back and treat the ground and let them try to re-grow? I’m new to the this and don’t want to do anything that is going to worsen the situation.

    1. Hi Donna, in Minnesota I used the treatment preventatively in the soil before milkweed returns. I don’t think it would hurt eggs, but I would suggest testing it out before spraying them in mass…

  35. This was a very helpful article on fungus. The milkweed in my backyard raised bed is afflicted by this.

    I have also noticed that the leaves on some plants (even in other locations) are very small. Some are more red in color than green. I rarely see monarch eggs on them so the butterflies seem to be avoiding them for some reason. Do you know what would cause this stunted growth and discoloration?

    1. Hi Andrea, I don’t know much about specific fungus types, but the techniques listed have worked well to prevent and stop the spread of milkweed fungus in our northern garden. I would try them. I would also try to find others with first hand experience growing in your region, as they will probably have some more insight into what is most relevant growing in your region.

  36. This article mentions using a hydrogen peroxide mix to kill fungus. Does that affect the caterpillars negatively if later, eggs are laid on the plants and caterpillars eat the leaves? I would not spray with the solution if any caterpillars are on the affected plants but rather remove them, then spray. I’m just wondering about future eggs/cats.

    1. Hi Chris, I use it preventatively. I watered the soil with hydrogen peroxide earlier this spring (before plants start coming up). I also use it for overwintering plants indoors. I don’t generally treat plants outdoors after the season has begun. When there’s problem, I remove leaves/stems before they spread, and that has been effective for us.

      PS…I don’t think it would be toxic to future eggs/caterpillars, but you could always rinse off the plants with water if you are concerned.

      1. You water with a hydrogen peroxide and water preventable y? Which ratio would that be?
        I grew my seeds in 8 “cow pots” sitting in a plastic container sitting on heat mats and all under lights. Looking good at 3″ ,tall They seem happy alongside my tomatoes, peppers and eggplants. I am so interested in the H2O2 thing.

  37. Sounds like Kathy had a combination of problems. The tachnid fly has been covered. The brown chrysalises can be a bacterial infection. The wings that don’t open and deformed chrysalises would make me thing there has been an OE infestation. I would cut all the plants down to the ground and treat the stubs and soil as well as clean all the surrounding surfaces. If an infected butterfly lays eggs, they will be infected and can spread the OE to other healthy cats who crawl over the same plants. I had about 20 healthy butterflies emerge this spring, but the next 10-12 were all diseased. I suspect they came from the same butterfly and the sae thing would have happened in the wild, but it’s horrible to watch. Tropical milkweed is almost all you can find here, but it is suggested that it’s long season may discourage mmigration to their winter sites in Mexico and contribute to the OE problem.

  38. Hi Toney,
    I already get news from your web site but my issue is leaves turning yellow and falling off with lots of weird looking spots all over so I am thinking it might be a fungus of some sort and I am not sure of how to get rid of this problem without killing the eggs. I have searched for problem solving issues but am not sure what to try now.


    1. Hi Marcella, I remove problem leaves and discard. If an egg is on a problem leaf, you can cut off a small piece of the leaf (with the egg) and place it on a healthy cutting or leaf.

  39. Hi Tony,

    Things here are in a mess. I’ve been into monarchs for about four years. During that time I have raised a few hundred monarchs very successfully indoors. My success rate is really good.

    This year I’m really confused and scared. I’ve not been successful with the last 80+ caterpillars. Two different nurseries for my 5 gallon mildweed (tropical) plants. Both nurseries assured me their vendors don’t spray. In the spring I lost over 40 and called the first nursery. He was as upset as I was. Told me he trusted his vendor and told me he had a few calls with problems with the milkweed. I waited a bit and bought two more plants from a different nursery and tried again. As of this morning I have officially lost over 40 caterpillars again.

    The causes of the caterpillars deaths are all different. Some caterpillars are turning black and deflating, some are going into J too early and expelling magots, some of my chryaslis are brown, some are deformed, some have threads, some will allow the monarch to come out but the monarch is deformed. I’ve never seen so much damage and havoc before.

    I tried to call the second different nursery to get their input. Of course, they accept no responsibility and told me they know nothing about caterpillars etc. I then asked if anyone else had called with the same problem. They didn’t get any other calls. They then told me because I’m using tropical plants and not native that that was the problem. No way. They then told me because my plants were indoors that that was the problem. I then explained that I had been doing things this way for a long time and never before had a problem. They couldn’t offer me a solution.

    I don’t know where to turn to an answer. The nurseries don’t seem to be any help. They suggested I call the department of agriculture. Not sure I want to go there.

    Do you have any ideas on this? I sure would like to get some input so I can get back on the right track and stop killing all these caterpillars. Of course it could be the incoming monarchs and their eggs but to me that just doesn’t seem right. Thanks for your time.


    1. Hi Kathy, it sounds like you are having a major issue with tachinid flies. This can be avoided by bringing in eggs. Here’s more info:

      Tachind fly parasites

      As for the rest, are you in a region with increased mosquito spraying this season? I hope the disease pages link helps you figure out what’s going on…good luck!

      1. If i could offer a suggestion, find out who your local land grant university is for your state. In Indiana it’s Purdue. Most universities have a insect rearing lab that could answer your question. Of course as a Purdue entomology grad i think they are the best.

    2. There are flies that predate on the caterpillars and young chrysalides. The cats must be protected from them by putting the branches of milkweed in water and bringing them into a protective shelter with mesh sides and a zipper. I have hatched over 90% by protecting them. These shelters can be bought online.

  40. Tony, I’ve been concerned about my milkweed leaves turning purple and dropping off. It begins on the edges of the leaves and gradually the whole leaf becomes purple. This is happening on both our ground-planted swamp milkweed and also on our potted tropical milkweed plants. I’ve removed each purple leaf and examined them carefully. It doesn’t appear to be either a fungus disease or bug related, although at this point, I’m just not sure. I’m worried that if it continues happening in the weeks ahead, we may end up with not enough leaves for our monarch caterpillars to munch on. Any ideas/suggestions on dealing with this problem. Could it possibly be water related—not enough or too much?

    1. Hi Joanne, I’ve seen this before too and just removed the affected leaves. I’m not positive but it might be leaf scorch from too much sun. It can be especially bad with curassavica. It has never developed into a serious issue, so I don’t believe it’s a fungus/disease.

  41. If you spray the plant with hydrogen peroxide, won’t that kill the monarch caterpillar?

    1. Hi Maureen, whenever your treating plants with anything whether it’s a pesticide or considered monarch-safe, it’s always good idea to apply when there are no monarch eggs or caterpillars on the plant. I don’t think h202 would hurt them, but I’ve never sprayed it directly on them.

  42. I noticed I do have some plants with blackish spots and not so nice looking. I will definitely remove these. Thanks.

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