Milkweed Bug infestation of Butterfly Weed

by May 3, 201112 comments

Butterfly Weed (Asclepias tuberosa) and Liatris spicata
Pictured here is the original idea — purple Liatris spicata spikes paired against orange Butterfly Weed (Asclepias tuberosa) blossoms in one of our backyard flower beds. Both attract butterflies, both are easy-to-grow perennials, and both have similar tight flower clusters — but there’s a nice contrast of forms and colors. Last spring, we decided to expand on this, by devoting one flower bed entirely to this combination. At that time, we had never heard of the Milkweed Bug.

Now, we did know that Liatris tends to get chewed on. It is not unusual to find a new spike felled every few days by vandal rabbits. Our hope was for strength in numbers. If we planted a whole bunch of Liatris, then a downed spear here and there would not be missed.

Liatris spicata corm
Butterfly Weed (Asclepias tuberosa) growing in backyard flower bed, Racine, Wisconsin
Amy bought a plastic box of 25 Liatris corms for $5 at Menards and carefully planted them root-side down in the flower bed where we had already established a good many small Butterfly Weed plants.

Why Butterfly Weed?

Butterfly Weed (Asclepias tuberosa) is so named not only because butterflies feed on its nectar, but because it is a host plant for the Monarch Butterfly (Danaus plexippus) — as are other Asclepias species, such as the less beautiful Common Milkweed (Asclepias syriaca). Monarch moms lay their eggs on these plants, which are then eaten by the resulting caterpillars.

While Butterfly Weed provides nutrition for the Monarch caterpillars, it also arms them with a toxin which makes Monarch Butterflies distasteful to predators. I was hoping this might also offer some protection to the interspersed Liatris.

Monarch butterfly caterpillar (Danaus plexippus) feeds on Butterfly Weed (Asclepias tuberosa) in Racine, Wisconsin
Instead, within two days of Amy’s careful planting, marauding Gray Squirrels dug up 24 of the 25 Liatris corms, chewing on each one before discarding it to dig up the next.

Only the Butterfly Weed (and one lonely Liatris) remained. In time, Monarch Butterflies did indeed find our patch. They danced happily from plant to plant laying eggs all over. Before long, we were spotting numerous caterpillars and were very pleased to play some small part in the survival of this majestic threatened species.


Milkweed Bug (Oncopeltus fasciatus) on seed pod of Butterfly Weed (Asclepias tuberosa)
Milkweed Bugs (Oncopeltus fasciatus) mating on seed pod of Butterfly Weed (Asclepias tuberosa)

Milkweed Bug infestation

Then the first of the peculiar bugs appeared — orange and black guys which flew a little, but mostly just hung out on our Butterfly Weed plants. Some of the bugs would pair off, rear end to rear end. As we read online, this is how Milkweed Bugs (Oncopeltus fasciatus) mate. Soon, there were lots and lots of Milkweed Bugs all over our Butterfly Weed.

Besides mating, Milkweed Bugs eat milkweed seeds. They have a long mouthpart known as a “rostrum” which they use to pierce the plant’s seed pods and suck juices right out of the seeds themselves. As with Monarch Butterflies, the toxic glycosides from the plant make the bug distasteful to predators, and their orange color serves as a warning. Birds know not to eat them.

As far as I could find out, there wasn’t much we could do to control these bugs. Poison would also harm the very butterflies and birds we want to encourage. One article I read suggested squishing the bugs individually, but I just don’t have that kind of free time.

Within a couple of weeks, our once beautiful Butterfly Weed looked discolored and desperate. Its withered seed pods opened prematurely to release their downy contents before all hope was lost. Not fluffy enough to fly, the fuzz mostly clung to the ratty plants while pulsing swarms of Milkweed Bugs backed into each other in ecstatic frenzy.

This year, all of those Butterfly Weed plants have been cleared out. We’ll keep the one or two plants we have elsewhere. Liatris, however, will get another try. This time around, Amy has planted 50 corms — and staked a wire mesh over them to thwart the squirrels until they start sprouting.

Green wire mesh staked over flower bed as squirrel protection

Our solution: Pull off the seed pods

I say this below in the comments, but I thought I would add it here as well: We have had no further infestations of Milkweed Bugs since we started plucking the seed pods from the Butterfly Weed as soon as they appear. This has no adverse effect on the plant. In fact, it seems to promote a weak second flowering. We have no use for the seeds, and this also prevents their silky floss from blowing all over the yard.

This post is tagged: butterflies, featured, flowers, gardening.

12 Comments

  1. Craig

    This is just a thaught.All of the butterfly attracting blooms have gone to seed and you now have catterpillers happily munching on your plants would it now be possible to wrap the plants with a light fabric to keep the bugs out? Of course timing would have to be watched so the larvea could be let out to pupate( maybe) but that should be doable.
    what do you think?

    Reply
  2. Patrick Warren

    I planted a moderate patch of butterfly weed and also discovered those pesky Milkweed Bugs. What I’ve changed is instead of one or more moderate or huge sized patches to just a couple of few plants throughout the entire yard. When any Milkweed Bugs appear I use a pair of leather work gloves and squish them and leave them dead around the plants.

    This is working well enough as the Monarch caterpillars are now getting the upper hand and I’m now breeding on average 4 to 6 monarchs every other week or so. I see them flying around my yard every day, feeding, breeding and laying eggs.

    To keep aphids under control I’ve planted dill weed, catnip, oregano, basil, onions, chives and leeks nearby or within the butterfly weed. I also let wasps make nests nearby as they feed on aphids.

    Reply
    • Debi Elisabeth

      so there is Nothing you can spray on the black and red aphids without hurting the milkweed for the monarchs to lay eggs?? Also, do the aphids eat the eggs as well?

      Reply
      • Patrick Warren

        I don’t think aphids affect the monarch eggs, just the plants and they are somewhat less destructive than the Milkweed bugs (beetles), which seem to attack the flowers and seed pods and end up destroying them. Anything you could possibly use for the aphids could have a negative affect on the monarch eggs and caterpillars. When any I have in the yard become badly infected with aphids or beetles I cut them down and move any caterpillars to others that are not infected.

        Since planting the above deterrent plants around the Butterfly Weed I have not had any aphid infestations.

        Reply
  3. keepitsimple 1

    Hi. I know this posting is rather old but I too am trying to find out what to do with these red bugs invading & destroying my butterfly milkweed plants. Not only do they suck on the seed pods but they destroy the leaves. A number of plants also look rather sick. It also seems that the monarchs are avoiding the milkweed once these bugs show up & set up shop. I am not too comfortable squashing them. They are just too fast but I noticed that they drop to the ground once you get near them. So I devised a plan of attack. I put some soapy water in a tall chinese takeout soup container. I gently placed the container right under their little gathering and went after them with a one inch paint brush. Some dropped right into the soapy water and drowned. Others ran under the leafs but again I placed the container right under the leaf & flicked them in. I also went after the little ones hidden at the tops. I just waited a bit to allow the others that got away to regroup on the leaf or stem then I swept them in the container too. I had 100s of bugs on the first day. I patrol the milkweed once a day with my container & brush. I do believe I have them under control & I am seeing more caterpillars & plenty of healthy leaves to chew on. Just thought I would spread the word. DG

    Reply
    • Roxanne Jones Young

      So helpful! I just instituted my “butterfly garden,” and have these nasty red/black bugs and then found some spore-looking orangy teeny-tiny creatures on the underside of some milkweed leaves. Any suggestions? Rx

      Reply
      • keepitsimple 1

        Hi. Great on the butterfly garden. You’ll love it. The Monarchs are heading down south for the winter. I have a lot of healthy milkweed & other butterfly friendly plants
        for them. The milkweeds now have the seed pods. So when they have reached full
        size I clip them, dry them out and plant in pots on the patio until they are tall enough to gently place in the ground. They go into shock quickly so be gentle when transplanting. When you plant in the pot & the ground, I put half of the dead fallen leaves at the bottom for nutrients. I do this many times throughout the year with leaves of other plants I trimmed. That’s the secret of my green thumb. I talk to them too and they love it. They are living beings too and they do respond to special human attention. For the plants already in the ground I dig up holes/pockets around the plant & stuff with fallen leaves then cover. The plants love it. We have sandy soil so there isn’t much nutrients for them. I also place a string around the base to keep them upright and closer together in their groups. If you don’t they will grow all
        over the place. I don’t have much room on the sides of the houses.

        I also work on some of my retired neighbors flower gardens and planted milkweed all over the place. The butterflies make the rounds around the houses and my mom loves it. I showed her the cats & the butterflies just out of the cocoon drying its wings & she said, “Plant more.” It’s wonderful to see the whole process. Keep in
        mind the wasps also make the patrols too. They will attack and kill and
        butterfly with wet wings just out of the cocoon. There’s not much you can do
        with that. I have cats also on the seedlings on the patio. They are next to the
        evergreens so they can have a safe place for the change. One day, I saw what I
        thought was a monarch dying in the middle of the sidewalk. I gently pick her up
        and saw that she had just come out of the cocoon and her wings were still wet.
        I put her under the evergreens so she could dry out her wings and take flight
        without being harassed by wasps. That’s the one I showed my mom. When you see
        that, it touches your heart and you understand why you do this at a deeper
        level and you want to do more. I’ve had to deal with violence all my life so this is a real treat. This is also great to help manage chronic pain. It gets my mind off all the pain I am in. It’s also great to get out in the sun & fresh air. I listen to the birds sing & the squirrel chatter. I was too busy before to notice this. Now I appreciate it and all the critters including the lizards that hop around. They have amazing personalities too and eat the bugs I dig up. One day, I dug up a bug & a lizard darted out from under the evergreens to get it. I said, “It’s ok, it’s all yours. Enjoy & thanks.”

        Yes, those red bugs are horrible on milkweed. You need to get them under control. Try using the plastic container with soapy water so they don’t fly out. Find a one inch paint brush from the garage and plan your attack. Just flick them in. It’s rather easy once you get the hang of it. The word is out on my battle plan so they will scoot
        around to the other side of the stem or leaf. I end up talking to them too,
        “Ok, I see you. You are out of here.” Call me crazy but its a little game
        between us. Always check the bloom tips, the red bugs have their nurseries in
        there. The plant looks sick, you have bugs. Make sure you also plant more seeds
        at the base of all your in ground milkweed for new plants. Eventually, I clip
        the old thick ones down to make room for the newer plants.

        I did eliminate the red bugs from all the plants but I recently saw a few which were swept up right away. It did have a nursery at the top. I use the same attack on the yellow aphids too. They are a bit harder to sweep off but work at it gently with the
        brush over the container and they too will drop in. They too hang out at the
        blooms so gently get rid of them too. With one hand I gently bend over the
        bloom over the container in the same hand then work gently with the brush. This
        is also how I clean out the red bug nurseries in the blooms. Work a little at a
        time if you have a large garden. Eventually, you will get them all. They will
        drop to the ground if disturbed. With gloves I just scoop them up & throw
        them into the water too. They will bury themselves so be quick. Don’t use any
        pest control. Even weed spray will kill monarchs.

        Enjoy your garden and all the other butterflies that visit too.

        Reply
        • Hiram Abiff

          I found Milkweed Bugs on my plants the first year I planted them. I just put a cottage cheese container with a mixture of water and dishwashing detergent under the branch and give it a little tap. All the bugs fall off into the soapy water and sink immediately to the bottom. After I few days I don’t see them anymore.

          Reply
  4. amyinnh

    How’d your liatris do? It likes a lot of sun, else it leans. And it looks like they’re under a tree in your photo above.

    Reply
    • Mark Czerniec

      The liatris that survived the squirrels are fine. They’re not under a tree, get plenty of sun, and increase each year.

      Reply
  5. Jen Houchin

    Can soapy water be sprayed or will this hurry the monarchs also?

    Reply
    • Mark Czerniec

      I imagine that anything which deters insects in general will also deter Monarchs — and the caterpillars munching the leaves probably don’t want soap with each bite.

      Reply

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