Yeah the main problem I have with laying down poison or anything like that is that we have 4 dogs. 2 of them LOVE to chase and eat spiders and other bugs. Thankfully we haven't found a LOT of widows, but I'm absolutely sure they're under the house, and are coming through the cracks at some point. Luckily, it's just been 3 so far.
Use the Diamataceous Earth then Alex. It is safe for your bigger critters, you can actually sprinkle it on the dogs as a natural flea killer/preventative. Most animals can ingest a spider and at the worst just feel pukey.
The most important thing to be learned from those who demand "Equality For All" is that all are not equal...
Gun Control - seeking a Hardware solution for a Software problem...