While keeping an eye out for Monarch butterfly caterpillars, I keep seeing the other types of insects that feed on Common Milkweed. I wrote an article recently introducing the Milkweed Tussock Moth caterpillar. This time, I’m talking about a type of beetle that is very common on Milkweed in southern Ontario, far more commonly seen that any of the caterpillars.
(There are actually several different red and black insects that feed on Milkweed plants in southern Ontario. One set are beetles and the other set are bugs. I’ll have to write a post on the bugs next.)
Milkweed Beetles Have Black Spots, Long Black Antenna, and Red Shells
Aside from the vivid black and red colouring, Red Milkweed Beetles are particularly noticeable because they have long black antenna. According to a University of Wisconsin website, they are a member of the long-horn beetle family, just like the Asian Long-horned Beetle that sometimes gets in the news when areas in North America are quarantined to eradicate it. These Red Milkweed Beetles, however, offer no threat to our forests and are native to North America.
Do Red Milkweed Beetles Eat the Leaves of Common Milkweed?
Yes, adult beetles do eat the leaves. The young, however, eat the roots of the milkweed plants and live underground. This is quite different from Milkweed Bugs which are an unrelated insect.
According to BugGuide.net, they have been reported on other types of Milkweed but appear to prefer Common Milkweed.
Does Eating Milkweed Make These Beetles Toxic to Predators?
When insects eat the sap in milkweed plants, they take in some chemicals called cardenolides (cardiac glycosides) that are poisonous to many mammals, birds and other animals. That does not mean that a Blue Jay who eats a single Monarch caterpillar will die: the jay will feel poorly though. Many insects that eat milkweed have bright colours, like these Red Milkweed Beetles, that may help cause birds and animals to avoid eating them again to avoid a second bout of illness.
The toxicity of Milkweeds, including Common Milkweed, is one of the reasons that these plants used to be classified as a danger to livestock by many jurisdictions. It was often mandatory to spray and remove Milkweed because it can poison poultry, sheep, cattle and other grazers. Now due to extensive lobbying from Monarch-lovers many places have repealed these laws so that Common Milkweed can be allowed to grow along roadsides and in private gardens.
Do I Need to Kill Red Milkweed Beetles If I Want to Help Monarch Butterflies?
No. Monarchs and Milkweed Beetles have co-existed for hundreds of years. There’s no need to destroy a normal healthy part of the food web just to help Monarchs.
Why I Look Forward to my Next Encounter with a Red Milkweed Beetle
According to one article I was reading, these beetles actually make sounds including a purr and a whine. I’ll have to try to tune in the next time I encounter some!
Related Reading
- Not Every Long-horned Beetle Is Endangering Our Forests
- Milkweed Predators: Milkweed Tussock Moth Caterpillars
- Milkweed Predators: Monarch Butterfly Caterpillars
- Milkweed Predators: Large and Small Milkweed Bugs
- Black and Red Box Elder Bugs Buzzing Up a Storm at Riverwood
- Further info on sounds made by Red Milkweed Beetles
Join In
Have you seen some of these long-horned beetles on your local patch of Milkweed? Did you hear any of them purr? Please share your sighting with a comment.
They eat leaves and flowers, no flowers no seeds I’ve started to pick them off in hopes of more seeds
Another way to propagate Milkweed is from the roots. I hope you get more plants!
I have just found 5 of the Red Milkweed Beetles today..
Thank you for sharing!
They are getting as far south now as Radcliff, KY. I had one on my porch the other day. My guess is migrating away from the wild fires and the wind took over from there.
I just saw on2 of these beetles on my milk weed. No I didnt hear them purr…
Just didn’t know what they are or if I should give them a burial or not. Lololo
I’d just let them be even if they won’t purr for you!
I’ve been letting the milkweed grow for the Monarchs but this is the first time I’ve seen red milkweed beetles — lots of them in my yard in Iowa. Don’t hear any sounds.
I hope you get some Monarchs! Thanks for sharing your experiences.
Pick it up and hold it next to your ear. Then you will hear the sounds
My 6-year-old son was bit by one of these beetles this afternoon. Are they dangerous to humans?
I’ve never heard of any danger from them but you can check with your doctor. Many insects will bite if they feel threatened. I see online that it’s more common to get bitten by a similar bug called a Milkweed Assassin bug. There’s a photo of one at http://bugguide.net/node/view/428983
I’m sorry I can’t tell you if it’s ok or not but I’ve never heard or seen anyone who was bitten.
Im pretty sure i just had one on my front porch im in central illinois. I got a picture of ir
They do fly around looking for partners and new plants–thanks for sharing!
I have never had these before this year. I was concerned at first because I have dozens of them all over my milkweeds! I’m glad I found your page, I’ll be listening for purrs now!
Yes, it’s nice that they are natural even if there are more of them sometimes than we like to see. I hope they purr for you!
This is the first year that I have had milkweed beetles on my MW plants in Denver.
They seem to do better some years than others. I’ve noticed them flying in the spring which must be how they find new plants. Thanks for sharing!
First year common milkweed came up in my yard. After seeing 2 monarchs am dismayed to see these red beetles chewing the milkweed to stubs. I live in southern NJ
If the Milkweed has rooted in your yard, you will have quite a bit more next year. The Milkweed Beetles don’t usually out-compete Monarchs so next year you may find both! Thanks for sharing.
I just encountered one of these beetles on my common milkweed plant. I’ve never seen them before and wanted to find info on them. Thank you for the info.
It’s interesting how many insects show up on Milkweed–thanks for sharing!
I also have these beetles all over my plants. Do I spray? If I do it will kill the Monarch butterflies. What about soap?
If you spray it will likely be bad for the Monarchs too. Personally, I just leave them on my plants.
I found one of these and they are decimating my milkweeds and a few other nearby leaves. I’m going to get rid of them….
Just be aware that Milkweed is well able to survive them and they are native too.
There’s one in my room in northern va! I don’t know of any milkweed in the area so this is new to me! He seems very confused haha
Yes, it sounds like a little lost dude!
Hi. Well I’ve just seen them for the first time, too. Detroit Michigan. And, I believe they were mating. 😏🤭☺️
I’ve grown a small amt of scattered milkweed forever, do sightings of these guys suggest it’s a good or bad year?
We have lots of them in our parks and the milkweed still seems to thrive. Hopefully yours will too!
I’ve had milkweed plants for many years now and today I saw 2 of them. Didn’t know what they were until I read ur article and found out that they are safe. I probably have more cuz I have tons of milkweeds. Saw a few monarchs recently too so I’m glad for that.
Around here the Monarchs, bugs and beetles all thrive on the milkweed and it doesn’t seem to kill the plants. Hopefully it will be the same with yours.
I have a milkweed beetle (July 14th S Ontario) next to poke milkweed. I also have orange milkweed in this garden. Does anybody know about this insect’s use of milkweeds other than common milkweed?
A quick look at BugGuide.net https://bugguide.net/node/view/2966 says they seem to prefer Common Milkweed but may use other species. I’m sorry I don’t have time to search further: it’s a good question!
I just saw my first beetle on the milkweed in my garden so I googled “red beetles” and got a bunch of Volkswagen’s! Lol… adding “insect” under “images” to my search brought me to your site. I’m in Waterdown (southern Ontario) and have never seen this beetle before. I thought it was something new and exotic…. so glad to read otherwise. Thanks!
They are pretty to look at but I’m glad they are native as they can be suddenly every where for a few days. Thanks for sharing yours!
Just saw one on my swamp milkweed and initally started to panic: longhorn beetle! It didn’t help that my 600-page tome on garden insects (Cranshaw) does not have any information on it. Thank Heavens I found your page and now I can rest easy. Thank you so much!
Luckily these things don’t permanently harm Milkweed and can even share the plant with Monarch caterpillars.
This morning while looking for traces of a groundhog family I was looking for Monarch cacoons…probably too early for that I came across one of the beetles on my dedicated milkweed patch. Was curious and googled red beetle with black spots and led me to you. No harm no foul.
I hope the Groundhogs are not eating your garden! Thanks for sharing your find!
I live in Las Vegas, NV and my yard is filled with the orange/black speckled crawling beetle. No milkweed or much ground vegetation available. We have several trees and bushes and desert landscaping. Are these harmful or dangerous?
Sorry but I’m pretty far away in Ontario so it may not be the same type of insect. Maybe a garden centre locally can help decide?
We have them in our backyard common milkweed patch in southeastern Pennsylvania. Glad to know what they are!
I noticed some on my milkweed today too–must be the season!
Just found some for the first time too in Greeley, CO. Only have 4 milkweed plants, found two red beetles. I don’t believe that I’ve ever had even milkweed plants before, that I know of anyway. Someone driving by told me that they were milkweeds and that monarchs lay eggs under the leaves?? Since the beetles aren’t harmful I’ll leave them alone.
Sounds like some interesting discoveries at your place that day! I hope you get some Monarchs stopping by too!
I live in the city of Buffalo New York and have nurtured a milkweed patch for a few years. I’ve seen 1 or 2 monarchs near them but as of yet no caterpillars. This year I was alarmed by these red and black insects. I wondered what they were . I hosed them off and they crawled back up. Thanks for identifying and informing on the nature of co existence… plant bug butterfly. I don’t like to kill anything but I do buy lacewings and praying Mantis eggs to deal with aphids on my cherry trees…thankfully milkweed patch far from trees
The Monarchs get all the press releases but there are so many creatures that benefit from your milkweed. On mine, I have quite a few types of moths and butterflies visit the flowers for the nectar. Hope yours continue to thrive!
I captured one. 1
Hope it was ok.
I just spotted one of these Bright red beetles on a large stand of milkweed in my yard just east of Denver. I’ve been here for 16 years & it’s the first time I’ve ever seen these.
Thanks for your article! I’ll just leave these beetles to munch away😊 I’ve seen many bugs, beetles & spiders on this milkweed, but I’ve never found any Monarch caterpillars on it😳. Do Monarchs come thru this area of the country or is it just This milkweed they don’t like? I don’t know what kind of milkweed this is. I love the scent of the flowers every year & bees go bananas for them, so I won’t ever get rid of my patch milkweed even if I never find any Monarchs. Just wondered if I should keep hoping.
I’m not really sure what their range is. I looked on iNaturalist
https://www.inaturalist.org/observations?place_id=any&taxon_id=48662
for sightings of Monarchs. The sightings do get sparse in the north-western US.
Sorry I don’t know for sure! But it sounds like your Milkweed is helping many other local insects live a happy life!
Found a pair mating on my milkweed. Now I have native bugs on my native plants ☺️ Thanks for the information. I’m in Pittsburgh PA. Couldn’t hear any purring tho as the birds are in full song this morning.
I have been growing milkweed for several years and have been raising monarchs from egg for the last 5 years. Usually about 20 adults per year, would like to raise more, but very time consuming and I live in Southern Ontario, so a fairly short season. they start laying eggs late June, early July and are done by mid September. Sorry, off topic there a little bit, LOL, this is the first year I have seen these beetles, quite a few on my milkweed, glad I found your site, and they can live in harmony with the Monarchs.
Just seen my first Milkweed Beetle today 6-69-2021. I was not sure what I was looking at, so I took a picture then found this site about these beetles. Interesting Beetle. “Mower County Minnesota”
I have these beetles In Wisconsin. Unfortunately I didn’t let the live.
I have these beetles In Wisconsin. Unfortunately I didn’t let the live. Will they be a pest to other plants too.
here in Central Pennsylvania I’m seeing these for the first time. Blazing fire engine red. It’s been so hot that the flowers are spent, some pods however. I’ll keep an eye out for developments. Thanks for the info.
Seeing these for the first time in my yard. This is also the first year I’ve been able to identify milkweed and avoid pulling it as a weed. Noticing an uptick in the monarch population in my area as more people embrace and plant milkweed
I’m glad that you are seeing a few more Monarchs. The weather is sometimes a factor, too. I notice our city now adds a few milkweed plants into many of its gardens!
Just had one of these on my shoulder underneath my shirt, could not figure out where this squeaky sound was coming from…. Eventually found it!
Eek! That must have been a surprise!
First time seeing one. Was not sure good or bad bug. Now I know. But do they bite? Noise sounds? To many other stuff going on to know.
Most insects will try to bite if they feel threatened (bird catching them etc). So I don’t touch as I don’t want to find out! Hope you’re ok too.
Thanks for the article. I saw some last year and another one today – that flew away and came back. I finally looked them up. We live in Wisconsin They weren’t in my insect books either. I’m leaving them alone.
I’m amazed at how many insects I find on Milkweed. I used to think it was only Monarchs that I should look for!
I saw these beetles for the first time today on the milkweed near my veggie garden. I live in Seward, NY. I didn’t try to touch one not knowing what they were but they did like the milkweed plants.
Thanks for growing milkweed–not only does it help Monarchs but it helps all these other native insects too!
appreciate this information I saw one of these buggers on my milkweed yesterday – wondered what it was.
You may soon see more! Like Monarchs, they are native. Thanks for sharing!
6.18.2023. Found red beetle with black spots and long antenna near milkweed plants. First time seeing one. Thanks for this website with photos. Live in Nebraska.
thanks for this article. Was just outside inspecting and found one munching away. I will leave him to it. Had a milkweed self plant in the front garden last year….now there are 7 of them!
Yep. Did a search on this strange Beatle on my dad’s plants it’s definitely the bigger. I also see it is indeed a milkweed plant here in Illinois.
My husband and I just bought our first home in Michigan, all our neighbors spray for milkweed but after educating a few of them on monarchs and the importance of milkweed some have let a few patches grow. We’ve left a large patch in our yard and have seen our first monarch a couple days ago! We are also seeing these beetles and I was worried at first about what to do. But after reading your post I am happy they are there.
I am worried about the other bugs though, earwigs, ants, box elder bugs, Japanese beetles, sweat bees, flies, and honey bees (I am sure honey bees are fine- and my other neighbor has a hive so we are glad to help the honey bees as well) are there any other insects/animals we should watch out for that could be hazardous or dangerous for the monarchs?
I forgot I saw yellow jackets too… I know they can be predatoristic as well… should I be watching/ spraying for them?
I don’t think spraying does much good for yellow jackets, and it might harm one of the “good guys” so I wouldn’t personally.
It’s actually ants that do the most harm by taking the Monarch eggs away. But there does not seem to be a safe way to stop that. But overall, it seems that Monarchs will do ok if we just let a bit of Milkweed grow here and there for them.
I saw my first Red Milkweed Beetles today. I’ve grown milkweed for several years here in Colorado Springs, but never noticed the beetles before. So far, I don’t know if I’ve ever attracted any Monarch butterflies, but my milkweed does attract ladybugs and other insects. I’m glad to learn about the Red Milkweed Beetles!
All of these native creatures are benefitting from your kindness in growing milkweed!
I did not notice the antennae. I found it nested inthe leaves of an oleander bush. I am will be 90 in Dec. And have worked in my yard all my life. I have never seen an insect like this in my lifetime!!!
There’s always something new in a garden–I’m not sure this insect was what you were hoping to see though! I hope the flowers grow well this year!
Just saw a couple in Bay City Michigan
Sounds like they are having a good year!