Red Flat Bark Beetle: Essential Facts and Tips

The Red Flat Bark Beetle is a fascinating insect that plays a significant role in the health of forest ecosystems. These beetles, native to North America, can be found at various elevations and are known for their unique appearance and behavior. Understanding the Red Flat Bark Beetle is crucial for forest management, as infestations can greatly impact the health and sustainability of trees.

These beetles are attracted to weakened or stressed trees, making them important regulators of forest health. For example, their activity can help prevent the spread of disease, thereby ensuring that only the strongest trees survive to reproduce. On the other hand, severe infestations can lead to tree mortality, which has implications for timber production and wildlife habitat.

Red Flat Bark Beetle Basics

Classification and Taxonomic Status

The Red Flat Bark Beetle (Cucujus clavipes) is a member of the order Coleoptera and belongs to the family Cucujidae under the genus Cucujus. This family of Cucujidae comprises various flat and elongated bark beetles.

Physical Description

Red Flat Bark Beetles are small insects with the following features:

  • Distinctly flat body shape
  • Bright reddish-orange color
  • Size ranging from 7 to 12 mm in length

These traits allow them to reside under tree barks, providing a protected habitat. The beetles are also known to display excellent freeze tolerance, making them well-adapted to colder environments.

Trait Red Flat Bark Beetle
Family Cucujidae
Genus Cucujus
Order Coleoptera
Body Shape Flat
Color Reddish-orange
Size 7mm – 12mm
Habitat Under tree barks
Adaptation for cold Good freeze tolerance

In comparison to other beetle species, the Red Flat Bark Beetle has a unique flat body shape and bright coloration, which distinguishes it from many other bark beetles. Being small and flat allows these beetles to easily hide between barks of trees, making them less susceptible to predation.

Habitat and Distribution

Geographical Range

The Red Flat Bark Beetle is typically found in the colder regions of North America, specifically in Canada and the United States. These beetles thrive in habitats with low temperatures and have a wide distribution across their range.

Preferred Trees

The primary host trees for the Red Flat Bark Beetle are poplar trees, however, they can also be found on other tree species. Poplar trees are abundant in cold habitats and contribute to the beetles’ effective distribution. Some characteristics of these preferred trees include:

  • Poplar trees: Abundant in colder regions and provide a suitable habitat
  • Other tree species: May also host the beetles, but poplar trees remain their preference

Comparing Poplar to other tree species in relation to Red Flat Bark Beetle:

Tree Species Abundance in cold habitats Suitability for Red Flat Bark Beetle
Poplar High Preferred
Other trees Varies Can host, but less preferred

In summary, the Red Flat Bark Beetle is widely distributed across cold habitats in North America. They primarily inhabit poplar trees, but can also be found on other tree species.

Life Cycle and Survival Mechanisms

Larvae and Development

The red flat bark beetle goes through a complete metamorphosis involving four life stages: egg, larva, pupa, and adult. After hatching from the egg, the larva consumes dead wood from under the bark of trees. During its development, the larva typically goes through multiple molts.

Some characteristics of red flat bark beetle larvae include:

  • Small, white, and worm-like appearance
  • Typically found beneath the bark of trees
  • Presence of six small legs
  • Chew on dead wood for sustenance and growth

As an example, one of the trees commonly infested by these beetles is the spruce tree. The beetle’s galleries and red-brown boring dust are signs of spruce beetle attack.

Anti-Freeze Proteins and Deep Supercooling Ability

Red flat bark beetles have unique survival mechanisms to withstand freezing temperatures. They possess beneficial anti-freeze proteins and a deep supercooling ability, which prevent ice crystal formation within their cells.

These adaptations include:

  • Synthesis of xylomannan: A glycolipid that helps in vitrification (transition to a glass-like state), keeping water in the beetles’ body from freezing.
  • Production of anti-freeze proteins: Prevents ice formation by binding to ice crystals, slowing down their growth.

A comparison table of these two mechanisms:

Mechanism Function
Xylomannan Synthesis Promotes vitrification, prevents water freezing
Anti-Freeze Proteins Binds to ice crystals, slows down crystal growth

These characteristics allow red flat bark beetles to survive extreme cold and continue their life cycle in harsh environments.

Identification and Key Features

Distinguishing Colors and Attributes

The Red Flat Bark Beetle is characterized by its distinct colors and attributes:

  • Red color: The beetle’s body has a bright red hue
  • Black antenna: Its antenna are black and segmented
  • Yellow legs: The beetle’s legs are yellow in color
  • Reddish elytra: The hardened forewings, or elytra, are reddish with a flat appearance

These features make Red Flat Bark Beetles easy to identify among other species.

Common Confusions and Misidentifications

It’s important to know the differences between the Red Flat Bark Beetle and other similar insects to avoid confusion. The following table compares the Red Flat Bark Beetle with other beetles that might be mistaken for it:

Feature Red Flat Bark Beetle Similar Beetle 1 Similar Beetle 2
Body color Red Yellow Brown
Antenna color Black Brown Black
Leg color Yellow Black Yellow
Elytra color Reddish Greenish Dark brown

By using this table as a reference, you can more accurately identify the Red Flat Bark Beetle and avoid misidentification.

Interactions with Other Species

Natural Predators

The red flat bark beetle (Cucujus clavipes), like other beetles, faces threats from various natural predators. These enemies often target beetle larvae and pupae, while some hunt adult beetles. Some examples of natural predators include:

  • Birds, such as woodpeckers
  • Mammals, such as bats
  • Insects, like other beetles and predatory wasps

Commensalism: Mites and Beetles

Beetles often form commensal relationships with mites. In these interactions, mites are known to hitch a ride on the beetles, using the beetles’ mobility to reach new locations. These mite species generally do not cause harm to the beetles, and in some cases, they may even benefit their beetle hosts by preying on other organisms that could threaten the beetles.

Comparison Table: Red Flat Bark Beetle and Mites

Feature Red Flat Bark Beetle Mites
Size 3-15 mm 0.1-1 mm
Habitat Bark of dead trees Various, including bark
Relationship with other species Predators or commensalism partners Commensal associations with beetles and other insects

Conservation and Ecological Importance

The Red Flat Bark Beetle plays a vital role in forest ecosystems. They contribute to sustainability by breaking down dead trees, facilitating the recycling of nutrients back into the soil.

In some cases, Red Flat Bark Beetles even have a symbiotic relationship with certain tree-dwelling fungi. The beetles carry fungal spores, which help them colonize and decompose dead wood, while the fungi provide a food source for beetle larvae.

  • Sustainability: Promotes decomposition and recycling of nutrients
  • Ecosystem: Participates in the forest carbon cycle
  • Symbiosis: Mutual relationship with certain fungi species

Beetle outbreaks can also have a thinning effect on forests, particularly during times of stress. This outcome can create healthier forest stands and reduce the intensity of wildfires over time.

However, when populations grow too large, Red Flat Bark Beetles may attack healthy trees and cause adverse effects on the ecosystem. Managing beetle populations through monitoring and timely intervention is crucial for maintaining a healthy balance.

Pros Cons
Promotes decomposition and nutrient cycling Can cause tree mortality if unmanaged
Thins forests under stress Potentially destructive to healthy trees
Reduces wildfire risk Dependent on monitoring and intervention

Understanding the ecological importance of Red Flat Bark Beetles can inform conservation efforts and contribute to the overall health and balance of forest ecosystems.

Further Information and Resources

Images and Online Guides

For detailed images and identification of Red Flat Bark Beetle (Cucujus clavipes puniceus) subspecies within the classification, there are informative online guides and resources available. These can help both entomologists and naturalists to better understand this beetle species. Some websites to explore include:

  • Insect Identification: Provides images and guidelines for recognizing various insects, including the Red Flat Bark Beetle.
  • Offers photographs and identification tips for beetles and other insects, as well as a community forum for discussing related topics.

Research and Analysis by Entomologists

Research and analysis conducted by entomologists can contribute to further understanding the Red Flat Bark Beetle, its subspecies, behavior, and habitat. In-depth studies and publications may provide valuable insights and data to enhance knowledge about this species. Some examples include:

  • Comparative studies on various subspecies within the Red Flat Bark Beetle classification.
  • Analysis of different habitats and their impact on the beetle’s distribution and population.
  • Research on the Red Flat Bark Beetle’s role in ecosystems, including its interactions with other species and potential benefits to the environment.
Comparison Points Red Flat Bark Beetle Other Bark Beetles
Habitat Under loose bark Usually attack living trees
Size 10-20mm Varies by species
Color Bright red or orange Often dark brown or black
Larval Development Highly adaptive Varies by species

When studying Red Flat Bark Beetles and related species, consider the following:

  • Observe changes in distribution, diet, and habitat preferences among various subspecies.
  • Examine potential threats or benefits to the environment and ecosystems from their presence.

In summary, resources such as images, online guides, and research by entomologists can significantly contribute to a comprehensive understanding of the Red Flat Bark Beetle and its classification.

Reader Emails

Over the years, our website, 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 Flat Bark Beetle


Look at what my cats found
July 13, 2010
They were getting along so I knew something was up. They found this running accross the carpet in my bedroom. First time I’ve seen more than a fly inside the house. The weather outside has been really hot the last couple of days, is that related?
Thanks, Devan
Colorado Foothills (suburbia)

Red Flat Bark Beetle

Hi Devan,
Your photo is blurry which often makes identifications difficult, but we are relatively certain that this is a Pole Borer,
Neandra brunnea, one of the Long Horned Borer Beetles in the family Cerambycidae.  According to BugGuide:  “Larvae bore in trees, as well as structural wood (such as poles, crossties) in contact with moist ground. Adults frequently come to lights, though sometimes adults emerge, mate, and lay eggs in the same cavity they occupied as a larva“.

Correction courtesy of Eric Eaton
It is Cucujus clavipes.

Thanks Eric,
According to BugGuide, the Red Flat Bark Beetle,
Cucujus clavipes, is “Found under the bark of ash and poplar, especially recently felled trees” and is “presumably predaceous on other arthropods.

Hi Daniel,
Sorry about the camera but I can say that the pictures on that link look exactly like what I have in front of me.  You rock!

Letter 2 – Red Flat Bark Beetle


Subject:  Red beetle
Geographic location of the bug:  Foothills of Western Cascades in Washington
Date: 04/26/2018
Time: 09:25 PM EDT
Your letter to the bugman:  Saw this on our deck… Can’t recall seeing a red beetle in our area before. What’s that bug?
How you want your letter signed:  Anonymous

Red Flat Bark Beetle

Dear Anonymous,
This is a Red Flat Bark Beetle,
Cucujus clavipes, and according to the Pennsylvania State University site:  “The flat bark beetle is found in forested habitats of northern North America (Alaska, Canada, and many northern and central U.S. states). … Adults are typically found under the bark in living or freshly cut trees although they might also be present in old logs and even in the leaf litter around fallen or cut trees. Tree species that seem to be preferred by the flat bark beetle include poplars, ashes, and oaks, but they are also found in a wide range of other species of trees. The adult flat bark beetles are active predators within their constricted, sub-bark micro-habitat.”

Letter 3 – Red Flat Bark Beetle


Subject: Cucujus clavipes
Location: Wellington, Colorado
September 22, 2012 10:48 pm
I decided to do some bug searching with one of my three sons today and it ended being all four of us. We have an old cottonwood stump that I cut down and we decided to pull away some of the bark to see what was going on. Upon pulling it off and getting past the centipedes, we saw two very unique beetles. One I was able to identify using bug guide!
So I’m submitting my pictures as I haven’t seen them on What’s that bug for a while.
Signature: Fish Seal

Flat Red Bark Beetles

Dear Fish Seal,
Thanks for submitting your images of Red Flat Bark Beetles,
Cucujus clavipes.  We have not posted a new image of the species since 2010.  The Florida State Collection of Arthropods has some additional information on the family.  It seems like your images were reduced in size and resolution.  We can easily accept images with a higher resolution in order to provide the highest quality for our readership.

Flat Red Bark Beetle

I’m sorry about how the pictures came through.  I have attached the full pictures.

Thanks.  We are making a swap, but that takes additional time.  Please submit full size files in the future.


Letter 4 – Flat Bark Beetle


Bugman here they come!
I’ve got a few pics of some bugs I haven’t been able to identify. Have fun! I look forward to seeing what you come up with. If you need better res images I can send them. … (Bug 2-1 & Bug 2-2) I found this bug chopping wood out behind my house in the bark of a Red Oak. Based on the face and body shape I’m guessing this is some kind of borer, but I was amazed by the the sharp red color. … I’ve got a lot more and am going to be putting up a nature notebook of all my findings from SW Michigan and my "world" travels. Thanks!
Dave Williams
St. Joseph, MI, USA

Hi Dave,
In the future, please just send one identification request per letter. This is a Flat Bark Beetle. It is not a borer beetle, but is in the family Cucujidae. The bright red adults and larvae live under the bark of dead trees where they eat small arthropods.

Letter 5 – Flat Bark Beetle: Cucujus clavipes


red bug
Hi Bugman,
I found this little red guy in some firewood, between the wood and the bark. It’s about the size and shape of a firefly but is a deep magenta color with a little black spot at the posterior and is flatter. Any ideas?

Hi Galen,
This is a Flat Bark Beetle, Cucujus clavipes. These beetles are well adapted for living under loose but close fitting bark. Both adults and larvae feed on insects. Cucujus clavipes is one of the largest and most brilliantly colored species in the family. It is especially common under the bark of freshly felled poplar and ash trees.

Letter 6 – Red Flat Bark Beetle


Flat Bark Beetle?
I found this guy crawling around my bedroom carpet today, and scolded him because he is most certainly not a carpet beetle! Is he a flat bark beetle? Don’t worry, after I took a picture of him in the jar, I let him go on a tree.

Hi Elizabeth,
Nice job identifying your Red Flat Bark Beetle, Cucujus clavipes. They are often found beneath the bark of felled ash and poplar trees where they hunt for small arthropods.

Letter 7 – Red Flat Bark Beetle


Subject: Unknown Bug at Yale BC
Location: Yale, BC
April 18, 2015 9:10 pm
My friend sent me this photo of a scarlet bug on his fire pit at Yale, BC but I have been unable answer his question as to what it is. I am sure I have seen it myself many years ago, but have not been able to find reference to it on the internet.
Signature: James

Red Flat Bark Beetle
Red Flat Bark Beetle

Dear James,
This looks like a Red Flat Bark Beetle,
Cucujus clavipes, and we suspect is was living on some wood your friend was going to burn in the fire pit.  According to Your Piece of the Planet:  “The Red Flat Bark Beetle, Cucujus clavipes, is typically found under the bark of ash and poplar.  Its flat shape allows it to easily move around under bark, and sometimes even into the tunnels of destructive wood borers and bark beetles, which it likes to eat.  This is beneficial, as it helps limit wood borer and bark beetle damage to the tree.”

Letter 8 – Red Flat Bark Beetle


Subject:  Whats this bug
Geographic location of the bug:  Pennsylvania
Date: 06/13/2019
Time: 09:42 AM EDT
Your letter to the bugman:  Can u help me identify this bug on a ash tree
How you want your letter signed:  Ryan

Red Flat Bark Beetle

Dear Ryan,
This is a beneficial Red Flat Bark Beetle, and according to BugGuide the habitat is “under loose bark of deciduous trees” and they eat “presumably predaceous on other arthropods.”


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. 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.

4 thoughts on “Red Flat Bark Beetle: Essential Facts and Tips”

  1. I have found two of an insect i’ve never seen before in my house. At first appearance, they look like small pieces of bark, not insects.. They move as if leaves rustling by wind. They are wingless but may have very short legs. They could also be mistaken for small rocks. Their colors are black, brown, white and grey. When encountered, they cease all movement. After a while, a tube like mouth part appears. They seem not to have eyes. They appear to be shaped like a squash seed and about 1/2 inch long. In appearance, they do not look like insects but rather like plant material, and they especially look like some sort of seed. But they move! I live in central Florida, out in the country. I can not find anything like them listed under Florida insects. Any idea what these creatures could be? Thanks!


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