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Welcome to the Colorado State University Extension Western Colorado Entomology web site. This site was created and is maintained by Tri River Area Extension Entomology & Agronomy, and is dedicated to presenting factual information on the insects and insect related issues affecting western Colorado.

Photo Gallery, Arachnida-Spiders and Scorpions   arrow

Arachnida-Spiders and Scorpions


Araneus gemmoides

Cat faced spider
These cat faced spiders are very visible in the fall. They are in the orb-weaver family.

Colorado Insects of Interest Sheet-Cat-Faced Spiders

Photo by Tami Mattics.




Lactrodectrus mactans

Western Widow Spider
Western widow are common inhabitants of western Colorado.

Colorado State University Fact Sheet-Western Widow Spider
Western Widow Spider

Photo by Tami Mattics


Crab spider
Crab spiders are common in western Colorado. They can be recognized by their long front 2 pair of legs. Crab Spider

Paruroctonus boreus

Northern scorpion
The northern scorpion is common in desert areas across western Colorado. This one was photographed on East Orchard Mesa near Grand Junction. Northern Scorpion

Dysdera crocata

Wood Louse Hunter
“Roly-poly Hunter”
This smooth bodied spider is perhaps best distinguished by its large fangs which it uses to feed on pillbugs (roly-polies) and other hard-bodied prey. When full grown they are about .5 inch in length. Dysdera have a generally creamy gray body with distinctly reddish legs and cephalothorax. They live in a silk retreat and hunt at night. Their bite can be painful but they are not aggressive and their venom is not known to cause medical problems.

Colorado Insects of Interest Fact Sheet-Roly-Poly Killer
Roly-poly killer