That's pretty much what I've heard as well. I had professionals spray for months at an old townhome that was infested with the brown recluse, and it never made a dent in their population from what I could tell.Originally posted by: arcas
While on this topic...
Do any long-lasting sprays work on spiders? I have some Ortho "Home Defense" indoor/outdoor spray and I like it pretty well. Spray it along the garage walls and it kills any ants, centipedes, etc for a good 6-7 months. But it apparently doesn't work like that on spiders. The instructions say that to kill spiders, you have to spray them directly. This works but it kind of defeats the purpose. Do most sprays have this limitation?
I've heard that the spray works on the insects as you mentioned, and as a result the spiders essentially run out of prey items. They then either die or move to another location.
I can't confirm any of this, but like I said, it's what I've heard.