Red Milkweed Beetle: All You Need to Know in a Quick Guide

The red milkweed beetle (Tetraopes tetrophthalmus) is a fascinating insect that stands out because of its vibrant red color and striking black markings. As part of the long-horned beetle family Cerambycidae, these beetles are found on milkweed plants, serving as both a pollinator and a consumer of the plant.

Milkweed plants are essential to many insects like monarch butterflies, but they are also home to red milkweed beetles. The beetles play a role in the ecosystem by consuming milkweed leaves and stems. However, due to the toxins present in milkweed, these insects tend to develop a defensive coloration, serving as a warning sign to other animals to stay away.

Red milkweed beetles are not the only insects found on milkweed plants. Other bugs, such as the large milkweed bug (Oncopeltus fasciatus), also thrive on these plants and contribute to the plant’s overall health. As you explore milkweed plants, keep an eye out for these colorful and intriguing insects.

Overview of the Red Milkweed Beetle

Taxonomy and Classification

The Red Milkweed Beetle (RMB), scientifically known as Tetraopes tetrophthalmus, belongs to the longhorn beetle family, Cerambycidae. This beetle is a member of the genus Tetraopes, comprising 26 different species of milkweed longhorn beetles, each with a preference for a different milkweed species (source).

Physical Characteristics

  • RMB has a striking color pattern: red with black spots or markings.
  • Known for its long antennae that bisect the beetle’s eyes, giving the appearance of four eyes (source).

Range and Habitat

RMB is mainly found in the eastern United States, particularly in Wisconsin. These beetles’ primary habitat consists of milkweed plants, where both their larvae and adults thrive. The larvae bore into the roots and overwinter underground, while adult RMBs emerge in late spring, feeding on the foliage and leaves of milkweeds (source).

Example Table: Comparison of RMB with Other Milkweed Beetles

Feature Red Milkweed Beetle (Tetraopes tetrophthalmus) Milkweed Leaf Beetle (Labidomera clivicollis)
Family Cerambycidae (longhorn beetles) Chrysomelidae (leaf beetles)
Color Red with black spots Red with black stripes
Antennae Long, bisecting eyes Short
Primary Host Plant Milkweeds Milkweeds

By understanding the taxonomy, physical characteristics, and habitat of red milkweed beetles, readers can better appreciate these fascinating creatures.

Life Cycle and Behavior

Eggs and Larvae

The life cycle of the red milkweed beetle (Tetraopes tetrophthalmus) begins when a female lays her eggs on the milkweed plant. She usually deposits small clusters of about 25 to 35 eggs1. While the eggs are initially light yellow, they turn reddish before hatching. Once hatched, the larvae start feeding on the milkweed, making tunnels in the roots2.

Example: In the Milkweed Longhorns species, larvae overwinter below ground3.

Pupation and Adult Stage

After passing through several instars (developmental stages), the larvae transform into pupae and eventually emerge as adults. Adult red milkweed beetles are characterized by their red color and black spots or markings4. They are often seen chewing milkweed foliage and leaves during late spring5.

Comparison Table:

Feature Adult Red Milkweed Beetle Milkweed Longhorn Beetle
Size 1/2 to 3/4 inch long1 Slightly variable3
Color Red with black spots4 Red with black markings3
Overwinters No1 Yes, as larvae3
Food Milkweed foliage, leaves5 Milkweed roots, foliage3

Bullet Points:

  • Red milkweed beetle larvae overwinter in milkweed roots2
  • Adults emerge in late spring5
  • Red and black colors warn predators of their toxicity4

Relationship with Milkweed Plants

Feeding and Nutrition

Red milkweed beetles specialize in eating milkweed plants1. They target different species like common milkweed and swamp milkweed. The adult beetles chew on foliage and leaves, while their larvae bore into the roots2.

Here’s a quick comparison of their feeding preferences:

Life Stage Milkweed Part Consumed
Adult Foliage and Leaves
Larvae Roots

Toxic Compounds and Defense Mechanisms

Milkweed plants contain toxic compounds, such as those found in dogbane and oleander3. Red milkweed beetles tolerate these toxins and use them for their defense mechanisms. When consuming milkweed, they sequester the toxins in their bodies and display bright red colors as a warning to predators4.

Benefits of sequestering milkweed toxins:

  • Increased defense against predators
  • Warnings to potential threats through bright coloration

Impact on Milkweed Populations

While red milkweed beetles can impact milkweed populations through feeding, they are not the only insects that rely on these plants5. Other insects include milkweed longhorns and oleander aphids. However, healthy milkweed populations can generally support the various insect species that rely on them for their survival.

Relationship between red milkweed beetles and other milkweed feeders:

  • Both rely on milkweed plants for survival
  • Healthy milkweed populations can support multiple insect species

Red Milkweed Beetle and Other Insects

Coexistence with Monarch Butterflies

Red milkweed beetles share their habitat with monarch butterflies. Both insects feed on milkweed plants, but have evolved different strategies to overcome the plant’s toxins. Monarch caterpillars only feed on leaves, while red milkweed beetles eat both leaves and roots.

  • Monarch caterpillars stick to eating leaves
  • Red milkweed beetles eat leaves and roots

Different Milkweed Bugs

There are various milkweed bugs found on milkweed plants, including:

Name Size/Color Species
Large Milkweed Bug ¾” long, orange Oncopeltus fasciatus
Small Milkweed Bug smaller, black and red Lygaeus kalmii
Milkweed Leaf Beetle red, black spots Labidomera clivicollis

Predators and Pests

Milkweed bugs face several predators, including birds and spiders. Milkweed plants also host various pests, such as milkweed aphids and milkweed tussock moths. These insects rely on the milkweed toxins for defense.

  • Predators: birds, spiders
  • Pests: milkweed aphids, milkweed tussock moths

Monitoring and Control

Identifying Red Milkweed Beetle

Red milkweed beetles (Tetraopes tetrophthalmus) are an easy-to-spot insect found on milkweed plants. They can be identified by their:

  • Orange-red color with black patches
  • Long antennae that bisect their eyes
  • Total length of around 0.5-0.75 inches

This beetle is part of the long-horned beetle family (Cerambycidae) and is not an invasive species1.

Preventing Damage to Garden Plants

While red milkweed beetles typically feed on their host plants, milkweed, they might occasionally cause damage to other garden plants. To prevent this:

  1. Plant strategically: Place milkweed plants away from other valuable garden plants.
  2. Inspect plants regularly: Keep an eye out for signs of damage and any beetle populations.

Natural and Chemical Management Strategies

Managing red milkweed beetle populations in your garden can be achieved through a mix of natural and chemical approaches. Here are some options:

  • Maintain balance: As these beetles are native to North America, they usually don’t cause significant problems. Keeping a balanced ecosystem in your garden can help prevent major infestations.
  • Manual removal: If you see a small number of beetles, simply remove them with a garden hose or by hand.
  • Pesticides: In more serious cases, consider using chemical pesticides. However, be cautious as pesticides can also harm beneficial insects.
Method Pros Cons
Manual removal Eco-friendly, no harmful effects on other insects Time-consuming, not effective for large populations
Pesticides Effective for large infestations Can harm beneficial insects, may cause environmental harm

In conclusion, monitoring and controlling red milkweed beetles is essential for maintaining a healthy garden. Knowing how to identify the beetle and applying prevention and management strategies can help keep your garden plants safe.

Additional Information

Unique Features and Anatomy

The Red milkweed beetle (Tetraopes tetrophthalmus) belongs to the long-horned beetle family (Cerambycidae) and displays some interesting features:

  • Their color: Red milkweed beetles are primarily orange-red with black markings.
  • Their eyes: These beetles have a compound eye that is bisected by their long antennae, giving the appearance of having four eyes.

Conservation and Ecological Role

The Red milkweed beetle plays several roles in its ecosystem and its conservation:

  • They mainly feed on milkweed plants, metabolizing the plant’s toxins to make themselves poisonous to potential predators.
  • Their grubs or larvae stage consume milkweed roots, thus aiding in the control of these plants.
  • As herbivores, they help to maintain a balance in the plant population within their habitat.

The Red milkweed beetle’s anatomy and ecological roles showcase the unique adaptations that allow it to thrive in its environment and contribute to the overall ecosystem.

Footnotes

  1. Milkweed Bug | NC State Extension Publications 2 3 4 5

  2. Bugs with Beth: Milkweed Leaf Beetle & Red Milkweed Beetle 2 3

  3. Milkweed Longhorns Milkweed Borers; Milkweed Beetles – MDC Teacher Portal 2 3 4 5 6

  4. More than monarchs – What are those bugs on my milkweed? 2 3 4

  5. Red Milkweed Beetle (Family Cerambycidae) – Field Station 2 3 4

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Red Milkweed Beetle

 

Is this a Longhorne Beetle?
July 20, 2009
This little guy is hanging out on a milkweed plant by my pool. He’s too pretty to smush. Really bright reddish orange with some funky black spots. If he is a longhorne, and he certainly has the antenne for it, what plants will he go for? Right now, I’m happy to leave him be. He can bore into all the milkweed he’d like.
JMR
Pennsylvania

Red Milkweed Beetle
Red Milkweed Beetle

Dear JMR,
The Red Milkweed Beetle, Tetraopes tetrophthalmus, is in fact a Longhorned Borer Beetle and the food plant for both adults and larvae is the Milkweed.
These Red Milkweed Beetles squeak when handled.

Letter 2 – Red Milkweed Beetle

 

what is it?
I found several of these on milkweed flowers and leaves today and watched this one eating the leaf in the picture. I live in southern Ontario, Canada. Can you tell me what it is? What else it likes to eat?
love your site, and BugGuide, too!
Valerie

Hi Valerie,
The Red Milkweed Beetle, Tetraopes tetraophthalmus, is a Longhorn Borer. It feeds exclusively on milkweed. The larvae bore in the stems and roots and the adults are immune to the poison in milkweed. These beetles can squeak loudly by stridulating their thoracic areas together.

Letter 3 – Red Milkweed Beetle

 

milkweed beetle(s)?
3 pictures attached, choose your favorite. In the garden in Northwest Ohio. I asked my father to get a good japanese beetle photo for you with his macro lensed camera, hopefully he comes through… There were two of them on the plant.
John

Hi John,
Thanks for the photo of the Red Milkweed Beetle on its host plant. We eagerly await that Japanese Beetle image as well.

Letter 4 – Red Milkweed Beetle

 

Please help ID this beautiful bug
I love finding new specimens of anything living and would love it if yo> could help me ID this one. We live in the South East corner of Michigan and found him hanging out on the trash can lid outside. What could he (or she) be?
Bekah

Hi Bekah,
This is a Red Milkweed Beetle or Milkweed Longhorn, Tetraopes tetraophthalmus. They squeak by rubbing together rough areas on their thorax when handled. Larvae bore into stems and roots of milkweed.

Letter 5 – Red Milkweed Beetle

 

Red and black bug id, please!
Location: Anoka county, MN
July 10, 2011 11:16 am
Hello, I found this bug on a milkweed plant on July 3rd, 2011. I’m curious as to what it is. I’ve tried doing some searches on the internet without much luck. Thanks in advance for the help!
Signature: Kari Skordahl

Red Milkweed Beetle

Hi Kari,
This is a Red Milkweed Beetle,
Tetraopes tetrophthalmus, one of the Longhorned Borer Beetles in the family Cerambycidae.

Letter 6 – Red Milkweed Beetle

 

Subject: Feisty Milkweed
Location: Central Minnesota
June 29, 2016 5:24 pm
Howdy!
I live in central Minnesota (Upper Midwest) and I’m growing milkweed around my house (along with some other flowers and veggies of the like).
When trying to get a snap shot of a white/tan butterfly with grey borders, one of these little guys ran right up to my face and threw his hands about.
I’ve seen them somewhere, but I don’t remember what they’re called or if they’re beneficial to the milkweed? I was hoping to attract Monarchs and I’ve got my fingers crossed that they’ll happen someday.
Signature: BadWithBugs

Red Milkweed Beetle
Red Milkweed Beetle

Dear BadWithBugs,
There is an incredibly complex ecosystem associated with Milkweed and many insects, like the Monarch, feed solely on Milkweed.  This Red Milkweed Beetle,
Tetraopes tetrophthalmus, is an insect that feeds on Milkweed.  According to BugGuide:  “Eggs laid on stems near ground or just below surface; larvae bore into stems, overwinter in roots, and pupate in spring; adults emerge in early summer.”  Of the genus, BugGuide notes:  “Adults feed on leaves of milkweed (Asclepias); larvae feed externally on roots of host (root feeding is unique among Lamiinae).”  We have a nice image on our site of a Red Milkweed Beetle feeding on Milkweed with a Monarch Caterpillar.

Letter 7 – Red Milkweed Beetle

 

Subject:  Really cute bug
Geographic location of the bug:  Missouri
Date: 09/13/2017
Time: 11:25 PM EDT
Over the summer, I found this really neat bug. I have no clue what it could be called, but it sure did like hanging around the nature park’s garden!
How you want your letter signed:  Mark

Red Milkweed Beetle

Dear Mark,
Though it was on grass when you took the image, this is a Red Milkweed Beetle or Milkweed Longhorn in the genus
Tetraopes, which is always found in association with milkweed, its sole food plant.

Letter 8 – Red Milkweed Beetles Mating

 

Some lovers for your bug love page
These beetles, not too sure what they are, we’re gettin busy on the underside of a leaf, amazing they didn’t fall off. Enjoy!
Becky

Hi Becky,
If photos we have seen are any indication, Red Milkweed Beetles must spend their entire adult life mating.

Letter 9 – Red Milkweed Beetles Mating

 

longer lady bug w/ antennaes
Hi,
I was taking photographs of flowers and insects on a local lake here in maryland and got a chance to take shots of this bugs. At first I thought they are lady bugs but these are longer and a little bit bigger. Any help is appreciated. Thank you.

These are Red Milkweed Beetles, Tetraopes tetrophthalmus. The are frequently encountered while mating.

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

5 thoughts on “Red Milkweed Beetle: All You Need to Know in a Quick Guide”

  1. Should I be trying to get rid of these beetles.. Do they do harm
    to the milkweed so monarchs won’t lay eggs on the leaves??
    I have seen a couple of monarchs this year and would love to
    have them on my milkweed!

    Reply
    • To the best of our knowledge, the Red Milkweed Beetle will not deter the Monarchs from laying eggs. We would allow the milkweed ecosystem to survive.

      Reply
  2. Should I be trying to get rid of these beetles.. Do they do harm
    to the milkweed so monarchs won’t lay eggs on the leaves??
    I have seen a couple of monarchs this year and would love to
    have them on my milkweed!

    Reply
  3. Bonnie and bugman,

    I have them abundantly in my back yard on the milkweed plants. They like mature milkweeds and they chew up the leaves. I agree the beetles do not seem to deter the monarchs from laying eggs, but the monarch mothers prefer not to lay eggs on the damaged milkweed leaves. I cut back on the milkweeds that I don’t want them on so the new plant emerge to invite the monarchs to lay eggs.

    Reply
  4. Bonnie and bugman,

    I have them abundantly in my back yard on the milkweed plants. They like mature milkweeds and they chew up the leaves. I agree the beetles do not seem to deter the monarchs from laying eggs, but the monarch mothers prefer not to lay eggs on the damaged milkweed leaves. I cut back on the milkweeds that I don’t want them on so the new plant emerge to invite the monarchs to lay eggs.

    Reply

Leave a Comment