Mosquito Steve's spider control treats the perimeter where spiders actually enter, eaves, soffits, porch corners, window and door frames, garage tracks, docks, and the foundation line with plant-based essential oils rather than poison. Spiders sense through their legs, so a treated surface reads as hostile and they move on. One application holds for about 30 days and longer. It's also the only kind of product you can legally use near a body of water, which is why lake houses and boat docks use it.