Brown Recluse spiders in Colorado

Asked August 4, 2015, 2:42 PM EDT

HI There,

I've read through your informative pages on brown recluse spiders in Colorado and understand it's very unlikely for them to take up residence here. However, I note the date on your material is 2012 and I'm just curious whether anybody has noted possible increased activity following the flood of 2013 and unusually wet weather patterns we've had over the last several years in some areas along the foothills of the Front Range? I live in Eldorado Canyon/Eldorado Springs (south Boulder County). Our dark, damp crawl space under the house has really yet to dry out and there is some impressive spider activity in the farthest remote corner of that space. Our experienced furnace repair guy feels they were brown recluses--he saw several. This is an area that gets zero light or human activity (except when the furnace guy is there). Could these in fact be brown recluses?

Boulder County Colorado

1 Response

I recently heard a talk by Paula Cushing of the Denver Museum of Nature and Science and the expert on Colorado spiders. Her opinion is that brown recluse spiders may be introduced on moving boxes but are not likely to survive.
I recommend that you place some sticky traps (cardboard with glue, usually shaped like a tent) and see what you catch. You can send traps for identification to the diagnostic lab here on the CSU campus. Mail to:
PLANT/INSECT ID & DIAGNOSTIC CLINIC
E-215 PLANT SCIENCES BUILDING
COLORADO STATE UNIVERSITY
FORT COLLINS, CO 80523-1177
(970) 491-6950