A Guide to the Amphibians
and Reptiles of California

Western Threadsnake - Rena humilis

Desert Threadsnake - Rena humilis cahuilae

Klauber, 1931

(= Desert Blind Snake - Leptotyphlops humilis cahuilae)

Click on a picture for a larger view
Threadsnakes California Range Map
Orange: Range of this subspecies in California
Rena humilis cahuilae - Desert Threadsnake

Range of other subspecies in California:

Red: Rena humilis humilis - Southwestern Threadsnake

Click on the map for a topographical view

Map with California County Names

observation link

Desert Threadsnake
Juvenile, Imperial County
Desert Threadsnake Desert Threadsnake Desert Threadsnake
Adult, Imperial County Adult, San Diego County Desert
Desert Threadsnake Desert Threadsnake Desert Threadsnake
  Adult, San Diego County Desert  
Desert Threadsnake Desert Threadsnake Desert Threadsnake
Juvenile, Imperial County Adult, Imperial County
Desert Threadsnake Desert Threadsnake  
Adult, San Diego County desert. © Gary Nafis. Specimen courtesy of Tim Burkhardt  
Desert Threadsnake Habitat Desert Threadsnake Habitat Desert Threadsnake Habitat
Habitat, Imperial County Habitat, San Diego County Habitat, Imperial County desert
  Desert Threadsnake Habitat  
  Habitat, Imperial County  
Short Videos
Desert Threadsnake Desert Threadsnake  
A large Desert Threadsnake found crossing a road at night was captured then released, wriggling rapidly across the rocky desert ground until it finds a hiding place. This shows how fast a threadsnake is capable of moving when frightened, but not necessarily its typical behavior. This large Desert Threadsnake was observed apparently searching fors then attacking an ant colony that was moving or relocating their eggs in San Diego County. At the end it looks like the snake may have disappeared down into the ant nest. © Jeff Nordland  

Not Dangerous - This snake does not have venom that can cause death or serious illness or injury in most humans.

Commonly described as "harmless" or "not poisonous" to indicate that its bite is not dangerous, but "not venomous" is more accurate. (A poisonous snake can hurt you if you eat it. A venomous snake can hurt you if it bites you.)

Adults 7 - 16 inches long (18-41 cm). Hatchlings are around 4 - 5 inches long (10 - 12.7 cm).

A very thin snake with a blunt head and tail.
The tail is tipped with a small spine.
Eyes are nonfunctional dark spots visible under translucent plates.
The scales are shiny and cycloid.
Belly plates are not enlarged.
The lower jaw is countersunk.
This snake can be mistaken for a large worm.
Color and Pattern
Coloring is brown, purple, or pink.

Similar Snakes in California
There are two subspecies of Western Treadsnake in California. There is also a very similar non-native blindsnake that has been introduced into Southern California and is gradually increasing its range in the state - the Brahminy Blindsnake.

Go to this page to see more information about comparing the Western Threadsnake with the Brahminy Blindsnake, and suggestions about what to do if you think you have found a Brahminy Blindsnake in California.

LIfe History and Behavior

Nocturnal. Occasionally found crawling exposed on surface at night. Sometimes seen crawling on paved roads at night. Hides in cracks and under surface debris in daytime. Sometimes found under rocks, boards, or other surface debris where the soil is slightly moist.
When threatened, this snake often writhes around, forming a tight coil while releasing pungent fluids from the cloaca. These fluids serve to repel defensive attacks by the ants and termites on which it feeds. May also play dead.
Diet and Feeding
Eats ants and termites and their larvae and pupae, and occasionally other small insects.
When hunting for food, burrows under roots, rocks, and into ants nests.
Slender body allows them to forage in their ant and termite prey's burrow systems.
Mates in the spring.
Females are oviparous - laying eggs sometime between July - August, and tending to them.
They may use communal nests.

Inhabits areas where the soil is suitable for burrowing: brushy mountain slopes, deserts, rocky hillsides, washes near streams.

Geographical Range
This subspecies, Rena humilis cahuilae - Desert Threadsnake, is found in southeastern California east of the peninsular ranges into southwest Arizona, south into Sonora and Baja California.

Finding information about the ranges of the subspecies of Rena humilis is difficult, because they are not recognized by many herpetologists. Some field guides show no subspecies. Some show the range of R. h. humilis extending as far north of Needles, while others show it ranging to just north of the Riverside County border at the Colorado River, as I have decided to show on my map, although I am not certain that it is accurate.There is almost no information about the other subspecies found in Mexico so I have not tried to show them on my map.

The species Rena humilis - Western Threadsnake, is found from Southern California east through southern Arizona and New Mexico, into southwestern Texas, and south into Mexico and Baja California, Mexico.

Full Species Range Map
(Several subspecies are sometimes recognized, but I don't know their exact ranges outside of California.)

Notes on Taxonomy
Some herpetologists do not recognize subspecies of Rena humilis. Those who do recognize four subspecies in the United States, and five in Mexico.

In 2009, Adalsteinsson, Branch, Trape, Vitt & Hedges (Molecular Phylogeny, Classification, and Biogeograpy of Snakes of the Family Leptotyphlopidae (Reptilia, Squamata). Zootaxa. 2240: pp. 1 - 50) placed this species in the genus Rena, making it Rena cahuilae.

Alternate and Previous Names (Synonyms)

Rena humilis cahuilae - Desert Threadsnake
Leptotyphlps humilis - Western Blind Snake (Stebbins 1966, 1985, 2003, Stebbins & Mcginnis 2012)
Leptotyphlps humilis cahuilae - Western Worm Snake (Stebbins 1954)
Leptotyphlops humilis - Worm Snake (Ophisaurus ventralis; Glauconia humilis; Stenostoma humile; Siagonodon humilis. California Rena, California Blind Snake; Glass Snake; Sheep-nosed Snake) (Grinnell and Camp 1917)
Leptotyphlops humilis cahuilae - Western worm snake (Klauber 1928)
Worm snake (Stejneger 1891)
Humble sheep snake (Cronise 1868)

Blind snake
Brown blind snake
California worm snake
Cedros island worm snake

Conservation Issues  (Conservation Status)
Family Leptotyphlopidae Threadsnakes (Blind Snakes) Stejneger, 1892
Genus Rena Threadsnakes Baird & Girard, 1853
Species humilis Western Threadsnake Baird & Girard, 1853

cahuilae Desert Threadsnake Klauber, 1931
Original Description
Leptotyphlops - Stejneger, 1892
Leptotyphlops humilis - (Baird & Girard, 1853) - Cat. N. Amer. Rept., Pt. 1, p. 143
Leptotyphlops humilis cahuilae - Klauber, 1931 - Trans. San Diego Soc. Nat. Hist., Vol. 6, No. 23, p. 339

from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz

Meaning of the Scientific Name
Rena = either Latin - Reborn, or Greek - Peace

- Latin - small or ground dwelling -- no specific reason in original description.
cahuilae - of Lake Cahuila -- near the type locality, CA

from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz

Related or Similar California Snakes
R. h. humilis - Southwestern Threadsnake

More Information and References
California Department of Fish and Wildlife

Stebbins, Robert C., and McGinnis, Samuel M.  Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012.

Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972.

Flaxington, William C. Amphibians and Reptiles of California: Field Observations, Distribution, and Natural History. Fieldnotes Press, Anaheim, California, 2021.

Samuel M. McGinnis and Robert C. Stebbins. Peterson Field Guide to Western Reptiles & Amphibians. 4th Edition. Houghton Mifflin Harcourt Publishing Company, 2018.

Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.

Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.

Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998.

Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Snakes of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009.

Bartlett, R. D. & Alan Tennant. Snakes of North America - Western Region. Gulf Publishing Co., 2000.

Brown, Philip R. A Field Guide to Snakes of California. Gulf Publishing Co., 1997.

Ernst, Carl H., Evelyn M. Ernst, & Robert M. Corker. Snakes of the United States and Canada. Smithsonian Institution Press, 2003.

Wright, Albert Hazen & Anna Allen Wright. Handbook of Snakes of the United States and Canada. Cornell University Press, 1957.

Joseph Grinnell and Charles Lewis Camp. A Distributional List of the Amphibians and Reptiles of California. University of California Publications in Zoology Vol. 17, No. 10, pp. 127-208. July 11, 1917.

Conservation Status

The following conservation status listings for this animal are taken from the January 2024 State of California Special Animals List and the January 2024 Federally Listed Endangered and Threatened Animals of California list (unless indicated otherwise below.) Both lists are produced by multiple agencies every year, and sometimes more than once per year, so the conservation status listing information found below might not be from the most recent lists. To make sure you are seeing the most recent listings, go to this California Department of Fish and Wildlife web page where you can search for and download both lists:

A detailed explanation of the meaning of the status listing symbols can be found at the beginning of the two lists. For quick reference, I have included them on my Special Status Information page.

If no status is listed here, the animal is not included on either list. This most likely indicates that there are no serious conservation concerns for the animal. To find out more about an animal's status you can also go to the NatureServe and IUCN websites to check their rankings.

This snake is not included on the Special Animals List, which indicates that there are no significant conservation concerns for it in California.
Organization Status Listing  Notes
NatureServe Global Ranking
NatureServe State Ranking
U.S. Endangered Species Act (ESA) None
California Endangered Species Act (CESA) None
California Department of Fish and Wildlife None
Bureau of Land Management None
USDA Forest Service None


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