What Do Trapdoor Spiders Look Like? A Quick Guide to Identifying Them

Trapdoor spiders are fascinating creatures that can often be tricky to identify due to their well-camouflaged burrows. These spiders belong to the Ctenizidae family and can be found predominantly in the East and Southwest regions of the United States, with the Ummidia genus being the most diverse, consisting of approximately 50 species source.

If you’re looking to spot these elusive arachnids, it’s essential to be familiar with their appearance. Trapdoor spiders typically have a chunky, heavy build. Adult females, for instance, can reach up to 1.5 inches in length source. They sport eight legs, as with all spiders, and unique arrangements of their eyes could help differentiate them from other spider species. Keep in mind that these spiders may possess varying features and colors, depending on the specific genus and species of the trapdoor spider.

As you explore the world of trapdoor spiders, understanding their unique appearances will not only broaden your knowledge of arachnids but also allow you to appreciate these fascinating creatures for their remarkable adaptations and camouflage abilities. Remember to observe them from a safe distance and take care not to disturb their natural habitats.

Physical Features

Body Size and Color

Trapdoor spiders are usually medium to large-sized spiders. The males are generally smaller, while females tend to be larger. Their body color can range from dark brown to black, often providing camouflage within their natural habitat. For example, the brown trapdoor spider can easily blend in with the soil.

Abdomen and Thorax

Similar to other mygalomorph spiders, trapdoor spiders have a robust body structure. Their abdomen is rounded and often covered in fine hairs, while their thorax (the middle body part) is bulky, housing their legs, and contains powerful muscles.

8 Eyes and Fangs

These spiders are equipped with 8 small eyes, usually arranged in two rows. Their eyes help them perceive light, but their main sensory information comes from their fangs and pedipalps. Trapdoor spiders have large, downward-pointing fangs, which are used for capturing prey and injecting venom.

Leg Span and Pedipalps

Trapdoor spiders have impressive leg spans, which can reach several centimeters, depending on the species. Their legs are equipped with double spurs and a range of sensory hairs that help them navigate and sense their surroundings. Interestingly, the pedipalps (small, leg-like appendages) are shorter and sturdier, used for sensing and manipulating their environment, handling prey, and during mating.

Let’s compare some features of male and female trapdoor spiders:

Feature Male Female
Body size Smaller Larger
Leg span Slightly shorter Slightly longer
Reproductive role Fertilize eggs Lay and guard eggs

In summary, trapdoor spiders are well-equipped with a sturdy body, impressive legs, powerful fangs, and a keen sense of their surroundings. Remember that these spiders vary in size and color, and their physical features are optimized for their environment, hunting, and reproducing.

Habitat and Distribution

Burrow and Silk Webs

Trapdoor spiders are known for their unique living arrangements. They create silk-lined burrows in the ground, which serve as their homes and hunting grounds. The entrance of their burrows is often concealed by a hinged trapdoor made of silk, soil, and plant material. These doors are well camouflaged, allowing the spider to remain hidden from predators and prey. They typically dwell in areas with ample leaf litter, providing them with cover and resources for constructing their burrows.

Examples of burrow characteristics:

  • Silk-lined tunnels
  • Trapdoors made of a mix of silk, soil, and plant material
  • Hidden in leaf litter or garden debris

Geographical Locations

Trapdoor spiders have a widespread distribution across various continents:

  • North America: They are commonly found in the eastern and southwestern United States, extending as far north as Colorado1.
  • South America: They also inhabit parts of South America, although their presence is less common compared to North America.
  • Africa: Several species of trapdoor spiders can be found throughout Africa, demonstrating their adaptability to various ecosystems.
  • Japan: Some trapdoor spider species have been documented in Japan.

Their habitat preferences include gardens and ground-dwelling environments, making them frequent inhabitants of leaf litter and soil-covered areas.

In summary, trapdoor spiders are widely distributed across the globe, thriving in ground-dwelling habitats where they construct silk-lined burrows with hidden trapdoors. Their tendency to live in leaf litter and garden debris makes them somewhat elusive creatures that play an essential role in their ecosystems.

Feeding and Hunting Strategies

Prey and Predators

Trapdoor spiders are skilled predators that primarily feed on insects and other small arthropods, such as beetles, cockroaches, crickets, flies, and centipedes. These spiders rely on their hunting abilities to catch prey, rather than spinning webs.

When it comes to predators, trapdoor spiders can fall prey to larger spiders, birds, and small mammals. Using their remarkable camouflage skills and underground burrows is crucial in avoiding these threats.

Camouflage and Mating

Trapdoor spiders are well-adapted for a life of stealth and secrecy, sporting a natural camouflage that helps them blend into their environment. They make their homes in silk-lined burrows, typically hidden under rocks or vegetation, and use a trapdoor-like lid made of soil, leaves, and silk to remain concealed from both prey and predators.

In terms of mating, trapdoor spiders use a range of signals to communicate. Female trapdoor spiders release pheromones to attract males, who then approach and cautiously court the females. Mating usually occurs within the safety of the female’s burrow.

A comparison table of trapdoor spiders’ feeding and hunting strategies:

Aspect Trapdoor Spiders
Prey Beetles, cockroaches, crickets, flies, centipedes
Predators Larger spiders, birds, small mammals
Camouflage Burrows, vegetation, trapdoor-like lids, natural colors
Mating Pheromones, cautious courtship, mating occurs in burrows

Remember, trapdoor spiders are fascinating creatures with unique hunting and mating strategies. By understanding their behaviors and adaptions, you can appreciate their significance in the intricate ecosystems they inhabit.

Species Identification

Family and Genera

Trapdoor spiders are fascinating arachnids belonging to the Mygalomorphae infraorder. These spiders have different families, with the most prominent one being the Ctenizidae family. However, you will also find other families, such as:

  • Idiopidae
  • Actinopodidae
  • Cyrtaucheniidae
  • Halonoproctidae
  • Migidae

Each family consists of various genera, such as the genus Cyclocosmia in the Ctenizidae family.

Common Trapdoor Species

There are several common species of trapdoor spiders that you might come across. Some examples include:

  • Sigillate Trapdoor Spider: These spiders have a unique, shiny pattern on their abdomen, helping identify them easily.
  • Brown Trapdoor: Known for their brown color, these spiders are usually found in Australia and southern Asia.
  • Funnel-web Spider: These spiders create web-funnel structures for trapping prey and can be found mostly in Australia.
  • Cork-lid Trapdoor Spider: Part of the genus Cyclocosmia, these spiders have a distinctive flat, circular abdomen with a unique pattern that resembles a cork lid.

Here is a comparison table of some features of these trapdoor species:

Species Features
Sigillate Trapdoor Shiny pattern on abdomen, large fangs
Brown Trapdoor Brown color, common in Australia and southern Asia
Funnel-web Spider Web-funnel structures, venomous, mainly in Australia
Cork-lid Trapdoor Flat, circular abdomen with cork-like pattern, genus Cyclocosmia

When trying to identify trapdoor spiders, pay attention to their physical appearance, habitats, and web structures. This will help you differentiate between various species and learn more about these fascinating creatures.

Behavior and Reproduction

Mating Cycle

Trapdoor spiders are known for their unique mating behaviors. The male trapdoor spiders seek out females during their nocturnal wanderings. When a male finds a female’s silk-lined burrow, he taps on the web to signal his presence. If the female is receptive, she will emerge and allow the male to mate with her.

Trapdoor spiders face various threats during their mating cycle. For example, bandicoots may prey on them. Consequently, these spiders must be cautious and alert while seeking a mate.

Offspring

After a successful mating, female trapdoor spiders lay their eggs in the safety of their underground burrows. They keep the eggs in a silk cocoon and provide protection until the spiderlings hatch. Upon reaching maturity, the young spiders leave their mother’s burrow to build their own silk-lined burrows and start the cycle again.

Some key features of trapdoor spider reproduction include:

  • Females lay eggs in a silk cocoon within their burrows.
  • Offspring are provided protected until they reach maturity.
  • Once mature, spiderlings disperse to build their own burrows.

In summary, trapdoor spider behavior and reproduction involve a unique nocturnal mating cycle and protective care of their offspring in silk-lined burrows. By understanding these spiders’ fascinating behaviors, you can better appreciate their role in the ecosystem and their remarkable survival strategies.

Threats to Humans

Aggression and Bites

Trapdoor spiders are not generally known to be aggressive towards humans. However, they might bite if they feel threatened or provoked. A trapdoor spider’s bite can be quite painful due to its large fangs, which can cause a stabbing sensation and result in local pain and swelling1.

It is important to remember that these spiders are more focused on finding insects to prey on rather than attacking humans. Just like most spiders, they prefer to avoid contact with humans if possible.

Venom and Medical Attention

While trapdoor spiders are venomous, their venom is not considered to be highly toxic to humans1. It means that, typically, you would not need to seek medical attention if bitten by one1.

However, it is always a good practice to monitor the bitten area for any signs of infection or adverse reactions. If you experience severe pain, difficulty breathing, or any other concerning symptoms, please consult a healthcare professional.

References

Trapdoor spiders belong to the order Araneae, and their most speciose genus is Ummidia, which consists of about 50 species1. These spiders are known for living in silk-lined, underground burrows and are widespread in the East and Southwest United States, extending up to Colorado1.

These spiders can be quite large, with some females reaching up to 1.5 inches in length2. Their physical appearance includes a chunky, robust body, making them potentially our heaviest spiders2.

In terms of their behavior and lifestyle, trapdoor spiders are ground-dwelling creatures that exhibit poor dispersal3. However, some species of the Ummidia genus have been known to disperse by ballooning3.

To better understand the features that define trapdoor spiders, here are some key characteristics:

  • Silk-lined, underground burrows1
  • Chunky, robust body2
  • Ground-dwelling creatures3
  • Poor dispersal, some species use ballooning3

Footnotes

  1. University of Arkansas – Trapdoor Spider 2 3 4 5 6 7

  2. Mississippi State University Extension 2 3

  3. PubMed Central 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 – Trapdoor Spider

 

Subject: Spider or Beetle??
Location: Raleigh, NC
July 8, 2017 9:55 pm
Seen in a backyard in Raleigh, NC. on July 8th, 2017. Is it a spider or beetle?
Signature: Doesn’t matter

Trapdoor Spider

This is a harmless, male Trapdoor Spider in the genus Ummidia, which you can verify by comparing your image to this BugGuide image.

Letter 2 – Trapdoor Spider

 

Subject: Possible trapdoor spider?
Location: Eastern Kentucky
April 11, 2017 2:29 pm
I was pulling up clumps of ornamental grass from a raised bed and noticed a white “sack” that came up on the roots of one clump. There was a tear on one side of the sack and I could see a large, dark, shiny spider inside. While I was trying to figure out what to do about it, I noticed tiny spiders crawling out of the sack. (The second image shows them.) I’m assuming they were her babies. I left her there with the youngsters while I finished cleaning the raised bed. When I came back, she had crawled out of the nest and was walking across the deck. I encouraged her to move where she wouldn’t be stepped on and put the clump of grass and nest beside her. I went back later, but she was nowhere to be seen. I’ve checked the images here on whatsthatbug and I think she’s a trapdoor spider.
Signature: Kentucky Gin

Cork-Lid Trapdoor Spider

Dear Kentucky Gin,
We agree that this is a Trapdoor Spider, probably a female Cork-Lid Trapdoor Spider in the genus
Ummidia based on this BugGuide image.  According to BugGuide:  “Dig tunnel in ground and seal with a silk-hinged lid. They hide under this lid and make forays out when prey is sensed, presumably by vibration. Males are often found wandering in late spring, presumably looking for mates.”  Because of your gentle kindness in relocating this little lady, we are tagging this posting with the Bug Humanitarian Award.

Cork-Lid Trapdoor Spider with Spiderlings
Cork-Lid Trapdoor Spider

Letter 3 – Trapdoor Spider

 

Large Spider Identity
Hi. Although your site is very extensive, I have not been able to determine what type of spider this is. We live outside of Austin, TX and we found this guy in our garage. He could have been forced into the neighborhood by nearby construction. He has fangs and very distinctive/unusual markings on his bottom side. Thank you so much for any information you can give me.
Angel G

Hi Angel,
This is a male Trapdoor Spider. The female rarely leaves her burrow and has shorter legs. The males, which are shorter lived, leave their burrows to search for mates and often meet untimely ends. They are not dangerous.
.

Letter 4 – Trapdoor Spider

 

Large spider in Austin
I found this guy climbing up my house on a cool rainy night in Austin. Body about 1 1/2" in length. Maybe a male trapdoor spider?
Jason.

Hi Jason,
We agree with your identification. Either the rains flood the burrows causing the spiders to travel, or more likely, the rains trigger mating behavior, causing the males to travel in search of mates.

Letter 5 – Trapdoor Spider

 

Trapdoor spider
Hi,
I have occasionally come to lurk around your site. Beautiful and informative! Thank you for all your hard work! I LOVE bugs. I always have. I understand that you are very busy but thanks for giving this a read anyway.
Last spring while helping at the local co-op organic farm I discovered a large, tubular tunnel in the dirt (we were preparing the garden bed for planting). Upon further investigation, I found a large spider hiding out in there. A friend took a nice picture of it before I let it go out of harm’s way. I did a little research online and have figured that this is a trapdoor spider. Unfortunately, I can’t seem to find any info on them living in this area. I live in Southeastern Long Island (New York). Any thoughts? (maybe global warming???)
Thanks!
Tamar

Hi Tamar,
We occasionally jokingly use global warming as an excuse for range expansion, but the truth of the matter is that in many places there are not complete studies of flora and fauna. BugGuide does not show New York as a place where Trapdoor Spider images have originated, but that isn’t conclusive. At any rate, we agree that this is a Trapdoor Spider.

Letter 6 – Trapdoor Spider

 

Spider
January 1, 2010
Trying to figure out what kind of spider this is
Chris
St Croix, USVI

Trapdoor Spider
Trapdoor Spider

Happy New Year Chris,
We believe this is a male Trapdoor Spider in the genus Ummidia which is found in the Southern U.S. and the neotropics according to BugGuide.

Letter 7 – Trapdoor Spider

 

Trapdoor Spider – CA
Location: Berkeley, CA
November 17, 2010 3:20 am
I saw this spider outside of a well maintained building near a nature reserve in Berkeley, CA. I took the photos 3 nights ago, in mid November; weather has been warm, barely any rain, and with some humidity. It looks to me like a trapdoor spider, but it doesn’t look like ”the” California Trapdoor spider. You’ve gotta tell me, what’s this bug?
Signature: Jim

Trapdoor Spider

Hi Jim,
You are correct that this is a Trapdoor Spider and you are also correct that it is not the California Trapdoor Spider,
Bothriocyrtum californicum.  We believe it is probably a Tube Trapdoor Spider in the genus Calisoga based on this image posted to BugGuide.

Trapdoor Spider

Letter 8 – Trapdoor Spider

 

Subject: Trap Door Spider
Location: Central NC
May 29, 2017 4:47 pm
Photo to go with my comment on
2004/07/03/trapdoor-spider-in-north-carolina/
Signature: Laura Wolf

Trapdoor Spider

Dear Laura,
Thanks for sending in your image of a male Trapdoor Spider in the genus
Ummidia.

Letter 9 – Trapdoor Spider

 

Subject:  East Texas Arachnid
Geographic location of the bug:  East Texas
Date: 10/10/2017
Time: 11:29 AM EDT
Greetings! Long-time reader and fellow entomomaniac here. I have a friend who found this fellow around her home in East Texas in September. I’ll admit that my arachnid knowledge is lacking; my best guess was that it was a juvenile tarantula that had recently molted, but that’s as far as I’ve gotten. Any assistance would be greatly appreciated!
How you want your letter signed:  Dani Gardner

Trapdoor Spider

Dear Dani,
This is not a Tarantula, but it is a Trapdoor Spider that is classified along with Tarantulas as a primitive spider in the infraorder Mygalomorphae. We will attempt to provide you with a species identification.

Daniel,
Sounds good! Thank you very much for your help!
Dani

Letter 10 – Trapdoor Spider

 

Subject:  Large Hairy Spider (But Not a Wolf!)
Geographic location of the bug:  Southern Fauquier County, VA
Date: 01/06/2018
Time: 09:59 AM EDT
We found this on June 25th, 2017, scuttling across my brother’s foot in my mother’s backyard. Fortunately he is a pretty laid-back guy, so no squealing or panic ensued, but we knew something was going on when mid-sentence he stopped talking and his eyes got as big as dinner plates.
My mother has have lived here for over 50 years (grew up right down the street) and when both she, myself and my brother were kids we practically lived outdoors and have never seen these. After this first sighting, my mother saw 3 or 4 more in pretty quick succession, so I would assume there is a breeding population if they’ve just moved to the area.
I didn’t take a measurement, but judging from the container from fang to rear the spider was about 3/4.” So not quite as long as the wolf spiders we have here, but this one was “fatter” and bulkier than the wolf. It was also very aggressive, lunging at the “poking stick” we employed and baring his very impressive fangs rather than run away or just stand it’s ground. Unfortunately you may only see the chelicera in the photo, not sure if the part you can see curling under is more of the chelicera or the fang, but the fangs were massive and very prominent and distinct from the chelicera. All in all, this spider generally looked like a tarantula without the hairy body.
I appreciate any help you can provide. We have searched several resources and have been unable to find this spider, either amongst indigenous or foreign species.
How you want your letter signed:  April

Trapdoor Spider

Dear April,
This is a Trapdoor Spider in the genus
Ummidia.  According to BugGuide:  “Virginia south to Florida, west to Arizona, also neotropics” though BugGuide data does include sightings from Ohio and Maryland as well.  According to BugGuide, these Trapdoor Spiders “Dig tunnel in ground and seal with a silk-hinged lid. They hide under this lid and make forays out when prey is sensed, presumably by vibration. Males are often found wandering in late spring, presumably looking for mates.”  Trapdoor Spiders and Tarantulas are classified together with other primitive Spiders in the infraorder Mygalomorphae.  Trapdoor Spiders are not considered dangerous to humans.

Letter 11 – Trapdoor Spider

 

Subject:  Spider ID
Geographic location of the bug:  Claremore OK
Date: 07/05/2018
Time: 01:33 PM EDT
Your letter to the bugman:  Please ID this spider.
How you want your letter signed:  Darlene Armstrong

Male Trapdoor Spider

Dear Darlene,
This is a male Trapdoor Spider in the genus
Ummidia, and here is a BugGuide image for comparison.  Male Trapdoor Spiders are generally sighted more often than females because females are more sedentary while males wander in search of a mate.

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.

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