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Spiders in Southwestern Colorado

Colorado's diverse climate is an ideal location for numerous spider species. Though many people are instinctively afraid of spiders, very few spiders pose a threat to human health. Even venomous spiders play a vital role in the ecosystem by killing common insect pests. Few people will ever be bitten by a spider, and bites by venomous spiders result in death less than 1 percent of the time. Knowing the spiders common in Colorado can make spider identification easier and may help to ameliorate fears about venomous spiders.

Tarantulas
- Tarantulas have a very long life span.
  
  Tarantulas live in the southern parts of Colorado. These large, hairy-legged spiders with thick abdomens are among the most easily recognized spiders in the state. They can live up to 20 years and do not make webs. Though these large arachnids may look intimidating, they are not venomous and are generally not aggressive. When frightened, they can shoot hairs from their abdomen. These hairs may cause a rash or allergic reaction if they come into contact with skin.
Jumping Spiders
- Jumping spiders have very good eyesight.
  
  Jumping spiders are frequently confused with tarantulas because of their large bodies and hairy legs. They have large eyes that are visible from a distance and their abdomens are typically more flattened and rounded than tarantulas' abdomens. Jumping spiders prefer sunny garden locations but occasionally enter human homes. These spiders can jump up to 40 times their own height and do not build webs. They are not venomous to humans and are not aggressive.
Wolf Spiders
- Wolf spiders are one of the most common spiders in the United States, and several species of wolf spider live in Colorado. These spiders hunt their prey by sight and do not build webs. They have elongated brown or gray bodies and may have a stripe down the center of their abdomen. They are small to medium-sized spiders, usually measuring 1/2 to 1 inch long. They are common in human homes, particularly in dark and humid areas. Their bites are very painful and can cause infections and allergic reactions.
Orb Weavers
- Orb weavers build webs in sunny locations.
  
  Orb weavers are most commonly found in sunny locations, where they build large, spiral-shaped webs. They are typically black with bright bands or spots of color, and they measure about 1 inch in length. These spiders are occasionally confused with venomous spiders because of their bright color patterns, but are neither venomous nor aggressive.
Venomous Spiders
- Black widow spiders have red markings on their abdomens.
  
  The two potentially deadly spiders in Colorado are the black widow spider and the brown recluse. Both are found in dark locations with little foot traffic like sheds and woodpiles. The black widow instinctively bites when something comes into contact with its web, but the brown recluse is less aggressive. Recognize black widows by their black or brown bodies with red hourglass shapes on their abdomens. Brown recluses are brown with a tan or beige violin-shaped marking on their abdomens.

Insects & Science