Cork Lid Trapdoor Spider: Quick Guide to These Unique Creatures

The Cork Lid Trapdoor Spider is a fascinating creature that belongs to the group known as “cork-lid trapdoor spiders.” These amazing arachnids have a unique way of catching their prey, leaving many people intrigued by their stealth and cunning.

These spiders are known not only for their impressive leg span but also for their hefty body size. For instance, the females can grow up to 1.5 inches long. They build silk-lined burrows for their homes, which makes it an interesting aspect of their biology. Found in various regions across the United States, the Ummidia genus is the most diverse, featuring around 50 species.

In the world of spiders, the Cork Lid Trapdoor Spider has its own unique appearance and traits that set it apart from others. In this article, we’ll explore its habitat, behavior, and other interesting facts, giving you an all-encompassing understanding of this fascinating spider.

Cork Lid Trapdoor Spider Overview

Species and Genera

Cork-lid trapdoor spiders belong to the family Ctenizidae, and the most commonly known genus is Ummidia. There are about 50 species under this genus, and some are yet to be described. These spiders live in silk-lined, underground burrows, and can mostly be found across the Eastern United States and the Southwest region up to Colorado.

Classification and Taxonomy

The cork-lid trapdoor spiders are part of the infraorder Mygalomorphae, which includes other mygalomorph spiders like tarantulas and funnel-web spiders. The family Ctenizidae once included other genera like Cyclocosmia, but they are now classified under the separate family Halonoproctidae. Here’s a comparison table:

Features Ctenizidae (Cork-Lid Trapdoor Spiders) Halonoproctidae
Taxonomy Infraorder Mygalomorphae, Family Ctenizidae Infraorder Mygalomorphae, Family Halonoproctidae
Genera example Ummidia Cyclocosmia
Habitat Eastern United States, Southwest region Varies depending on species

Distinctive characteristics of cork-lid trapdoor spiders:

  • Underground burrows with silk lining
  • Cork-like lid to seal their burrows
  • Robust body size (e.g., 1.5 inches long for females)

Some advantages and disadvantages of cork-lid trapdoor spiders’ lifestyle include:


  • Well-protected from predators in their burrows
  • Efficient at capturing prey due to their trapdoor ambush method


  • Limited mobility since they primarily stay in their burrows
  • May be vulnerable to habitat destruction or disturbances

Physical Characteristics and Behavior

Anatomy and Venom

The cork lid trapdoor spider is a fascinating arthropod known for its unique anatomy and behavior. Some key features of its anatomy include:

  • A highly sclerotised, or hardened, exoskeleton
  • Specialized silk-producing glands
  • Poisonous venom, used for subduing prey

These spiders are capable of delivering painful bites to humans, but they are not considered highly venomous or life-threatening. In comparison to other arthropods, trapdoor spiders have specific traits that distinguish them from other spider species.

Spider Type Silk Production Poisonous Bite Highly Sclerotised Exoskeleton
Cork Lid Trapdoor Yes Mildly Yes
Common House Spider Yes No No

Burrow Construction and Habitat

Cork lid trapdoor spiders showcase their skills in burrow construction, creating elaborate underground homes lined with silk. These burrows feature a well-camouflaged, hinged door, or “lid,” that the spider uses to conceal itself from predators. The lid is composed of silk, soil, and debris.

The habitat of these spiders varies, but they often prefer environments such as:

  • Forest floors
  • Grassy fields
  • Gardens with plenty of plant cover

The burrows and habitat of cork lid trapdoor spiders provide protection from predators, while also allowing them easy access to insects and other prey. The well-adapted, physical characteristics and behavior of these spiders make them successful arthropod predators in their natural environments.

Feeding and Prey

Cork lid trapdoor spiders are ambush predators. They patiently wait for their prey in their burrows.

Their diet consists mainly of insects and other arthropods. Occasionally, they may also consume small vertebrates.

Here are the main features of their feeding strategy:

  • Burrows: Lined with silk, providing a secure hiding spot and ambush location.
  • Trapdoor: Operated with silk threads, camouflaged with debris to blend into surroundings.
  • Sensing prey: Detect vibrations through the ground, using sensitive legs and body hairs.
  • Ambush: Quickly open trapdoor and catch unsuspecting prey with their strong, venomous fangs.

Fun fact: Their strong jaws and venom enable them to subdue larger or tougher prey.

Cork lid trapdoor spider’s feeding behavior is comparable to other trapdoor spiders. Here is a comparison table:

Feature Cork Lid Trapdoor Spider Other Trapdoor Spiders
Burrow Silk-lined Silk-lined
Trapdoor Camouflaged with debris Slightly camouflaged
Prey Detection Vibrations through ground Vibrations through ground
Ambush Speed Quick Quick

In summary, cork lid trapdoor spiders are efficient ambush predators. Their feeding strategy relies on well-built, camouflaged burrows and quick, venomous attacks.

Reproduction and Lifecycle

The cork lid trapdoor spider has a fascinating reproduction and lifecycle. While researching specifics on this spider’s lifecycle is limited, we can look at general aspects of trapdoor spiders, which belong to the family Ctenizidae.

Males and females have different lifespans. Males, typically shorter-lived, die soon after reaching maturity. In some extreme cases, males may even die within 5 minutes of completing their final molt. On the other hand, females live longer, more sedentary lives, staying inside their burrows.

Mating usually occurs when males venture out to find receptive females. There might be fierce competition, with males fighting each other for the chance to mate. After mating, females lay their eggs within the safety of their burrows.

  • Males: Shorter lifespan, die after reaching maturity, roam to find a mate.
  • Females: Longer lifespan, stay in burrows, lay eggs inside burrow.

It is worth noting that the cork lid trapdoor spider, like other trapdoor spiders, has a unique adaptation in the form of trapdoor burrows. These silk-lined burrows not only provide a safe place for the spider to molt, mate, and lay eggs but also help the spider catch its prey effectively. The burrow’s “cork lid” allows the spider to remain hidden until it detects vibrations from nearby prey and ambushes it.

Keeping the information short and concise, the following table compares males and females in terms of their lifecycles:

Aspect Males Females
Lifespan Shorter, die after reaching maturity Longer, provide maternal care
Behavior Venture out to find mates Sedentary, stay in burrows
Reproduction Fight for mating opportunities Lay eggs and care for them in burrows

In summary, the cork lid trapdoor spider’s reproduction and lifecycle involve unique adaptations and distinct differences between males and females. These spiders continue to intrigue researchers and enthusiasts alike.

Geographical Distribution and Habitat

Cork-lid trapdoor spiders are primarily found in the United States, with a wide distribution in the East and Southwest, stretching up to Colorado. Their presence is particularly notable within the Ummidia genus, which comprises around 50 species.

These spiders favor underground burrows as their habitat. They meticulously create silk-lined burrows to reside in, which allows them to stay hidden and ambush their prey with ease.

Cork-lid trapdoor spiders have not been documented in Europe or Central Asia. While Greece and Turkey have a diverse spider population, these trapdoor spiders are absent from those regions.

Region Presence of Cork-lid Trapdoor Spiders
United States Yes
Europe No
Central Asia No
Greece No
Turkey No

To summarize, cork-lid trapdoor spiders can be encountered throughout certain parts of the United States, preferring underground burrows as their habitat. They are virtually absent in Europe, Central Asia, Greece, and Turkey.

Human Interaction

The Cork Lid Trapdoor Spider (genus Ummidia) is a spider that has caught the interest of many people in the online world, especially among arachnid enthusiasts. For instance, you may stumble upon images and discussions about these spiders on Facebook or Reddit, where communities like r/oddlyterrifying can be found. The unique burrow-building characteristics, as well as their occasional encounters with humans, spark curiosity.

Some people might have concerns regarding the venomous nature of the spider. Trapdoor spiders are indeed venomous; however, their toxic impact on humans is low. While their bites can cause a reaction (such as localized pain, redness, and itching), they are generally not considered dangerous or life-threatening to humans.

  • Encounters can happen when humans disturb their habitats or when trapdoor spiders wander away from their burrows.
  • Their bites seldom occur and are mostly defensive.

Comparing the potential danger posed by cork lid trapdoor spiders to other more dangerous spiders:

Spider Venomous Bite Effects on Humans Level of Danger to Humans
Cork Lid Trapdoor Spider Yes Pain, redness, and itching Low
Brown Recluse Spider Yes Skin necrosis, systemic symptoms High
Black Widow Spider Yes Intense pain, muscle cramps, abdominal pain High

In conclusion, cork lid trapdoor spiders generate interest on social media platforms due to their unique behaviors and appearance. They are venomous, but their bites are typically not dangerous to humans, making them a fascinating subject rather than a cause for concern.

Research and Studies

Cork-lid trapdoor spiders are an interesting group that have been studied using molecular phylogenetics, focusing on phylogeny and taxonomy. One such study by Phylogeny and Classification of the Trapdoor Spider Genus examined the relationships among the morphologically conserved trapdoor spiders.

Key features of trapdoor spiders include:

  • Silk-lined burrows with trapdoor lids
  • Predatory nature
  • Unique morphology

Several spider families have been researched, such as:

  • Liphistiidae
  • Barychelidae
  • Cyrtaucheniidae
  • Idiopidae
  • Nemesiidae

Some well-known genera are:

  • Stasimopus (Stasimopidae)
  • Cteniza
  • Cyrtocarenum
  • Baltocteniza
  • Electrocteniza

The term ‘ctenizid’ comes from the Greek word κτενὶζειν (ktenizein), which implies combing or carding. The World Spider Catalog, created by Thorell, has documented the various genera and their characteristics.

Notable researchers, such as Jason Bond, a professor in the field, have contributed significantly to the understanding of trapdoor spiders. Bond and his team have used anchored hybrids and molecular phylogenetics and evolution techniques in their research.

Here is a comparison of some spider families:

Family Features
Liphistiidae Primitive, segmented plates on abdomen, Asia-based distribution
Barychelidae Stout build, strong legs, tropical and subtropical distribution
Cyrtaucheniidae Lack urticating hairs, diverse burrow types, global distribution
Idiopidae Australasian distribution, diverse morphology, heavy-bodied
Nemesiidae Primarily New World distribution, size variation, diverse habitat

In summary, trapdoor spider research has delved into molecular phylogenetics, taxonomy, and morphology, with notable researchers like Jason Bond contributing to our understanding of this fascinating group of spiders.

Fun Facts and Trivia

Cork-Lid Trapdoor Spiders:

  • These spiders are known for their unique burrow entrances. They create silk-lined, underground burrows with a door made of soil and silk.
  • The trapdoor is almost perfectly camouflaged, making it difficult to spot. This allows the spider to ambush its prey effectively.

Ancient Coin Connection:

  • Interestingly, the design of the spider’s burrow resembles the shape of an ancient coin with its circular structure and raised edges.
  • This serves as a fascinating comparison, highlighting the spider’s intriguing burrow design.

Sand and Cork-Lid Trapdoor Spiders:

  • These spiders prefer loose, sandy soil for their burrows. This helps them easily create their trapdoors.
  • Sand also allows the doors to blend seamlessly into the environment, providing excellent camouflage.

Comparison Table:

Feature Cork-lid Trapdoor Spider Common House Spider
Burrow type Silk-lined, with trapdoor None
Habitat Loose, sandy soil Inside homes/structures
Camouflage Trapdoor blends with soil Color blends with surroundings

Pros and Cons of Cork-lid Trapdoor Spiders:


  • Excellent camouflage
  • Unique trapdoor design
  • Efficient ambush predators


  • Limited to environments with appropriate soil
  • Less effective in areas with predators that can locate and dig up their burrows

In summary, cork-lid trapdoor spiders have fascinating features, from their unique burrows to their efficient hunting style. By understanding more about these spiders and their connection to ancient coins and sandy habitats, we can appreciate the diverse web of nature.

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 – Cork Lid Trapdoor Spider


thick black spider
April 24, 2010
very slow moving, thick spider with shiny legs but flat black abdomen. joints in legs were white-ish.
henry county, georgia

Cork Lid Trapdoor Spider

Hi Travis,
This awesome spider is a Cork Lid Trapdoor Spider in the genus Ummidia, and there is information available on BugGuide where most of the submissions hail from Georgia.  We believe your specimen is a female because of her more compact legs.  The longer legged males travel in search of females, but females rarely leave their burrows, which makes your sighting a bit unusual.

Letter 2 – Cork Lid Trapdoor Spider drowned in swimming pool


Subject: Trapdoor spider?
Location: Northeast Louisiana
June 6, 2013 6:15 pm
When I went out to check my swimming pool skimmer, as I do every morning, I found a large black spider which appeared to be dead in the bottom of the trap. I pulled the trap out and collected the spider in a jar, startled by the size of it. At first I thought it was a small tarantula, but it didn’t have hair on it and I new that is characteristic of them. I took it to work with me to see if anyone new what it was. No one there new what it was, so after doing some research I found the funnel web spider in Australia (yikes), which looks almost identical to it, but I was confident I didn’t have one of those. Finally I found an image of the trapdoor spider that was very close to my spider. I hope you can tell me for sure what I have, and the sex of the spider. For a note of geography, I live in northeast Louisiana and found the spider on June 5, 2013.
Signature: Bugbunny

Cork Lid Trapdoor Spider
Cork Lid Trapdoor Spider

Dear Bugbunny,
We agree that this is a Trapdoor Spider, most likely a Cork Lid Trapdoor Spider in the genus
Ummidia.  See BugGuide for some matching photos. 

Cork Lid Trapdoor Spider
Cork Lid Trapdoor Spider

The short legs indicate that this is most likely a female spider and female Trapdoor Spiders do not generally wander far from their holes.  Male Trapdoor Spiders, on the other hand, often wander in search of a mate and we frequently get reports of male Trapdoor Spiders drowning in pools

Cork Lid Trapdoor Spider
Cork Lid Trapdoor Spider

Letter 3 – Cork Lid Trapdoor Spider


Spider ID unknown
Hey there bugman! Big fan of the website, keep up the good work. Anyway, I found this beauty on thanksgiving, and have no idea what it is exactly. I live in Maryland. Spider is about 2 inches from front to back(including legs), in this photo. Spider was very calm. I just cant seem to find anything that looks like it on the internet. At first I thought wolf but after looking at many different kind, I am not so sure any more.

This positively gorgeous spider is a Cork Lid Trapdoor Spider in the genus UMmidia. There are numerous images on Bugguide which has this to say: “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.” Perhaps global warming has upset this guy’s timing.

Letter 4 – Cork-Lid Trapdoor Spider


Subject: Large black spider with a large single white spot
Location: Oak Island, NC
September 8, 2013 11:29 am
Found this near our water spigot in Oak Island, NC. Just curious what it is. It moves fairly quick and has a size of a walnut.
Signature: Amanda

Trapdoor Spider genus Ummidia
Cork-Lid Trapdoor Spider genus Ummidia

Dear Amanda,
We recognized your spider as a Trapdoor Spider, but we cannot recall seeing an individual with the white markings.  We searched the BugGuide archives of the genus
Ummidia and found this matching photo.  There is a comment on that posting that indicates it is not a dangerous spider, but it might bite if carelessly handled.  According to BugGuide, they:  “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.”

Letter 5 – Cork-Lid Trapdoor Spider


Subject: Funnel Web or Trap Door Spider in Oklahoma
Location: Southeastern Oklahoma
September 15, 2013 8:44 am
I found this lady outside of our warehouse here in Southeast Oklahoma. Shiny black thorax and legs, brown abdomen with very short hairs. She was very aggressive. Any ideas one what it is? She looks like a funnel web spider or trap door spider but I have never seen one around here and I am interested to know the species. My coworkers were terrified as they are convinced it is a Sydney Funnel Web Spider, but that is a long way from home. Hope you have a better clue than I do! Second pic is the Australian big sister we fear.
Signature: Matt

Cork-Lid Trapdoor Spider
Cork-Lid Trapdoor Spider

Hi Matt,
This looks like a Cork-Lid Trapdoor Spider in the genus
Ummidia to us.  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.”  We believe your individual is a male.

Letter 6 – Cork-Lid Trapdoor Spider from Canada


Subject: Spider Found In Nelson, BC, Canada . Never Seen It Before
Location: Nelson, BC, Canada
April 11, 2014 4:57 pm
today during a walk i stumbled apon a spider that made my skin crawl just looking at it!! i have lived in Canada my whole life and have never seen one like this. unfortunatly some of these pictures were taken as it posed “belly up” but its legs are tucked and short and has some yellow marking on the lower underside.. im very curious into discovering what type of spider it is! please help
Signature: Regan

Cork-Lid Trapdoor Spider
Cork-Lid Trapdoor Spider

Dear Regan,
This is a Cork-Lid Trapdoor Spider in the genus Ummidia, and despite it making your skin crawl, it is a harmless species.  The spots on the underside of the abdomen are quite distinctive.  You can see a matching image on BugGuide.
  Spring rains may have flushed it from its burrow.

Cork-Lid Trapdoor Spider
Cork-Lid Trapdoor Spider

Letter 7 – Corklid Trapdoor Spider


Trap Door Spider
Location:  James Island, SC
October 6, 2010 6:08 am
Hi Bugman,
We love WTB. My wife swept up this spider whilst doing her daily chore. I think its a trap door spider. I flipped it over for a better look.
Signature:  Simply Bananas

Corklid Trapdoor Spider

Dear Simply Bananas,
We wanted to hurry to get one more post up before rushing to work since we had a connectivity issue today.  We agree that this is a Trapdoor Spider, probably in the genus
Ummidia which is well represented by specimens from the South in our archives and on Bugguide.  The view of the underside is quite nice, and it matches this image on BugGuide.

Corklid Trapdoor Spider


  • 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.

6 thoughts on “Cork Lid Trapdoor Spider: Quick Guide to These Unique Creatures”

    • We have other examples in our archives Cesar, but again, it is generally the males of the Trapdoor Spiders that wander in search of a mate and fall into pools.


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