We found a black window in our home last night on the ceiling of the kitchen. We do not have any other pest problems except an occasional non-poisonous spider and the earwigs that are everywhere in October. Should I spray to make sure there are no others and that the widow did not leave eggs? I found a "natural" pest control company that could spray inside and outside the house with a mixture of Rosemary oil, Geraniol, Peppermint oil, Wintergreen, White Mineral oil and Polyglyceryl Oleate. Would this be helpful as a precaution?
Jefferson County Colorado
It doesn't sound like the entire house needs to be treated, given that you've only encountered one individual. At this point I would look around your house for possible infestation sources and treat those if you find any. You can find details in http://extension.colostate.edu/topic-areas/insects/western-widow-spider-5-605/ and http://extension.colostate.edu/topic-areas/insects/spiders-in-the-home-5-512/.