Hourglass Trapdoor Spider: Quick Facts & Essential Info

The Hourglass Trapdoor Spider is a fascinating creature, known for its intriguing behavior and unique appearance. This arachnid belongs to the family Ctenizidae and predominantly lives in silk-lined, underground burrows across the United States. One of the most striking features of this spider is its ability to construct well-camouflaged trapdoors that blend seamlessly with the surrounding environment.

Unlike other spiders, Hourglass Trapdoor Spiders spend most of their lives in these burrows, waiting patiently for prey to pass by. Their diet mainly consists of insects and small arthropods, and they use their powerful jaws to capture and crush their prey. With around 50 species in the Ummidia genus, these spiders exhibit a remarkable level of diversity in size, color, and behavior.

Their fascinating lifestyle and captivating appearance make the Hourglass Trapdoor Spider a truly intriguing subject. As you learn more about these unique creatures, you’ll discover their incredible adaptations and the role they play in the ecosystem. Stay tuned for all you need to know about the Hourglass Trapdoor Spider.

Understanding the Hourglass Trapdoor Spider

Scientific Classification

The Hourglass Trapdoor Spider belongs to the family Cyclocosmiinae, specifically the genus Cyclocosmia¹. These spiders are related to other trapdoor spiders and are sometimes called Chinese Hourglass Spiders because they are native to China.

Physical Characteristics

Hourglass Trapdoor Spiders are known for their unique appearance. They have flat, round abdomens, often with an hourglass-shaped pattern.

• Size: These spiders range between 0.5 to 1.5 inches in length².
• Colors: They display darker brown shades on their abdomen and lighter colors on their legs¹.

Their physical adaptations help them survive, some of these include:

• Trapdoor construction: Similar to other trapdoor spiders, they create silk-lined burrows with a trapdoor made of soil and silk for hunting and protection³.
• Flat abdomens: Their abdomens have a hardened exoskeleton, which helps them quickly seal themselves in their burrows when threatened⁴.

While Hourglass Trapdoor Spiders share characteristics with other trapdoor spiders, their unique flat and round abdomens set them apart.

Life Cycle & Reproduction

Males vs. Females

Hourglass trapdoor spiders exhibit some differences between males and females. Males tend to be smaller and more slender. Females are larger and more robust.

Comparison Table:

Eggs & Spiderlings

• Females lay eggs in silk-lined burrows
• Spiderlings hatch from eggs after a specific incubation period

Females produce egg sacs that are off-white in color. The sacs are typically hidden in dark, sheltered areas. Spiderlings emerge from the egg sacs after a certain period (for example, 24 to 36 days in some spider species).

Habitat & Distribution

Global Presence

The habitat of the hourglass trapdoor spider primarily spans across the southeastern United States. This spider genus is yet to be discovered in other regions such as China, Africa, Canada, or Southeast Asia.

Environmental Factors

Hourglass trapdoor spiders thrive in environments with ample vegetation. They reside in:

• Silk-lined, underground burrows
• Gardens and areas with dense plant cover

These spiders have a preference for:

• Warm, humid conditions
• Soil that’s easy to dig and maintain burrows in

Burrow & Trapdoor Construction

Burrow Structure

Hourglass trapdoor spiders are known for their unique burrows, which they construct in the soil. Some key features of their burrows include:

• Lined with silk threads
• Underground tunnels
• Customized for each spider

The spiders use their silk in combination with soil to create a stable and comfortable living environment. The burrow structure typically consists of a single entrance, with the tunnel leading down to a small chamber where the spider resides.

Trapdoor Mechanism

Trapdoor spiders build a hidden door to conceal the entrance to their burrow. This door is cleverly constructed using:

• Layers of silk
• Soil and debris
• Camouflage patterns

The trapdoor is attached to the burrow by silk threads, which also help the spider sense potential prey, as they vibrate when disturbed. Here is a comparison between hourglass trapdoor spiders and other trapdoor spiders:

Overall, the unique burrow and trapdoor construction of hourglass trapdoor spiders reflects their adaptation to their environment, allowing them to remain hidden while waiting for their prey.

Behavior & Diet

Prey and Hunting Techniques

The Hourglass Trapdoor Spider primarily preys on insects like grasshoppers, crickets, and flies. They have a unique hunting technique:

• They live in silk-lined, underground burrows
• They use a trapdoor to ambush their prey

The spider detects vibrations from insects walking nearby and quickly leaps out to capture them¹.

Predators

Hourglass Trapdoor Spiders have several predators, including:

• Birds
• Rodents
• Larger arachnids

These predators are usually attracted to the spiders due to their large size and the existence of their burrows².

Comparison table of Prey and Hunting Techniques vs Predators:

Venom & Defense

Venomous or Not?

The Hourglass Trapdoor Spider’s venom is not well documented, but typically, trapdoor spiders are not considered dangerous to humans. Though their bite could cause some discomfort, there is no need for alarm. Some similar non-dangerous spiders include:

• Barn Funnel Weaver Spider
• Jumping Spider

On the other hand, a dangerous venomous spider to be aware of is the Brown Widow Spider¹.

Phragmosis & Severed Abdomen Spider

Phragmosis is a common defense mechanism employed by trapdoor spiders, including the Hourglass Trapdoor Spider². It involves using their body, specifically the rigid disk on their abdomen, to block the entrance of the burrow. This tactic is effective against predators, like wasps and scorpions. Advantages of using phragmosis:

• Prevents predator entry
• Protects eggs and spiderlings in the burrow

One noteworthy phenomenon is the Severed Abdomen Spider, an occurrence where the spider’s abdomen is entirely severed from its body. They can survive this extreme form of self-defense, as their nervous system is not centralized and is distributed throughout their body³.

Conservation & Human Interaction

Importance in Ecosystem

Hourglass trapdoor spiders, like other arachnids, are part of the arthropod family and play a crucial role in their ecosystems. These subterranean hunters help regulate insect populations, serving as natural pest control. Additionally, they provide a food source for larger predators such as birds and reptiles.

Threats & Conservation Efforts

Unfortunately, these spiders face numerous threats, particularly habitat destruction due to human activities. Expansion of urban areas, deforestation, and agricultural practices can lead to the loss of their sandy burrows. Moreover, the presence of invasive species and climate change intensifies their risks.

To protect hourglass trapdoor spiders, it’s essential to emphasize conservation efforts. Some examples include:

• Establishing protected areas for native habitats
• Encouraging responsible land management practices, such as Habitat Conservation Plans

Here’s a quick comparison of the hourglass trapdoor spider with its distant relative, the tarantula:

In summary, hourglass trapdoor spiders demonstrate the interconnected nature of arthropods in their ecosystems. By understanding their importance and addressing the threats they face, we can help conserve these unique creatures and maintain healthy ecological balance.

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 – Folding Door Spider

What kind of spider is this?
Location: Just south of Roseburg, OR
November 28, 2011 10:35 am
I was given an inflatable kayak. When I turned it over, this spider ran out. It was very aggressive, trying to chase me with its front legs lifted. I live in Douglas County, Oregon, and I have NEVER seen a spider like this before. There was no webbing or nest in the kayak. It was a little bigger than a half dollar.
Signature: Heather Goin

Hi Heather,
This appears to us to be a Folding Door Spider, Antrodiaetus pacificus, which we identified on BugGuide.  They are also known as Trapdoor Spiders.  Females rarely leave their burrows, and they tend to have a longer lifespan.  Males tend to leave their burrows at the onset of the autumn rains, and they wander about in search of a mate.  Your individual is a male.  Though his defense posture is threatening, Trapdoor Spiders are not considered a harmful species to humans, though it is possible they might bite.  If that happened, the bite generally causes a brief local reaction.

Wow!  Thanks for your speedy reply!  Glad to know he isn’t harmful! 🙂

Letter 2 – Drowned Trapdoor Spider

Spider found in a pool in Atlanta
Location: Atlanta, GA
April 10, 2011 12:04 pm
Hi Bug Man,
Via facebook, my friend, Marla found this big ”boy.” What kid of spider is it? Seems big and scary. Is it?
Signature: Robin Payne, Snellville, GA

Hi Robin,
This appears to be a male Trapdoor Spider.  Trapdoor Spiders live in burrows with camouflaged, hinged doors.  They ambush unwary prey that happens to walk by.  Trapdoor Spiders are closely related to Tarantulas, though they are much smaller.  Trapdoor Spiders might bite if provoked, but the bite is relatively harmless.  Female Trapdoor Spiders rarely leave their burrows, but male Trapdoor Spiders will wander in search of a mate.  The California Trapdoor Spider frequently falls into swimming pools and the same may be true for other members of the group.  We believe this may be a spider in the genus Myrmekiaphila based on photos posted to BugGuide.  This posting on BugGuide indicates that the species may have a relationship to bodies of water.

Thanks so much.  I sent your note to my friend and we are both glad to know what that big guy is.

Letter 3 – Funnel Weaver Spider from Machu Picchu: Linothele uniformis

Subject:  What kind of spider is this?
Geographic location of the bug:  Peru-Machu Picchu
Date: 08/29/2021
Time: 05:48 PM EDT
Your letter to the bugman:  Hi! I saw the spider pictured in my photo on a rock at Machu Picchu in late August.
How you want your letter signed:  Melinda

Dear Melinda,
This is a primitive spider in the Infraorder Mygalomorphae, a group that includes Tarantulas and Trapdoor Spiders.  Your individual does not look hairy enough to be a Tarantula, so we suspect it is a Trapdoor Spider.  We did try to locate matching images online with no luck, though we searched for both Tarantulas and Trapdoor Spiders in Peru.

Update:  Linothele uniformis
A special thanks to Cesar Crash of Insetologia who wrote in identifying this Mygalomorph as a Funnel Web Spider, Linothele uniformis, and providing this link to Science Press.

Letter 4 – Drowned Trap-Door Spiders

I was cleaning my pool last week and this week and I pulled one of these out each time both were dead. Can you please positively identify them for me. Thank you for your time
Hank Schuchardt
Brooksville,Fl.

Hi Hank,
You have a species of Trap-Door Spider, so called because they build a burrow in sandy soil and create a door. The spiders hide behind the door and jump out with prey, usually small arthropods, pass by. You specimens appear to be males. During mating season, males will sometimes wander in search of a mate. Sadly, they fell into your pool.

Letter 5 – Female California Trapdoor Spider

Subject: Chillin’ California Trap Door Spider Beauty
Location: San Pedro, CA
May 22, 2013 7:09 pm
Look who I found! A big beauty in San Pedro in April, 2013. My friend called me and said she’d found a pipe in her bare-earth backyard. She then called back and said it was a tube. I came by to investigate. We gently opened a few trap doors and this beauty clung to the top of her trap door, so I gently removed her. After a weak threat display, I picked her up, took photos, and gently placed her back, thanking her and closing her trap door.
Signature: Darlene King

Dear Darlene,
Thank you so much for sending us this exciting posting.  Though we have numerous photos of male California Trapdoor Spiders, Bothriocyrtum californicum, photos of females are noticeable absent on our site.  We believe your identification is correct because of the resemblance to this California Trapdoor Spider on BugGuide.  Up until recently, the information page on BugGuide has been quite spare, but this marvelous addition is quite fascinating: “According to Guinness World Records, as of 2009, this is the strongest spider. It has been able to resist a force 38 times its own weight when defending its trapdoor. This equates to a man trying to hold a door closed while it is being pulled on the other side by a small jet plane!(1) Unfortunately, the Guinness book doesn’t mention if it’s the strongest North American spider or if it’s the strongest in the world. Also, one thing to think about is whether or not every spider’s strength has been measured. I guess one can safely say that the information is flawed in that aspect, but it still asserts the fact that these spiders ARE very strong.”Because of habitat loss in urban areas, California Trapdoor Spiders are becoming scarcer in many parts of their range, including Los Angeles, where the preservation of more open space might be a necessity for their survival.  Our own nearly 36 acre natural gem, Elyria Canyon Park, is likely a contributing factor in the presence of California Trapdoor Spiders where males frequently fall into swimming pools at the start of rainy season.  Me must say we are quite impressed with your handling of this large but benign spider.  Trapdoor Spiders wait patiently in their lairs to pounce upon any small arthropod or possibly even small vertebrate that crosses their perimeter. 

We like the use of the dogs for scale.

Letter 6 – First Heavy Rains bring out male California Trapdoor Spider

Subject: Spider
Location: Santa Clarita, CA
December 18, 2014 8:51 am
found this spider climbing up my patio. Wondering what it is
Signature: Thank you

This gorgeous creature is a male California Trapdoor Spider, and we frequently receive sightings and submissions after the first heavy rains of the season when the males leave their burrows and seek mates.

Letter 7 – Folding Door Spider

Secretive nocturnal spider from Vancouver island
Hello, I’ve been waiting for your site to be back up to ask you what this spider is. I love spiders and researching them and am slightly embarrassed I have no idea what this is. I found him running full tilt across a sidewalk from a hedge towards a main road about 2 am in the morning in Victoria, vancouver island BC. He froze and posed for a picture (a couple since I couldn’t fix the macro on my camera) I’d say that he was about the size of a quarter around, he was easy to spot in the dark because he was so big, like bulky. I went through every spider picture on your site, is it a trapdoor spider? I realize I should have got a better picture of the eye arrangement.
Holly
Victoria, British Columbia

Hi Holly,
We believe we have matched your spider to a Folding Door Spider in the genus Antrodiaetus that is posted on BugGuide.

Letter 8 – Folding Door Spider

Identify spider please
Location: South British Columbia, Canada. Okanagan Region.
September 24, 2011 4:18 pm
Hello,
We have these spiders come out in fall. Someone identified them as a type of trap door, related to tarantula. I would like another opinion please. They have ranged from not aggressive at all to being very aggressive. We have warm to hot summers and mild winters. They like to come inside our house when it gets cool out in fall and when maybe it is mating season?
Thank you,
Curt
Signature: Best wishes?

Hi Curt,
We agree with the identification you received, however, we will take that a bit farther.  Based on photos posted to BugGuide, we believe your spider is the same species as an unidentified species in the genus Antrodiaetus.  There are several images on BugGuide from the Pacific Northwest with the same coloration.  Folding Door Spiders are one group of Trapdoor Spiders.  We also believe your individual is a male.  Males often wander in search of mates while females remain in their burrows, hence it is less likely to encounter a female Trapdoor Spider.  Despite your observation that some individuals act aggressively, Trapdoor Spiders are not considered a harmful species to humans.

Hi Daniel,
Awesome, thank you very much for your reply. I appreciate the time you have taken.
This one in particular was very calm. When I find them in our house, I always catch them and let them go outside. It gives us an opportunity to have a good look at them as they’re quite interesting. Over the past ten years or so, we have run into several wandering around our back door and in our basement. In addition, we have a lot that look like different types of wolf spiders but many more that look like the hobo spider too. I find it hard to tell the difference.
Regarding the folding door spider, the first time I saw one was when our cat went to get a closer look at something. I saw the spider rear up and then run after our cat! I thought I was seeing things! It kind of looked like it was bent upward and its front legs were spread apart and in the air as it ran. In another instance, when I was trying to catch one in our house, it reared up like the one that chased after our cat and then jumped at me. I had the heebie jeebies for days. All the other ones we’ve caught have been calm. Maybe the ones that have seemed aggressive have not been, and are just after warmth or going towards vibration or something? Or maybe they were just very passionate? Seems too Hollywood.
Thank you for the information.
Curt

Letter 9 – Folding Door Spider

Subject: Brown spider photo at butt lake northern california
Location: Northern California Butt Lake
July 1, 2015 7:01 pm
Dear bug an a friend took the picture while we were camping just wondering what it is. Thank you.
Signature: Wondering about the bug

We believe this is a Folding Door Spider in the genus Antrodiaetus, and it really looks to us to resemble the female Antrodiaetus gertschi that is pictured on BugGuide by a single sighting in Northern California.  You can try browsing through the genus page on BugGuide to see if some other species more closely resembles your individual.

Letter 10 – Male California Trap-Door Spider

UNKNOWN SPIDER-STH CALIFORNIA.
HI BUGMAN,
This spider was found in a pool in Calabasas Southern California. I have seen 3 other website site images of this spider, all found in pools in Southern California. No one has managed to identify it so far?
Cheers,
Derek.

Hi Derek,
Just last week, our neighbors Jeannie and Ayn delivered a similar spider to our Mt. Washington doorstep. It was found in their pool. You both, and I assume the three other people online as well, have a male California Trap-Door Spider, Bothriocyrtum californicum. The males have the reddish abdomen and longer legs. Females are much stouter spiders with shorter legs. They build burrows with trap-doors and ambush prey that wanders past. They prefer sunny, dry, south-facing hillsides. The males are much shorter lived than the females who rarely leave their burrows. Males have the longer legs so they can travel in search of a mate. Often they meet an untimely end by drowning in swimming pools. Rains seem to trigger the mating activity.