.jpg){kind=link}
Mediterranean recluse
Loxosceles rufescens
- Venom
- No official source we use states whether this animal is venomous. That does not mean it is harmless: do not handle it.
Are there brown recluse spiders in Colorado?
Last checked November 3, 2026 against official sources.
Rarely.
CSU Extension says brown recluse and all other recluse spiders are extremely rare in Colorado; sightings often come from spiders carried in from other states.
Colorado State University Extension: “The brown recluse, and all other recluse spiders, are extremely rare in Colorado.” Source
More official answers for Colorado
Are there black widows in Colorado?
Yes. CSU Extension says widow spiders, particularly the western widow, are common in Colorado. Colorado State University Extension
Are there tarantulas in Colorado?
Yes. CSU Extension says tarantulas are found in southeastern and southwestern Colorado. Colorado State University Extension
On Colorado's official list
All spiders in the state: Colorado spiders.
Where the brown recluse spider lives in the US
- Native or listed
- Nonnative or not established
- No official record in our data
- 1–9
- 10–99
- 100–999
- 1,000+
What else it could be
Wolf spiders
UC IPM lists wolf spiders among the brown spiders often mistaken for recluses. They have 8 eyes, so they can be ruled out quickly.
Photo: Sam Taylor · CC BY 4.0 · iNaturalist Southern house spider (male)
UF/IFAS says males are often mistaken for brown recluses. The brown recluse has six eyes in three separate pairs, while the southern house spider has eight eyes bunched together at the front.
Photo: kcthetc1 · CC0 1.0 · iNaturalist Huntsman spider
UF/IFAS says its carapace pattern is reversed: a light central mark on a dark background. Adults are also much larger than a brown recluse.
Photo: Meghan Cassidy · CC BY-SA 4.0 · iNaturalist · resized Woodlouse spider
Ohio DNR says it is sometimes confused with the recluse, perhaps because it also has six eyes; recluses are much smaller, dull brown and have tiny fangs. UC IPM says the woodlouse spider's six eyes are in two groups of three (a recluse has three pairs) and it has no body markings.
-
Photo: jacilluch · CC BY-SA 2.0 · Wikimedia Commons · resized Mediterranean recluse
Alabama Extension says the Mediterranean and Chilean recluses closely resemble the brown recluse and are difficult to tell apart from it; it has the same six eyes in three pairs. UC IPM says telling recluse species apart needs a high-magnification microscope and a spider expert. It is not native; Alabama Extension says it has been found in only a few small, isolated locations, and Ohio DNR reports it from buildings in several Ohio cities.
When spiders are seen in Colorado
If you see one in Colorado
Keep your distance and do not try to catch or handle it. Invasive species: file a report with CPW (online "Report a Sighting" form linked from cpw.state.co.us/invasive-wildlife). Injured/abandoned animals, feeding or illegal activity: CPW Denver Headquarters 303-297-1192 or any CPW office; anonymous: Operation Game Thief 877-265-6648. After-hours emergency: Colorado State Patrol 303-239-4500. Wildlife posing immediate danger: local CPW office or law enforcement. Colorado Parks and Wildlife
Other questions about Colorado
Sources
- Brown Recluse Spiders in Colorado: Recognition and Spiders of Similar Appearance. Colorado State University Extension. Published February 2008; checked November 3, 2026.
Quoted passages (1)
“The brown recluse, and all other recluse spiders, are extremely rare in Colorado.”
- Spiders in the Home (Fact Sheet 5.512). Colorado State University Extension. Published September 2013; checked November 3, 2026.
Quoted passages (2)
“Widow spiders, particularly the western widow (Latrodectus hesperus), are common in Colorado.”
“Tarantulas are found in southeastern and southwestern Colorado.”
- Known Invasive Wildlife in Colorado. Colorado Parks and Wildlife. page states 2026-01-21T15:12:28-0700; checked November 3, 2026.
Quoted passages (1)
“If you spot any invasive species, file a report with CPW.”
- GBIF.org occurrence records, human observations licensed CC0 1.0 or CC BY 4.0 only, accessed November 3, 2026. The datasets behind these counts are listed on our Sources page.