I have no idea, But I am a fan on 1 can of fly spray per spider.. lol and our new house when we moved to Toowoomba was INFECTED with spiders outside and heaps inside, so I went NUTS with the fly spray... and I used the mortein outdoor 6 month spray too. And I hate flies, so I used like half a can chasing flies around the house.

I probably shouldn't have being pregnant and all, but my DD is perfect and fine. I understand your need to kill them!

I am sure they have more natural ones then mortein etc?