I've found that Ortho Home Defense MAX works splendidly and you need to apply it only about twice a year. It even works on my northern property, which is quite near Lake Huron, so naturally, we have far too many spiders. Only problem with it is that it supposedly doesn't work for Black Widow and Brown Recluse spiders, go figure. Absolutely the two you want to always kill. At any rate, it has cut down on the spider population at both my houses, immensely. I buy it by the jug. I also suggest Riddex plug-ins, as they also work at cutting down the numbers. Both products together form a great 1-2 punch.