Trapdoor Spiders: Burrows, Bites and Where They Live
A trapdoor spider is a stout, burrowing relative of tarantulas that lives in a silk-lined tunnel sealed with a hinged lid of silk and soil, and ambushes insects that walk past the door. In the US the common ones are the cork-lid trapdoor spiders (Ummidia) of the East, South and Southwest, and the California trapdoor spider. They can bite if handled and the bite is painful, but extension entomologists do not regard it as medically serious. Females stay in their burrows for years; the ones people find are mostly wandering males.
Most people never see a trapdoor spider, because the lid is camouflaged with soil and leaf litter. They notice one when a male leaves his burrow to look for a mate, or when a raking or digging job flips open a door. This guide covers the US species, how to tell a trapdoor burrow from a tarantula or wolf spider hole, when males wander, and what to do about one.
Is it a trapdoor spider, a tarantula or a wolf spider?
All three dig or use holes in the ground, and all three get called tarantulas. The burrow entrance is the quickest way to tell them apart.
| Trapdoor spider | Tarantula | Wolf spider | |
|---|---|---|---|
| Burrow entrance | Hinged lid of silk and soil, closed most of the time; about 3/4 to 1 inch across | Open hole with a silk collar, veiled with silk by day; plugged shut in winter | Open hole or tunnel, sometimes under boards or stones; no lid |
| Burrow depth | Usually under 5 in (Ummidia, Arkansas); up to 8 in (California trapdoor) | Can extend more than a foot | Holes or tunnels in soil, often under boards, stones or firewood |
| Body | Stout, glossy, short thick legs; females much larger than males | Large and hairy, 1 to 2 in body | Hairy, patterned, long legs; 16 to 35 mm in large species |
| Fangs | Point downward and strike in a stabbing motion | Move in a vertical plane | Move sideways, like most spiders |
| Hunting | Waits under the lid, lunges at prey that touches or nears it | Sits at the burrow edge at night, rushes prey within 2 to 3 in | Hunts in the open, day and night; eyes shine green in a torch beam |
| When seen in the open | Wandering males: early summer (Ummidia), autumn and winter rains (California) | Wandering males, late summer and early autumn | All year; peaks in October |
Compiled by The Pest Control Brief from the University of Arkansas Arthropod Museum, UC Irvine (P. J. Bryant), Mississippi State University Extension, Colorado State University, Penn State Extension and UC IPM Pest Notes 7442.
If you find a lid, it is a trapdoor spider. If you find a hole with a silky rim and no lid in the Southwest or Great Plains, it is more likely a tarantula. A large hairy spider running across a patio at night is most often a wolf spider; see our wolf spider guide, and our spider identification guide for the spiders that matter medically.
The US trapdoor spiders
“Trapdoor spider” is a lifestyle, not one species. It covers several families of mygalomorph spiders, the same suborder as tarantulas. Mississippi State’s extension entomologist Blake Layton calls them “the closest thing we have to tarantulas” in that state.
| Group | Where | Door and burrow | Key features |
|---|---|---|---|
| Cork-lid trapdoor spiders, Ummidia | US species range north to Maryland and Ohio, south to Florida and west to Arizona | Thick, bevelled cork-type lid that fits snugly; burrow often in slopes and ravine sides, under leaf litter | Glossy, dark, stout; U. audouini is Mississippi’s largest; 33 new New World species described in 2021 |
| California trapdoor spider, Bothriocyrtum californicum | California and the south-western US | D-shaped hinged lid fitting tightly; vertical tube up to about 3/4 in wide and 8 in deep | Females short, thick legs and brown abdomen; males longer, thinner legs and a redder abdomen |
| Truncated trapdoor spiders, Cyclocosmia | Two US species, C. truncata and C. torreya | Abdomen ends in a hard, ribbed disc that plugs the burrow | When threatened it dives head first and the disc forms a false door |
| Other California trapdoor spiders, Euctenizidae | California, including coastal dunes | Burrows with doors | Includes Aptostichus simus, a coastal dune endemic |
Compiled by The Pest Control Brief from Godwin and Bond, ZooKeys 1027 (2021); Bond and Coyle, Journal of Arachnology 23 (1995); Mississippi State University Extension; UC Irvine; San Diego Natural History Museum; Xu et al., ZooKeys (2017); Jochim et al., Ecology and Evolution (2025).
The genus Ummidia is still being sorted out. When Rebecca Godwin and Jason Bond began their 2021 revision, ten nominal Ummidia species were recorded from the United States, with descriptions too vague to separate them, and earlier workers estimated as many as 50 undescribed North American species. Their revision described 33 new species across the Americas. For a homeowner, “Ummidia trapdoor spider” is as precise as identification usually gets.
How big are trapdoor spiders?
Females are chunky rather than leggy. Mississippi State describes Ummidia as possibly the state’s heaviest spiders even though their leg span is modest, and measured one large female U. audouini at 1.5 inches (about 38 mm). Males are much smaller and slimmer. Published measurements are mostly of single specimens, so treat the chart below as a guide to scale rather than a species range.
Where do trapdoor spiders live?
Ummidia burrows are cryptic, patchy in distribution and “very difficult to find,” according to the 2021 revision, and are often covered in leaf litter. The University of Arkansas Arthropod Museum says burrows there are often found on the sides of forested ravines. Bond and Coyle found a Central American species preferred steep slopes and open, early-stage habitat, consistent with spiderlings dispersing by ballooning on silk threads, a habit seen in some Ummidia species but not in most mygalomorphs.
Our analysis of iNaturalist research-grade records shows where Ummidia is photographed most relative to everything else people record. North Carolina leads with 365 records (1.27 per 10,000 observations), followed by Oklahoma, Arkansas, South Carolina, Tennessee and Georgia. Texas has many records (273) but a low rate, because so much else is photographed there. There are 1,612 US Ummidia records in all, and because burrows are hidden, these mostly reflect wandering males crossing paths and patios rather than where burrows are densest.
When males wander
Female trapdoor spiders rarely leave the burrow. Mississippi State notes that males “do not live in burrows as adults” and are “sometimes spotted wandering about over open ground in search of females,” which is why males are seen more often than females. The timing differs sharply between the eastern and Californian species.
Ummidia records are concentrated in a short summer burst: 530 in June and 586 in July, together 69 per cent of the year’s 1,617 records, with the seasonality index jumping from 78 in May to 365 in July and falling to 39 in August. The Arkansas Arthropod Museum puts male wandering in July and August, so the exact weeks vary by species and place. The California trapdoor spider is the mirror image: its records peak from November to January (index 284 in November, 225 in January), which fits UC Irvine’s note that males wander in the autumn, and the rainy season when UC IPM says burrow-living spiders may leave flooded burrows. Wolf spiders, for comparison, peak in October.
Burrows and the door
The Arkansas Arthropod Museum describes Ummidia doors as about one inch in diameter, made of silk camouflaged with soil and plant debris and hinged on one side, over burrows usually less than five inches deep. In Costa Rica, Bond and Coyle found the door thick and rigid with bevelled edges that fit a matching bevel in the entrance rim, like a cork. Spiders pulled their doors shut and held them tightly closed when lit by a torch, and even resisted a knife blade by day.
Tarantula burrows are the deep ones. Colorado State says they can extend more than a foot, with a silk collar at the entrance and a silk veil over it by day. Late in the season the tarantula plugs the entrance solid and stays sealed in through the cold months. A lid that swings on a hinge is unique to trapdoor spiders.
What they eat and what eats them
Trapdoor spiders are sit-and-wait predators of insects and other small arthropods. At night an Ummidia holds the door ajar and waits beneath it. In Bond and Coyle’s observations the spider kept the door open 1 to 3 mm, with its front legs resting on the rim, and struck when prey touched the lid or came within about 1 to 5 mm: a harvestman, a caterpillar and a small true bug. The door popped open, the spider lunged out while anchoring itself with its hind legs, and pulled the prey in. Some web pages list frogs, birds and mice as prey; we found no extension or research source supporting that for US species.
The main enemies are spider wasps (family Pompilidae). Mississippi State describes a reader watching a wasp paralyse a female trapdoor spider and drag it into a silk-lined hole; spider wasps then lay their eggs in the paralysed spider. The best-known spider wasps are the tarantula hawks covered in our tarantula hawk guide. UC Irvine adds that small mammals dig up burrows and eat the spiders.
How long do trapdoor spiders live?
Females live for many years in the same burrow, enlarging it as they grow. Mississippi State cites an Australian trapdoor spider documented to live 43 years, a female followed in a long-term field study in Western Australia (Mason and colleagues, Pacific Conservation Biology, 2018). Males are relatively short-lived once mature. Our guide to how long spiders live compares lifespans across species.
The California trapdoor spider also shows maternal care: UC Irvine reports the female lays several hundred eggs and feeds the spiderlings over their first winter before they leave to dig their own burrows.
Bites and venom
Trapdoor spiders have large fangs that point downward, and they bite when handled or dug out. The Arkansas Arthropod Museum says they “appear quite pugnacious and readily bite” when first disturbed, “but they soon calm down.” In the 1920s the University of Arkansas entomologist W. J. Baerg let one hold its fangs in his finger for about a minute and a half and reported “no appreciable effects other than the puncture wounds.” Mississippi State’s verdict is that the bite, “though painful,” is “not considered seriously venomous to humans.” Anyone with a reaction beyond local pain, or any bite that worsens, should see a doctor.
What to do about trapdoor spiders
In almost every case, nothing. A burrow in the garden is a sign of undisturbed soil and a predator of ground insects, and the spider is very unlikely to settle indoors: females almost never leave the burrow. None of the extension sources we read recommends treating trapdoor spiders.
- A burrow in the yard: leave it. If it is somewhere you dig, wear gloves, as you would for any burrowing animal.
- A male indoors or on the patio: it is a wanderer looking for a female and will not set up home. UC IPM’s method for removing a spider works: place a jar over it, slide a card underneath and release it outdoors.
- Several turning up inside: seal gaps under doors and around utility lines and clear debris from the foundation. See bugs in the house after rain and our guide to getting rid of spiders in the house.
- Pesticides: not warranted for a spider that lives outdoors in a sealed burrow. Perimeter sprays are unlikely to reach it.
Frequently asked questions
Are trapdoor spiders poisonous?
They are venomous, as almost all spiders are, but not considered dangerous. Mississippi State University Extension describes the bite as painful but “not considered seriously venomous to humans,” and a University of Arkansas entomologist who let one bite him reported no effects beyond the puncture wounds. They are not poisonous to touch. Anyone who has an unusual reaction should see a doctor.
What is a trapdoor spider?
A burrowing spider related to tarantulas that lives in a silk-lined tunnel closed by a hinged lid of silk, soil and plant debris. It waits under the lid and lunges at insects that walk past. In the US the main groups are the cork-lid trapdoor spiders (Ummidia), the California trapdoor spider and two Cyclocosmia species with a disc-shaped abdomen.
How to get rid of trapdoor spiders?
Usually you do not need to. They live outdoors in burrows, eat ground insects and are very unlikely to settle in a house. A wandering male indoors can be caught under a jar and released outside. If several get in, seal gaps under doors and around pipes. Perimeter sprays are unlikely to reach a spider sealed in its burrow, and no extension source we read recommends treating them.
Do trapdoor spiders bite?
Yes, if handled or dug out. The University of Arkansas Arthropod Museum says they bite readily when first disturbed but soon calm down. The bite is painful because the fangs are large and strike downward, but extension entomologists do not regard it as medically serious. Bites happen almost only when someone picks one up or disturbs a burrow with bare hands.
What do trapdoor spiders eat?
Insects and other small arthropods that walk close to the burrow. In field observations of Ummidia, the spider waited with the door open a few millimetres and struck at prey that touched the lid or came within about 5 mm, including a harvestman, a caterpillar and a small true bug. Claims that US species eat frogs, birds or mice are not supported by the sources we read.
Sources
- University of Arkansas Arthropod Museum. Trapdoor spider (Ummidia).
- Mississippi State University Extension. Bug’s Eye View: Trapdoor Spider, Vol. 7 No. 28 (B. Layton), 2021.
- Godwin R. L., Bond J. E. Taxonomic revisions in the North American and Caribbean trapdoor spider genus Ummidia. ZooKeys 1027: 1 to 165, 2021.
- Bond J. E., Coyle F. A. Observations on the natural history of an Ummidia trapdoor spider from Costa Rica. Journal of Arachnology 23: 157 to 164, 1995.
- UC Irvine, Arthropods of Orange County (P. J. Bryant). California Trapdoor Spider, Bothriocyrtum californicum.
- Xu X. et al. Trapdoor spiders of the genus Cyclocosmia from China and Vietnam. ZooKeys, 2017.
- Colorado State University. Colorado Arachnids of Interest: Colorado Tarantulas.
- UC Statewide IPM Program. Pest Notes: Spiders, Publication 7442; Pest Notes: Brown Recluse and Other Recluse Spiders, Publication 7468.
- San Diego Natural History Museum. Coast to Cactus: Trapdoor Spider.
- Jochim E. E., Starrett J., Briggs H. R., Bond J. E. Speciation pattern and process in the California coastal dune endemic trapdoor spider Aptostichus simus. Ecology and Evolution, 2025.
- Penn State Extension. Wolf Spiders.
- Texas A&M AgriLife Extension, Urban Programs El Paso. Ummidia cork-lid trapdoor spider record, 2023.
- LSU AgCenter. Loxosceles spp., Brown Recluse and Mediterranean Recluse Spiders.
- Mason L. D. and colleagues. Pacific Conservation Biology, 2018 (43-year Gaius villosus record, as cited by Mississippi State University Extension).
- The Pest Control Brief analysis of iNaturalist research-grade records, pulled October 2026.
