Venomous spiders in Colorado

Venomous spiders living in Colorado

2species, plus 1 with rare records

Black widow, Tarantula.

How to recognize them

Black widow Latrodectus mactans, L. variolus, L. hesperus

Shiny black female with a round abdomen
Red hourglass or two red marks under the abdomen
Messy, strong web low to the ground, often in garages, wood piles and water meters

Tarantula Aphonopelma spp.

Large, hairy, brown to black spider
Lives in a burrow with silk around the entrance
Males wander in late summer and fall looking for mates

Almost all spiders have venom, but very few can hurt people. We list the ones with medically significant bites plus a few that people often worry about.

Counties with records

None recorded
1 species
2
3 to 4
5 or more

Venomous spiders with open GBIF records, by county: 27 counties so far. Blank does not mean absent.

Active months

Open records of venomous spiders in Colorado by month; most fall in August to October.

Rare records

Rare records Brown widow 1 open record

Harmless spiders people mistake for them

Quick answers

Questions

How many venomous spiders are in Colorado?

2 species live in the state: Black widow and Tarantula.

Which venomous spiders in Colorado are dangerous?

Black widow: bites or stings need medical care.

When are venomous spiders most active in Colorado?

Most open records fall in August to October.