Spider Beetle or Bed Bug? Identifying and Managing Common Home Invaders

folder_openHemiptera, Insecta
comment3 Comments

We know you’re dealing with pests invading your space, potentially putting health and property at risk. If you need help identifying and eliminating the infestation at the source, connect with our recommended local professional near you.

Spider beetles and bed bugs are two distinct insect species that are often mistaken for one another due to their similar size and appearance. 

This confusion can lead to misinformed decisions regarding pest control and prevention. 

It’s crucial to differentiate between the two, as their behavior, habitats, and treatment methods vary significantly. 

Proper identification ensures effective management and reduces the risk of unnecessary interventions or treatments.

In this article, we will look at how to differentiate between these two bugs and the proper treatment methods for them.

Spider Beetle vs Bed Bug: Physical Appearance

Spider Beetles

Spider beetles are easily distinguishable by their oval-shaped bodies and distinct hunch-backed appearance. 

While their shape is reminiscent of a small bean or pea, it’s their hunched posture that sets them apart from bed bugs. 

This hunch-backed feature gives them a more rounded appearance when compared to bed bugs.

Their thin, spindly legs give them the appearance of a spider, which is where there name comes from.

Bed Bugs

Bed bugs also sport an oval shape, but their bodies are notably flat, resembling the size and shape of apple seeds. 

This flatness allows them to easily hide in crevices and cracks, making them adept at concealing themselves in various environments. 

Diet and Feeding Habits

Spider Beetles

Spider beetles are opportunistic foragers known for their diverse diet. 

Common food sources for spider beetles include silk, wheat, rye bread, seeds, ginger, almonds, beans, and flour

Their ability to feed on such a variety of items sets them apart from bed bugs, which have a much more specialized diet.

Spider Beetle vs Bed Bug

Bed Bugs

In stark contrast, bed bugs are obligate blood feeders, meaning they exclusively feed on blood. 

While there are over 90 species of bed bugs, only three are known to feed on humans. 

Bed bugs are nocturnal in their feeding habits, preferring to bite their hosts at night while they sleep

During feeding, they inject an anesthetic to numb the area, allowing them to feed without detection. 

This anesthetic injection is responsible for the delayed pain and itchiness associated with bed bug bites. 

Bed bugs’ reliance on blood and their mode of feeding is a fundamental difference when compared to spider beetles.

Scientific Classification

Spider Beetles

Spider beetles belong to the subfamily Ptininae within the family Ptinidae. 

This subfamily is quite diverse, comprising about 70 genera and approximately 600 species. 

Bed Bugs

Bed bugs fall under the family Cimicidae, a family primarily composed of blood-feeding insects. 

Within this family, two species are of particular significance concerning human infestations: Cimex lectularius, commonly known as the common bed bug, and Cimex hemipterus, known as the tropical bed bug. 

These two species are the primary culprits responsible for bed bug infestations in human habitats and are the focus of pest control efforts.

Bed Bug

Size and Growth

Spider Beetles

The adult size of spider beetles typically falls within a range of 1.5mm to 3.5mm in length (approximately 0.06 to 0.14 inches). 

This size range may vary slightly among different species within the spider beetle family.

Bed Bugs

Adult bed bugs are slightly larger than spider beetles, with a size range of approximately 5mm to 7mm in length (about 0.19 to 0.27 inches). 

Bed bugs are noticeably larger than spider beetles. This difference in size, with bed bugs being roughly three to five times larger is an easy way to distinguish between the two insects.

Reproduction and Lifecycle

Spider Beetles

Spider beetles have a relatively longer gestation period. The time it takes for their eggs to hatch typically falls in the range of 3 to 4 weeks. 

Bed Bugs

In contrast, bed bugs have a shorter gestation period. Their eggs usually hatch within a span of 1 to 2 weeks. 

This shorter period can lead to infestations growing quickly if not addressed promptly.

Habitats and Distribution

Spider Beetles

Spider beetles are commonly found in various regions, including North America. They are particularly prevalent in environments that offer access to food sources. 

Typical habitats for spider beetles include food storage areas such as pantries, warehouses, and kitchens. 

Bed Bugs

Bed bugs have a global distribution and can be found in nearly every part of the world. 

They are known for their preference for habitats close to their hosts. As a result, common bed bug habitats are often associated with human living spaces. 

They are frequently found in mattresses, upholstered furniture, bed frames, and other areas close to where humans sleep or rest. 

Bed Bug

Spider Beetle Bites Vs Bed Bug Bites

Spider Beetle Bites

  • Frequency: Bites from spider beetles are relatively rare, and these insects are not known to commonly bite humans.
  • Appearance and Symptoms: When spider beetle bites do occur, they typically result in mild symptoms. The bites may appear as small, red, itchy bumps on the skin. However, it’s important to note that many people may not even notice or react to spider beetle bites.
  • Duration and Treatment: Spider beetle bites, if they occur, tend to resolve on their own within a short period. Treatment is usually not necessary, as the symptoms are mild and self-limiting. However, if discomfort persists, over-the-counter itch relief creams can be used.

Bed Bug Bites

  • Frequency: Bed bug bites are more common and frequently encountered when there is a bed bug infestation in a living space.
  • Appearance: Bed bug bites often appear in a line or cluster on the skin. They are characterized by redness and itchiness, and they can be quite distinctive in appearance.
  • Symptoms: In addition to itching and redness, bed bug bites may lead to swelling. Some individuals may experience more severe reactions or allergic responses to bed bug bites.
  • Duration and Treatment: Bed bug bites can last for several days to a couple of weeks, depending on an individual’s sensitivity. While treatment typically focuses on relieving itching and discomfort with over-the-counter creams or antihistamines, it’s essential to address the underlying bed bug infestation through professional pest control services.

Call for pest control services now.

Treatment and Prevention

Spider Beetles

  • Prevention Tips: Preventing spider beetle infestations primarily involves maintaining good sanitation practices in food storage areas. Key prevention tips include:
    • Regularly vacuuming and cleaning food storage spaces.
    • Inspecting kitchen pantries for signs of infestation and removing contaminated items.
    • Sealing cracks, gaps, and holes in the building to prevent entry.
  • Chemical Treatments: In the event of a spider beetle infestation, chemical treatments can be effective. Professional pest control services can apply appropriate insecticides to eradicate the infestation.
Spider Beetle

Bed Bugs

  • Heat Treatment: Heat treatments involve raising the temperature of infested areas to levels that bed bugs cannot survive. This is often done using specialized equipment and is highly effective.
  • Cold Treatment: Cold treatments involve using freezing temperatures to kill bed bugs and their eggs. This method may be employed in specific situations.
  • Chemical Treatment: Insecticides are commonly used to treat bed bug infestations. Professional pest control services can apply these chemicals to affected areas. It’s important to use registered pesticides and follow safety guidelines.

Bug Control Recommendation Tool

What type of pest are you dealing with?

How severe is the infestation?

Do you require child/pet/garden safe treatments (organic)?

Are you willing to monitor and maintain the treatment yourself?


While spider beetles and bed bugs are distinct insects with many differences, there are some notable similarities between them:

Nocturnal Behavior

Both spider beetles and bed bugs are primarily active during the nighttime hours. 

They tend to hide during the day and emerge at night to search for food or to feed on their hosts (in the case of bed bugs). 

This nocturnal behavior is a common trait shared by these two pests.

Rapid Infestation

Both spider beetles and bed bugs have the potential for rapid infestation under suitable conditions. 

Spider beetles, with their diverse diet, can quickly multiply and infest food storage areas, rendering stored items inedible. 

Bed bugs, due to their reproductive rates, can establish infestations that grow in size if not addressed promptly. 

Both pests have the capability to become significant nuisances when left unchecked.

Bed Bug


In summary, spider beetles are foragers with diverse diets, while bed bugs exclusively feed on blood. 

Their differing sizes, gestation periods, and habitats make them distinguishable. 

Additionally, we discussed the rare instances of spider beetle bites, contrasting them with common bed bug bites known for their red, itchy clusters. 

Both insects share nocturnal habits and are capable of rapid infestations. 

Understanding these differences and similarities between the two is essential for pest management and prevention.

Call for pest control services now.

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 – Bed Bug


Subject: Help!!!
Location: Monroe Mi
August 7, 2015 8:54 pm
it is currently 11:50 in the good ole state of Michigan right now, and as I was laying in bed about 10 minutes ago I felt something crawling on my arm. My first thought when I seen the little thing was that it was a sick, however I don’t believe it is. Can someone help me identify this little bugger?
Signature: laura

Bed Bug
Bed Bug

Dear Laura,
This is a Bed Bug and you should immediately investigate to determine if this is an isolated individual or a possible infestation.

Letter 2 – Bed Bug


Subject: ?? what the!?
Location: northeast u.s.
August 22, 2015 3:02 pm
I live close to buffalo. NY. Find these guys occasionally crawling on me. Have had a skin rash that has diagnosed as hives. I think these may have something to do with it. Happen to find them on my skin while sitting on my couch. Explode with blood when If I crush em!
Signature: sean

Bed Bug
Bed Bug

Dear Sean,
This is a Bed Bug.  Is this a recently acquired second hand couch?  Have you had recent house guests staying on the couch?  You need to deal with this problem before you have a full scale infestation on your hands.

Letter 3 – Bed Bug


Subject: what is it
Location: New Hampshire/ Manchester
October 3, 2015 12:08 am
Just want to know if it’s a stupid little flee or a freaking bed bug
Signature: Darrick

Bed Bug
Bed Bug

Dear Darrick,
This sure looks like a Bed Bug to us.

Letter 4 – Bed Bug


Subject: What is this
Location: Hoboken nj
October 4, 2015 12:34 pm
Found two of these on separate dates in our home in Hoboken
Was approx. one quarter inch big
Would love your help!
Signature: AP

Bed Bug
Bed Bug

Dear AP,
Alas, this is a Bed Bug, and if you found two, chances are good there are more.  You should take immediate steps to eliminate them before you have an infestation on your hands.

Letter 5 – Bed Bug


Subject: Tick or Mite
Location: Jacksonville,AR USA
October 27, 2015 8:56 pm
I keep finding these in my house everywhere in the bathroom living room and even our clothes. We have one cat and that’s it he occasionally goes outside but not for very long. Please help.
Signature: Joseph Ederington

Bed Bug
Bed Bug

Dear Joseph,
You have Bed Bugs.  You should probably seek professional assistance in their eradication.

Letter 6 – Bed Bug


Subject: Is this a bed bug?
Location: Augusta georgia
November 15, 2015 3:48 pm
Found this on my bed scared it may be a bed bug. Can you guys help?
Signature: Concerned parent

Bed Bug
Bed Bug

Dear Concerned Parent,
This is a Bed Bug, and if there is one, there are likely more.  You should take immediate steps to eliminate the problem.  Though Bed Bugs are blood suckers that feed while folks are sleeping, they are not vectors for spreading diseases.

Thank you!! exterminator is coming out on Wednesday to do an assessment

Letter 7 – Bed Bug


Subject: strange bug
Location: Hanceville, Alabama
November 28, 2015 8:17 pm
We found this in our bed!?!?!?
Signature: diana

Bed Bug
Bed Bug

Dear Diana,
This is a Bed Bug.  The bad news is that they will suck the blood of sleeping humans and if you found one, there are likely more.  The good news is that Bed Bugs do not spread diseases.

Letter 8 – Bed Bug


Subject: What type of bug is this
Location: Pennsylvania
December 17, 2015 12:00 pm
I found this bug crawling on me today and i squished it and red blood came out. I’m not sure what type of bug this is i think it’s a bed bug and i need to know asap. Can u please help me identify it
Signature: Thank you rose

Bed Bug
Bed Bug

Dear Rose,
We are sorry to have to inform you that this is a Bed Bug.  This posting will go live while we are away from the office for the holidays.


  • 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.

    View all posts
  • 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.

    View all posts
Tags: Bed Bug

Related Posts

3 Comments. Leave new

Leave a Reply

Your email address will not be published. Required fields are marked *

Fill out this field
Fill out this field
Please enter a valid email address.
You need to agree with the terms to proceed