What kind of spiders and how to rid of them!

Asked October 23, 2018, 11:21 PM EDT

Just moved into townhouse in Northern Colorado. Upon initial inspection of home (prior to move-in), no spider problem was evident. It's now fall (Sept-Oct), and I have 2-4 spiders on the walls of unfinished basement daily (image attached). Did some research; looks like they might either be Funnel Weaver spiders (bite?), or worse, a group of Brown Recluses (family member bitten Brown Recluse at her own home once, and it took a very look time to recover from that large, painful bite). Whatever these are, how should I get rid of them?? Have had cancer before, so don't like to use strong pesticides if I can help it. THANK YOU.

Larimer County Colorado

4 Responses

Funnel weaver spiders are quite common here. See https://webdoc.agsci.colostate.edu/bspm/Arachnida%20(Arachnids)/Funnel%20Weaver%20Spiders.pdf for details. Brown recluse spiders, fortunately, are not found here, as discussed in http://extension.colostate.edu/topic-areas/insects/brown-recluse-spiders-in-colorado-recognition-and... . http://extension.colostate.edu/topic-areas/insects/spiders-in-the-home-5-512/ discusses various Colorado spiders and gives suggestions for their management.

Thank you Frank, but not exactly an answer to my question--was aware of that same generic info I found on your website...Question was what kind of spiders do I likely have based on my image (now re-attached), and HOW should I get rid of them. A friend suggested plug in sonic devices--your thoughts on all the above?

It's very difficult to provide a specific spider id from a photo, but this one does look like a female barn funnel weaver, which is, as you suspected, one of the funnel weavers.

Spider problems tend to be seasonal with the peak being this time of year when they are seeking shelter for the winter. Preventive measures include keeping potential hiding places (vegetation, firewood, etc) away from the townhouse. I'm not sure who manages your grounds, but a residual insecticide treatment to the outside of the structure (ground and near-ground parts of the structure's exterior). I realize that you want to avoid pesticide use, but this might help and avoid the need for interior treatments. Finally, sealing up as many possible entrances is also important (and something I need to do to my basement windows this weekend).

Indoors, eliminating potential hiding places and frequent removal of webbing and spiders (if it doesn't bother you to do so) are important. I would wait and see how the preventive measures outside work before considering any indoor pesticide use.

There is absolutely no scientific evidence that any of the ultrasonic devices are effective against spiders. I don't recommend them.

Thank you so much, Frank! Your information is very helpful.