Why do we have horrible, awful, nasty and scary spiders? Food. Spiders would not be harboring or hunting in an environment devoid of food. Their mere presence is really symptomatic of a different pest issue — usually small flies, or what the industry dubs “outside occasional invaders.”
Spiders hunt and harbor in the same general area. Visual inspection with a good flashlight will reveal hotspots of activity. So will looking for areas of congregating dead insects.
When properly placed, glueboard monitors can help detect — and more importantly, identify — the species with which you are dealing. Is it really a brown recluse spider, or just another wolf spider?
Finally, while insecticide use can work for controlling spiders, we find habitat modification, sanitation and eliminating their food source are also important components to success.