Spider Beetle: All You Need to Know – Your Friendly Guide

Spider beetles are a curious group of insects that can pique your interest due to their distinctive appearance and behavior. With their long legs and oval or cylindrical bodies, they share a superficial resemblance to spiders, which gives them their common name 1. Ranging in size between 2 to 5 millimeters, these tiny beetles can … Read more

Spider Beetle Life Cycle: A Closer Look at These Intriguing Insects

Spider beetles are fascinating creatures that often go unnoticed in the world of insects. They thrive in various environments, and their unique life cycle sets them apart from other beetles. Understanding the spider beetle life cycle can provide valuable insights into their behavior and ecological roles.

The life cycle of spider beetles consists of several stages, starting from the egg and developing into a full-grown adult. During this process, you’ll notice that both the adult and the grub-like larval stage are scavengers. They feed on a variety of materials, such as broken grain, seeds, dried fruits, and even wool and feathers source.

As a curious observer, gaining knowledge of the spider beetle life cycle gives you a greater appreciation for these small yet complex insects. Keep an eye out for them as you explore various habitats and environments; you might be surprised at how much you can learn from them.

Spider Beetle Overview

Spider beetles are fascinating insects belonging to the family Ptinidae. You might mistake them for spiders initially, but they are actually part of the beetle order, Coleoptera. There are several genera of spider beetles, including Mezium and Gibbium psylloides, and they can be found across the world.

These beetles often have long, slender legs and antennae, giving them their name due to their superficial resemblance with spiders. Their body size generally ranges from 2 to 5 millimeters, with colors varying from light brown to dark reddish-brown.

Some notable features of spider beetles include:

  • Oval or cylindrical bodies
  • Long, skinny legs
  • Antennae covered in pale yellow to cream-colored hairs
  • Diverse species within the Ptinidae family
  • Presence in various habitats worldwide

Spider beetles undergo a lifecycle that consists of eggs, larval stage, pupal stage, and adulthood. Both adult and larval spider beetles are scavengers, feeding on a variety of organic materials.

In comparison to other beetles, spider beetles are relatively less known, but their unique appearance and diverse species make them an interesting study focus for enthusiasts and researchers alike. So next time you encounter a spider beetle, take a moment to appreciate the small details that make them distinctive members of the beetle world.

Identifying Spider Beetles


Spider beetles have a unique appearance, with their oval or cylindrical body shape and long, thin legs. Their color can vary between different shades of brown, black, yellow, and gold. They may resemble spiders due to their long legs and round bodies.


Spider beetles are usually quite small, ranging from 2 to 5 millimeters in length. These tiny insects may be hard to spot with the naked eye, but their distinctive appearance can help you identify them.

Comparative Description

When comparing spider beetles to other insects, you might notice some similarities with spiders such as their long legs and a similar body shape. However, spider beetles have six legs as opposed to the eight legs of spiders.

Distinct Characteristics

Some of the unique features of spider beetles include:

  • Cylindrical or oval-shaped body
  • Elytra (hardened wing covers) that may be shiny or dull
  • Long, thin legs that give them a spider-like appearance
  • Various color patterns, such as reddish-brown, black, yellow, or gold


Spider beetles have a cosmopolitan distribution and can be found across North America, Australia, and other parts of the world. They are known to infest stored products, warehouses, museums, homes, and other environments where food storage is present.

Prominent Species

The American spider beetle (Mezium americanum) is a common species of spider beetle found in North America. They are reddish-brown to black in color, with a shiny, globular abdomen, and can be recognized by their pale yellow to cream-colored hairs covering their head, thorax, legs, and antennae.


You can find spider beetles in various environments, typically where food storage occurs. They tend to dwell in cracks, shelves, and storage areas in homes, warehouses, or museums. Keep an eye out for these insects in places with stored products, as they are known to infest such areas.

Spider Beetle Life Cycle


Spider beetles begin their life cycle as tiny eggs. Females of some species cover their eggs with materials like remnants of their meal to protect them. The eggs typically take around 7 to 10 days to hatch.

Larval Stage

After hatching, the spider beetles enter their larval stage. During this stage, they appear as white or pale yellowish grub-like creatures. They scavenge for food, helping them grow and prepare for the next phase of their life cycle.

Pupal Stage

As spider beetles reach the end of their larval stage, they form a cocoon and enter the pupal stage. Inside the cocoon, the larvae undergo a complete metamorphosis, transforming into adult spider beetles.

Adult Stage

Once the metamorphosis is complete, the adults emerge from their cocoons. Adult spider beetles are generally small, ranging between 2 to 5 millimeters long, and can be dark brown or light brown in color. They have long legs, which gives them a superficial resemblance to spiders.

In the adult stage, spider beetles continue to scavenge for food and mate. After mating, the females lay eggs, and the cycle begins again.

Optimum Conditions for Growth

To ensure successful development from egg to adult, spider beetles require specific conditions. This can include factors such as:

  • Humidity: High levels of humidity are crucial for the hatching of spider beetle eggs.
  • Temperature: A moderate temperature range is essential for the beetles’ growth and reproduction.
  • Food sources: As scavengers, spider beetles need access to materials like dried plants, grains, and other organic debris.

By providing the proper environment, you can help support the healthy growth of spider beetle populations.

Spider Beetle Diet

Spider beetles have a diverse diet that varies depending on the species and their environment. They can be found in a variety of locations such as households, warehouses, and other areas where food is stored.

Their primary food sources include:

  • Stored foods: Spider beetles are known to be pests that infest stored food products. They have a preference for grain-based items, but they can also consume other types of food.
  • Seeds: These beetles enjoy consuming different types of seeds, which are abundant in various food storage environments.
  • Dried fruits: Dried fruits like raisins and dates are also part of a spider beetle’s diet.

Other food sources they might consume are:

  • Grains: Bowls of rice, flour, and other grains are attractive to spider beetles. They can infest these items and make them unfit for human consumption.
  • Dead insects: Some species of spider beetles feed on dead insects, making them a form of natural pest control.
  • Spices: They are also known to infest spices, affecting their flavor and quality.

As scavengers, they can consume a variety of animal by-products:

  • Wool and feathers: Spider beetles sometimes eat wool and feathers, which can be found in clothing and bedding materials.
  • Animal remains: In some cases, spider beetles can feed on animal remains like carcasses and bones.

To sum up, spider beetles are adaptable feeders that can consume a wide variety of food items. Their diet is mainly based on stored foods, seeds, and dried fruits; however, they can also eat grains, dead insects, spices, and various animal by-products. It’s important to be aware of their dietary preferences to prevent infestations and protect your stored food supplies.

Spider Beetles as Pests


Spider beetles are common and widespread insects that can infest homes and businesses as stored product pests. They are most frequently found in pantries, storage areas, and warehouses where they feed on a variety of stored food products. Some common examples of products they infest include cereals, grains, dried fruits, and even non-food items like pet feed and stored textiles. As a result, they can be a source of household pests and may even contaminate your stored items.

Damage Caused

When spider beetles infest your stored products, they can cause various types of damage. Their feeding habits may lead to:

  • Contamination: When these pests infest food items, they can leave behind feces and body parts, contaminating the product and making it unfit for consumption.
  • Piercing: Spider beetles, like the biscuit beetle, may create tiny holes in packaging materials as they chew through to reach their preferred food source.
  • Food spoilage: As they feed on your stored items, they may facilitate the growth of mold and other pathogens that can lead to spoilage.

Conducive Conditions for Infestation

Understanding the factors that contribute to spider beetle infestations can help you better manage these pests in your home or business. Some conditions that determine the likelihood of infestations are:

  • Temperature: Spider beetles thrive in temperatures between 65°F to 80°F (18°C to 27°C) and prefer dark areas with moderate to high humidity levels.
  • Food sources: Abundant food sources like stored grains and dried fruits can attract spider beetles to your home or storage facility.

In summary, be cautious of spider beetles as pests due to their infestation habits, the damage they can cause to stored products, and the conditions that favor their presence. Addressing these factors through proper storage techniques and pest management can help keep these insects at bay and protect your stored items.

Handling Spider Beetle Infestations

To control a spider beetle infestation, start by thoroughly cleaning the infested area. Remove any clutter and wipe down surfaces to eliminate potential food sources and hiding spots for these pests. Vacuum all corners, cracks, and crevices as this will help to remove eggs, larvae, and adult beetles from the environment.

  • Control: Implement preventative measures such as properly sealing and storing food items, disposing of trash regularly, and maintaining a clean and clutter-free living space.
  • Cleaning: Regularly clean areas where you have found spider beetles, paying particular attention to floors, shelves, and corners.
  • Vacuum: Use a vacuum cleaner with a strong suction to remove spider beetles from carpets, furniture, and other surfaces where they may be hiding.
  • Airtight containers: Store your dry goods, such as grains, cereals, and pet food, in airtight containers to prevent spider beetle infestations.

In addition to these steps, consider using natural methods to combat spider beetles. Introduce beneficial insects such as predatory mites or rove beetles in your garden to help keep spider beetle populations under control.

Here are the pros and cons of using natural control methods:

Pros Cons
Environmentally friendly May take longer to see results
Non-toxic to humans and pets Requires careful monitoring
Targets only specific pest populations Effectiveness can vary depending on factors

Remember, maintaining a clean and well-organized living space is key in preventing spider beetle infestations. By following these tips and staying vigilant, you can effectively manage and control spider beetle populations in your home.

Biological Classification

Spider beetles belong to the Animalia kingdom, as they are multicellular organisms that consume other organisms for sustenance. Like other insects, they are part of the Arthropoda phylum, which consists of invertebrates with exoskeletons, segmented bodies, and jointed appendages.

In particular, spider beetles are under the Insecta class, characterized by having three body segments, a pair of antennae, and three pairs of legs. Spider beetles earned their name because of their superficial resemblance to spiders, with long legs and oval or cylindrical bodies.

Here is a brief comparison of the three main taxonomic groups:

Taxonomic Group Characteristics Examples
Animalia Multicellular, heterotrophic organisms Mammals, Birds
Arthropoda Invertebrates, exoskeletons, segmented bodies Insects, Spiders
Insecta Three body segments, antennae, three pairs of legs Beetles, Flies

To recap, spider beetles are part of the Animalia kingdom, Arthropoda phylum, and Insecta class. This gives them features such as being multicellular, having exoskeletons, and sporting segmented bodies. Thus, they exhibit the long legs and distinct body shape reminiscent of spiders while actually being classified as beetles.

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 – Spider Beetles


Apartment Bug – Manhattan NYC
April 12, 2010
Hi Thanks for your help! I live in a newly renovated apartment in Manhattan, New York and keep coming across these bugs. (image attached). I am concerned that they might be ticks or bed bugs? I usually find them crawling the walls, but found a bunch in a light fixture. Any help identifying them or any risk they may pose? Thanks so much!
Bob from NYC
West Harlem, New York, NY

Spider Beetles

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Desert Spider Beetle: Your Quick Guide to These Fascinating Insects

The Desert Spider Beetle is an intriguing creature found in arid environments. This fascinating arthropod is part of the spider beetle family, which has several species known for infesting stored products. Although they share similarities with spiders, spider beetles primarily differ in their oval or cylindrical shape, long legs, and brown color ^(source)^.

These beetles have an array of characteristics that make them well-adapted for survival in their harsh habitats. For instance, their small size – ranging from two to five millimeters in length – enables them to navigate complex environments with ease. Additionally, they generally feed on organic debris and decaying matter, making it easier for them to find nourishment in their surroundings ^(source)^.

Desert Spider Beetle Overview

Family and Genera

Desert Spider Beetle belongs to the family Meloidae and the genus Cysteodemus. Their unique characteristics include:

  • Generally two to five mm long
  • Oval or cylindrical body shape
  • Long-legged and brown in color

Cysteodemus Armatus

Cysteodemus Armatus, also known as the Desert Spider Beetle, is a species native to arid regions. Some features of this species are:

  • Superficial resemblance to spiders
  • Active at night, hiding during the day
  • Attracted to lights
Feature Desert Spider Beetle Spider
Body Shape Oval or cylindrical Elongated
Legs Long and slender Long and hairy
Size 2 to 5 mm Larger than beetles

In summary, Desert Spider Beetles are small, yet fascinating insects native to arid environments. They have unique characteristics that set them apart from spiders and other beetle species.

Habitat and Distribution

California and Mojave National Preserve

The Desert Spider Beetle is found in California, USA, specifically in the Mojave National Preserve.

This region is known for its unique flora and fauna, making it an ideal habitat for the beetle.

Cinder Cones Area

In the Cinder Cones Area, these beetles thrive due to the presence of:

  • Volcanic rock
  • Sandy soil
  • Various plant species

These factors allow the Desert Spider Beetle to find shelter, food, and areas for reproduction.

San Bernardino County

San Bernardino County in California is another region where the Desert Spider Beetle can be found.

The county’s diverse range of ecosystems create suitable conditions for the beetle’s survival.

Comparison Table

Habitat Conditions Advantages for Desert Spider Beetle
Mojave National Preserve Arid desert & unique vegetation Diverse food sources & shelter
Cinder Cones Area Volcanic rock & sandy soil Ideal ground for egg-laying
San Bernardino County Various ecosystems Multiple options for habitat

Beetle Features

  • Adapted for desert environment
  • Carnivorous diet
  • Efficient reproduction

Beetle Characteristics

  • Well-camouflaged
  • Stealthy hunter
  • Resilient in harsh conditions

Physical Characteristics and Behavior

Size and Appearance

Desert Spider Beetles are small insects with their size ranging from 2 to 5 mm long. They are oval or cylindrical, long-legged, and brown in color. Their appearance is often likened to spiders, which earned them their name 1.

  • Size: 2-5 mm long
  • Shape: Oval or cylindrical
  • Color: Brown
  • Legs: Long

Inflated Beetle

The Inflated Beetle is another name given to desert spider beetles due to their distinct appearance. This refers to the swollen abdomen and spindly legs, giving them a unique appearance compared to other beetles.

  • Swollen abdomen
  • Spindly legs


Desert Spider Beetles are flightless, which means they rely on crawling for movement. This trait, along with their small size and spider-like appearance, makes them excel at navigating their arid and hostile habitats.

  • Movement: Crawling
  • Environment: Arid habitats

Life Cycle and Diet


Desert Spider Beetles start their life as eggs. They remain in their egg form for about 7 to 10 days before hatching into larvae1.

Larva and Cocoon

Once hatched, the larva go through a grub-like stage where they are white and fleshy2. As the larva mature, they form a cocoon3.

Feeding Habits

Desert Spider Beetles feed on various items:

  • Grains
  • Seeds
  • Dried fruits
  • Spices
  • Dead insects
  • Rodent droppings4

Comparison between the larval and adult stage in terms of diet5:

Stage Diet Preferences
Larva Grains, seeds, dried fruits
Adult Spices, dead insects, droppings

Bullets for key features:

  • Egg stage: 7 to 10 days
  • Larva stage: Grub-like, white and fleshy
  • Cocoon stage: Transforming into adults
  • Diet: Grains, seeds, dried fruits, spices, dead insects, rodent droppings

Impact on Humans and Environment

Infestation and Pests

Desert Spider Beetles can cause infestations, becoming pests in some environments. They are attracted to certain plant species, which they feed on, causing damage to crops and landscapes. Effective pest control methods for Desert Spider Beetles are essential to prevent extensive damage to plants and vegetation. Examples of such methods include:

  • Biological control: using natural predators to keep beetle populations in check
  • Pesticides: applying chemical treatments specifically targeting beetles
  • Cultural practices: ensuring proper plant care and maintenance to reduce beetle-attracting factors

Dangerous or Harmful?

If you’re wondering whether Desert Spider Beetles pose a direct threat to humans, the answer is: not really. Despite their intimidating appearance, these insects are generally harmless to humans and are not venomous or aggressive. However, it is important to treat them with caution, as any unfamiliar insect could potentially have unexpected defensive reactions. Here’s a quick comparison of Desert Spider Beetles and dangerous spider species:

Attribute Desert Spider Beetle Dangerous Spider
Venomous No Yes
Aggressive No Possibly
Damaging to plants Yes No

In summary, Desert Spider Beetles pose a minimal threat to humans and the environment, primarily impacting plants they infest. By using effective pest control methods, their populations can be managed, and their impact mitigated.

Prevention and Control Methods

Identification and Inspection

Identifying a desert spider beetle is crucial for effective prevention and control. They are usually two to five mm long, oval or cylindrical, long-legged and brown. To inspect for their presence, look for:

  • Small holes in wooden structures
  • Fine, powdery frass near suspected infested areas

Possible prevention methods include:

  • Sealing cracks and crevices: Close off entry points where pests can hide.
  • Sanitation: Regularly clean and declutter your living areas; remove stacks of newspapers, magazines, and cardboard.

Professional Pest Control Services

For a more comprehensive approach, consider hiring a pest control professional. Benefits of pest control services include:

  • Expert identification and inspection abilities
  • Access to specialized equipment and treatment methods
  • Offering long-term solutions and prevention guidance
  • Handling potentially harmful chemicals safely

However, there are some drawbacks:

  • Can be expensive
  • May require multiple visits
  • Potential exposure to chemicals

Comparison Table: DIY vs Pest Control Services

DIY Prevention & Control Pest Control Services
Cost-effective Can be expensive
Addresses minor infestations Effective for severe infestations
Requires self-education and time Expert knowledge and solutions

To conclude, preventing desert spider beetle infestations can be done through proper identification, inspection, and a mix of DIY methods or professional pest control services.

Resources and Further Information

BugGuide and Naturalists

BugGuide is an excellent online resource for identifying and learning more about spider beetles and other insects. It offers:

  • Detailed photographs and descriptions
  • Information on habitats and behaviors

Joining a local group of naturalists can also help you expand your knowledge about desert spider beetles and other fauna in your area. They often organize field trips, workshops, and presentations to share information and expertise.

Local Extension Office and Expert Advice

Your local extension office can provide you with invaluable resources for understanding desert spider beetles. They can:

  • Offer expert advice and assistance
  • Give you access to up-to-date research and information

Contacting expert professionals in entomology and related fields can provide you with additional insights into desert spider beetles and their characteristics. These experts may be able to answer specific questions and share their research findings.

Resource Pros Cons
BugGuide Easy-to-use online resource May not cover all species
Naturalists Local knowledge and hands-on experience Membership may be required
Local Extension Office Personalized advice and assistance Limited to region
Expert Professionals Access to exclusive knowledge and research May be difficult to contact

In summary, a combination of online resources, local groups, and professional advice can provide you with a wealth of information on desert spider beetles and help you expand your understanding of these fascinating creatures.


  1. Spider Beetle | Horticulture and Home Pest News 2

  2. https://hortnews.extension.iastate.edu/spider-beetle

  3. https://extension.unh.edu/blog/2019/07/how-can-i-control-beetles-are-eating-my-garden

  4. https://hortnews.extension.iastate.edu/spider-beetle

  5. https://hortnews.extension.iastate.edu/spider-beetle

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 – Desert Spider Beetle


Desert Spider Beetle or Black Bladder-Bodied Meloid
June 20, 2010
I found some of these beetles in my garden and looked them up to see what they were. They are very pretty, however, I really need to know if they are going to do any damage to either my house our my plants. Thank you for your information.
Living in New Mexico
Central New Mexico

Desert Spider Beetle

Dear Denizen of New Mexico,
Your identification is correct.  this is a Desert Spider Beetle or Black Bladder Bodied Meloid, Cysteodemus wislizeni, which is profiled on BugGuide.  Adult Blister Beetles feed on plants, but we don’t know the preferred plant that this species prefers to feed upon.  The Sam Wells Entomology page does not indicate the food preferences.  We believe they probably feed on some desert annual species.  They will not harm your home.  Blister Beetles, of which the Desert Spider Beetle is one, are capable of causing a skin reaction if they are carelessly handled.

Letter 2 – Desert Spider Beetle


Location: Dripping Springs, New Mexico
April 17, 2012 1:34 pm
Sorry I couldn’t get a better photo of this vividly colored bug. It wouldn’t stop it’s frantic running.
Signature: Lynn

Desert Spider Beetle

Hi Lynn,
Desert Spider Beetles in the genus
Cysteodemus are also known as Inflated Beetles.  They are actually a genus of Blister Beetles, a curious family that has great diversity in the deserts of the southwest.  You may read more about Desert Spider Beetles on BugGuide.

Letter 3 – Desert Spider Beetle


I have found a yellow and black beetle in the desert
This is the only picture that i have of it.. the rest were all way to blurry as i was following it around with my camera trying to get a perfect shot..It is the first time I have ever seen anything like that.. I found it in the desert in 29 palms, ca. Oddly enough though after a few hours i spotted another one on the other side of the fence. it is a very pretty beetle.. and its very fast. Can you help me at all with identifing it?

he he he i have finally found it i looked for it through almost all the beetle pages… thanks tho!! maybe you can still feature the picture cause the clarity on it is amazing. how much detail my camera caught.. :] thanks

Hi Terra,
We are happy you located your Desert Spider Beetle, Cysteodemus armatus, also known as the Inflated Beetle, on our site without our help.

Letter 4 – Desert Spider Beetle


Can you tell what this bug is?
I found this colorful beetle in Phoenix, AZ outskirts in the desert. Do you know the species? Thanks.

This is definitely a Blister Beetle, and we are also certain it is the genus, Cysteodemus, the Desert Spider Beetles. One species is black and the other is white. The white species is the White Bladder-bodied Meloid, Cysteodemus armatus. We are perplexed by the yellow coloration and wonder if it is a variation, a chemical tinting, a pollen dusting, or a different species. We will inquire if Eric Eaton has an opinion.

Letter 5 – Desert Spider Beetle


Mystery SoCal Bug (not a jerusalem cricket!)
This is a shot I took back in March of 06. We found it on a herp trip to SoCal, it was in a canyon somewhere between Joshua Tree & the Salton Sea. It was about the size of a lima bean. I’m a biologist and I’ve never seen anything like it. It’s been bugging me for almost a year, help bugman! Cheers,
Brandon Fessler

Hey Brandon,
What a great photo of a Desert Spider Beetle in the genus Cysteodemus. This is probably Cysteodemus armatus which is found in California. Desert Spider Beetles are a group of Blister Beetles in the family Meloidae.

Letter 6 – Desert Spider Beetle


blue beetles in New Mexico
Hi bugman,
I just moved to Las Cruces NM from Australia. My husband, 6 week old puppy and I were walking in one of the local arroyos yesterday and we saw what we thought were jewels on the ground. Closer inspection revealed two beetles. One large and one small….roundish like a grape with brilliant iridescent blue spots on their backs. They moved very fast once we took an interest in them. As my husband held back the puppy I used his cell phone to attempt a picture. I am not use to his phone and the glare was pretty bad at that time of the afternoon so the photos were dismal..but this one sort of captures the larger beetle in flight from us. My husband has previously lived in this area for a number of years and has never come across these beetles. I have started a search through Google and your site (I am up to page 6 of the beetles) but as the 6 week old puppy keeps wanting attention I am a bit distracted from the task! I hope that you can help us with an identification.

Hi Kate,
Your photo is quite blurry, but we are nearly certain this is a type of Blister Beetle in the genus Cysteodemus known as the Desert Spider Beetles. There is one blurry photo on BugGuide that matches your image, and it is identified as Cysteodemus wislizeni.

Letter 7 – Desert Spider Beetle


Hello, What’s this bug?

A Desert Spider Beetle, Cysteodemus armatus.

Letter 8 – Desert Spider Beetle


Yellow and black bug
This was taken in the Mojave desert in SE CA (San Bernardino County) It was a fast moving bug about the size of a dime. I saw a similar bug in the desert of San Diego County but the insect was white in the place that this one is yellow. Both were crawling on the ground.

Hi Nancy,
This is a Desert Spider Beetle, a Blister Beetle in the genus Cysteodemus.

Letter 9 – Desert Spider Beetle


A Beetle Picture For You
Howdy! I was out and about some weeks ago and caught on camera this fabulous shiny beetle. I immediately tried finding out what it was, but to no avail, and soon gave up. Just now, however, I came upon your site again (I’ve come across it before but forgot about it) and saw a submission from Las Cruces, New Mexico that was the same kind of beetle, that now I know is a Desert Spider Beetle. My beetle was in El Paso, Texas, about a 45 minute drive from Las Cruces. Well, just wanted to share my picture and say thanks for helping me ID this guy (it was killing me not to know!) and that your site is great! Keep up the good work!  🙂

Desert Spider Beetle
Desert Spider Beetle

Hi Jen,
Your Desert Spider Beetle is a Blister Beetle in the genus Cysteodemus.  We are not certain of the exact species, but we are very happy our site assisted you in the identification.

Letter 10 – Desert Spider Beetle


Mottled yellow beetle, 1″ long with rounded body about the size of a nickle.
Thu, Apr 23, 2009 at 11:01 AM
This bug was moving very quickly across our cement patio to our bermuda grass lawn about 8:30 am, April 23, 2009. It has a very round back and head. It is mottled black with yellow, head is solid yellow; underbelly is shiny black. It appeared to be climbing stalks of grass, possibly nibbling on the ends; it tumbled off the stalks often, moving on to other pieces of grass. It moved almost too quickly to get a clear photo.
Lake Havasu City, Arizona

Inflated Beetle
Inflated Beetle

Hi Julia,
This is a Desert Spider Beetle or Inflated Beetle, Cysteodemus armatus, one of the Blister Beetles.  According to BugGuide, it is found in Arizona, Nevada and California.  Spring is the time of year we get the most Blister Beetle reports, and a relative, the Master Blister Beetle, is our Bug of the Month.

Letter 11 – Desert Spider Beetle


Anza Borrego Spider??
March 31, 2010
We were at Anza Boreggo this past Saturday (03-27-10), Spring Season. We were walking up one of the canyons, rocks. And I went to an area where there were some flowering cactus, and other wild flowers. As I was approaching a flower, I noticed what originally looked like a beetle! UNTIL, it started to move and put its two front legs on a flower!!! Then it looked like a spider! What kind of spider is this? It camouflages as a piece of an orchid flower leaf as well! The body was huge and bulbous!
Anza Borrego

Desert Spider Beetle

Hi Crystal,
Your photo is lacking the kind of detail that would make our identification easier, but we believe this is a Desert Spider Beetle, Cysteodemus armatus, which may be viewed on BugGuide.

Hi Daniel!
Thank you very much for your quick and very accurate response!  It most definitely looks like a Desert Spider Beetle!!!  So I was right to think it was a beetle; I got a little freaked out the moment it looked like a spider.  Sorry I didn’t get closer to it, as I’m afraid of those things jumping at me!  It actually prevented me from going to the flowering cactus that I wanted to take a picture of! 🙂  But now I know exactly what it is!  What a specimen! 🙂

Letter 12 – Desert Spider Beetle


Bug seen in Anza-Borrego
April 4, 2010
Dear Bugman,
We saw this guy crawling across the sand in Anza-Borrego State Park on March 21, 2010. Any ideas?
Madena and Charlie
Anza-Borrego State Park, California

Desert Spider Beetle

Dear Madena and Charlie,
Just last week, we posted another photo of the Desert Spider Beetle or Inflated Beetle, Cysteodemus armatus, and that specimen was also from Anza-Borrego.  Your photo has much crisper detail than the photo we posted earlier.  You can read more about this fascinating beetle on BugGuide.

Letter 13 – Desert Spider Beetle


found a beautiful bug, but can’t find it anywhere.
April 11, 2010
My husband and I were out off roading in Southern New Mexico today and came across this little guy running across the road. The bright metallic blue/green caught our eyes… He was a fast little booger, and really didn’t want his picture taken. We think it’s a beetle of some kind, but not sure.
Southern New Mexico

Desert Spider Beetle

Read more

Do Spider Beetles Bite? Debunking Common Myths

Spider beetles are a type of beetle that may resemble spiders, owing to their superficial similarities in appearance. These beetles, found across the United States, are known to infest stored products and can be a common household nuisance, though not as well-known as other pests^[1^]. Although spider beetles resemble spiders and might give some people … Read more

Do Spider Beetles Have Wings? Unraveling the Mystery

Spider beetles are common pests found in stored products, but their physical appearance may cause confusion. These insects are two to five mm long, oval or cylindrical, long-legged, and brown in color with a superficial resemblance to spiders, hence their name source. While many insects have wings, spider beetles possess a unique structure. Their first … Read more

How to Get Rid of Spider Beetles: Quick and Easy Solutions

Spider beetles are a common pest that infest stored products in households. They are not as well known as other household pests, but their presence can cause damage to your belongings. These small, long-legged beetles are typically two to five mm long and brown in color with a superficial resemblance to spiders, giving them their … Read more